Living Facades

162
living façades A study on the sustainable features of vegetated façade cladding By Roel Rutgers Faculty of Architecture Delft University of Technology Mentors: S. Broersma A.C. van der Linden F.R. Schnater

description

Masterthesis about the sustainable benefits of plants on a facade

Transcript of Living Facades

Page 1: Living Facades

living façades A study on the sustainable features of vegetated façade cladding

By Roel Rutgers

Faculty of Architecture

Delft University of Technology

Mentors:

S. Broersma

A.C. van der Linden

F.R. Schnater

Page 2: Living Facades
Page 3: Living Facades

1

living façades A study on the sustainable features of vegetated façade cladding

By Roel Rutgers

Faculty of Architecture

Delft University of Technology

Mentors:

S. Broersma

A.C. van der Linden

F.R. Schnater

Page 4: Living Facades

2

Page 5: Living Facades

3

summaryThis research focuses on the answer to the question: “What is the absolute contribution of façade planting around the glass of a glass façade compared to a regular glass façade?” From a preceding study on plants, possible sub-questions on the sustainable aspects are formulated. The vegetated cladding will be called a living façade in this report.

The report answers this question by giving requirements to a preceding design project that makes use of a living façade system. The practical and quantitative data that are useful for this design will be collected. The project is placed in Manhattan, which has about the same climate as The Netherlands, just somewhat more extreme.

There are about 350.000 different species of plants. Plants have an influence on the air composition, human sight, water, sound, soil composition, warmth, food production and biodiversity. All will be discussed in this report.

Five different systems to make living façades can be distinguished. The first is the modular green façade, which is a container filled with soil in which the plants grow. The second is the industrial felts system that makes use of an artificial growing medium. Other media than felts can also be used, such as coconut fiber mats. In this system, the plants are constantly irrigated with water and nutrients to prevent the roots from dehydrating. The next system is the façade greening system, which makes the plants grow over the façade instead of on the façade. The system consists of growing containers placed on the ground or hung on the façade and a trellis system that helps the climber plants grow over the façade. The vegetative tiles or stony surfaces are the last system. Most systems in this category are overgrown with mosses. These systems are quite delicate and need a lot of moisture and not too much sunshine. Of all these systems, the façade greening system offers most advantages, because it is light, easy to make and does not need a lot of water. It is pretty artificial though, and does not provide room for other plants than climber plants on the building. The industrial felts or the modular green system would be a better choice if the building should really offer place for nature and more plants should get the possibility of growing on the building.

The aspect ‘food’ is the first of sustainable aspect to be discussed in the report. The urge for alternative ways of food processing exists, because of large population growth. However, living façades are too inefficient and delicate to form the answer to this problem. Urban Farming towers had better be used instead.

One of the biggest impacts of plants on the environment is bio-filtration, which in a broader sense is called phytoremediation. In this process, the microorganisms living between the roots of the plant eat or break down contaminants, which become food for the plant. Plants can also absorb or capture toxic substances and in this way remove them from the environment. Plants can be used for grey water treatment. The design would need 6.000m2 to treat all grey water of its users.

Page 6: Living Facades

4

Leaves of plants have their effects on the surrounding air. They capture all kinds of pollutants that come from cars and industry. These pollutants are absorbed on the leafs or washed away and treated in the bio filtration process of the roots of the plants. Through their photosynthesis process, plants are able to make oxygen and capture CO2. An average-sized tree releases enough oxygen throughout one day to keep a family of four breathing, in terms of oxygen generation. To compensate for CO2 pollution each citizen needs 122 trees or 550.000 m2 of moss.

Plants are able to reduce noise. The reduction is small however; only 5dB and mainly in the higher frequencies. Living façade systems of the modular green system category act best as sound insulators.

The presence of plants on the façade means the biodiversity increases, which can be seen as a good thing. These plants can also sustain other forms of wild life by providing food sources and shelter. They also have an impact on humans. People surrounded by plants show fewer symptoms of discomfort and stress, have a lower blood pressure and heal faster. This can partially be explained by the sensitivity of the human eye to the colour green, at 555nm.

Plants are an important factor for the conservation of water cycles. This is important, because water cycles regulate the climate on earth. Plants contribute by their evaporation process, which makes them function as valves in the cycle. Thus the plants form an important solution to the Urban Heat Island Effect. Plants can also contribute to this effect, because they do not absorb solar heat and therefore living façades help provide a cooler city.

Plants also have thermal influence on the building by their evaporation processes. Further, they contribute because the air in-between the leaves insulate, wind is blocked, wind speed around the building lowers and leaves provide shades. The air near a living façade is up to 3°C colder in summer, which influences convection streams. A plant lets through a factor of 0.55^LAI of solar energy, in which the LAI is the leaf area index, the amount of leaves that is projected on the planted surface.

In order to prevent overheating of the building, 40% of the façades that face the sun should be closed. Only 5% of the glass in the façade can be exposed to direct solar radiation in summer and does not have to be shaded. In winter this can be 40%. A horizontal volume should even have a 50% closed façade according to the same calculation.

The modular green container system and the industrial felts system are more sustainable. Principle details for implementation of these systems are given in Appendix E. The modular containers can be applied best on straight surfaces and is suboptimal on curved surfaces or planes with multiple angles. The felts system is easier to use on complex shapes but is less sustainable. The choice for either one can be made on the basis of the shape of the building.

The sustainable aspects that can be influenced most with the façade are heat, bio filtration, the Urban Heat Island Effect, air quality and the water cycle. Air quality can only be influenced by the amount of plants. The others can be influenced by the details of the façade. Appendix E gives optional details to improve these aspects.

Page 7: Living Facades

5

Page 8: Living Facades

6

prefaceThis report is written as a technical addition to my SADD master graduation project on the UN Environmental Council at the faculty of architecture of the Delft University of Technology. In this project, I tried to learn as much as possible about designing a sustainable building. The aim of this research described in this report was to learn the sustainable benefits of plants and to discover design criteria that can influence my design for a living façade. Apart from the ‘green’ looks of plants I was not fully aware of the quantitative sustainable benefits that the plants could bring before writing this report.

The report is meant to be a guideline for the façade design in the process of my architectural design. The knowledge of implementing the data from this report is reviewed in the last chapter of this report.

In the making of this report, I was helped by a critical review from my mentors who lead the way to a more complete contemplation on this topic. I would therefore like to thank Siebe Broersma, Kees van der Linden and Frank Schnater for their help, time and guidance with this project.

Roel Rutgers Master graduation student Architecture & Building Technology SADD studio, Delft University of TechnologyFebruari 2012

Page 9: Living Facades

7

contents

1. Introduction 11 1.1. Background 11 1.2. Problem 11 1.3. Research question 11 1.4. Goals 11 1.5. Sub-questions 12 1.6. Method 12 1.7. Structure 13

2. Architectural concept 16 2.1. Political goals 16 2.2. Architectural appearance 17 2.3. Sustainability and the green city 18 2.4. Façade 20

3. Precedents 21 3.1. Plants 21 3.1.1. Sustainable aspects of plants 23 3.2. Vertical Greening Systems 24 3.2.1 Modular green container 25 3.2.2 Industrial Felts 26 3.2.3 Façade Greening 27 3.2.4 Vegetative tiles or stony surfaces 28 3.2.5 Comparison of the systems 29 3.2.6 Conclusion on vertical greening systems 32 3.3. Climate New York 33

4. Sustainable aspects 35 4.1. Urban agriculture 35 4.1.1 Conclusion 36 4.2. Bio-filtration 37 4.2.1 Conclusion 38 4.3. Air quality 39 4.3.1 Urban air pollutants 39 4.3.2 Air filtration by plants 39 4.3.2 Oxygen production 41 4.3.3 CO2 reduction 41 4.3.4 Conclusions 41 4.4. Noise reduction 42 4.4.1 Indoor plants 42 4.4.2 Living walls Singapore 43 4.4.3 Living walls Delft 45 4.4.4 Comparison 46 4.4.5 Conclusions 47 4.5. Biodiversity 48 4.5.1 Conclusion 49

Page 10: Living Facades

8

4.6. Social and psychological improvements 50 4.6.1 Conclusion 50 4.7. Water 51 4.7.1 The water cycle 51 4.7.2 Importance of the water cycle 53 4.7.3 Rainwater 53 4.7.4 Conclusions 53 4.8. Heat island effect 54 4.8.1 Absorption of heat 54 4.8.3 Conclusion 56

5. Heat 57 5.1. Thermal influence 57 5.2. Calculations on thermal behaviour 60 5.2.1 Model 60 5.2.2 Leaf coefficients 61 5.2.3 Ambient temperature of the leaves 63 5.2.4 Winter situation 64 5.3. Interior climate 65 5.3.1 Comfort temperature 65 5.3.2 Heat transfer through the façade 66 5.3.3 Solar radiation 68 5.3.4 Internal loads 72 5.3.5 Influence of building mass 72 5.3.6 Ventilation 73 5.3.7 Influence of greenery 75 5.4. Calculations on climate 76 5.4.1 Setup of the model 76 5.4.2 Outcome of the model 77 5.4.3 Conclusions 79 5.4.4 Evaluation of the model 80

6. Façade criteria (conclusions) 83 6.1. Comparison systems on sustainability 83 6.2. Criteria from sustainable aspects 85 6.3. Principle details 87 6.3.1 Façade division 87 6.3.2 Implementation of systems 88 6.3.3 Water and dirt 88 6.3.4. Implementation sustainable aspects 89 6.4. Influence on the building design 91 6.5. Evaluation 92

7. Implementation in Architecture (recommendations) 93 7.1. Final design 93 7.2. Choice of the living façade system 95 7.3. Implementation of the façade 96

Page 11: Living Facades

9

Literature 99

Pictures, diagrams and tables 105

A. Building systems Hort Park, Singapore 111

B. Leaf characteristics 113

C. Building volumes 115

D. Climate calculation model 116

E. Façade details 129

F. Final design 155

Page 12: Living Facades

10

Page 13: Living Facades

11

1. introduction

1.1. BackgroundIn the design project for the SADD studio Architecture of the Delft University of Technology a design was made for the fictitious United Nations Environmental Council. This organisation was conceived as a guide for governments and citizens all around the world to a more sustainable world through environmental topics. It could be a merger of different environmental and ecological programs that are already established by the UN. The merged organisation could function as an authority on ecological knowledge. The main idea of the project was to house this combination of organisations in a new annex to the UN headquarters in New York. The new building ought to be a sustainable icon that spreads a message of a greener future.The preliminary design for this building is an object formed like a landscape, which is constructed from a vegetated glass covering. This covering consists of a steel construction that holds glass panes and supports a growing medium that is positioned on the glazing beads. This growing medium could be planted with vegetation that greens the building. This form of vegetated façades or roofs will be called living façades or living roofs in this research.The aim of the project is not to create a gimmick, but to really achieve the creation of a sustainable building. For the design of this UN Environmental Headquarters it is interesting to know whether the living façade and roof really contribute to the building’s sustainable performance. This research explores the sustainable aspects of the plants to answer that question.

1.2. ProblemOn the one hand, the plants on the façade create a green image for the building and seem to be an ecology-friendly measure. On the other hand,however, it is unclear whether the plants really have sustainable properties and what those are. Besides, the possible impact its sustainable benefits have, are completely unclear. Therefore, a comparison between a planted façade and a regular glass façade would have to be made in order to understand the benefit of the plants.

1.3. Research questionWhat is the absolute contribution of façade planting around the glass of a glass façade compared to a regular glass façade?

1.4. GoalsThe goal of the research is to find out whether façade planting on glass façades has its effect on the sustainable qualities of the façade and, if so, how much planting is needed in order to sustain all the employees working in it. The ‘absolute contribution’ of this question should be found in quantities such as energy and temperature, which can be measured, calculated and compared to a normal façade.The aim of this report is to find those quantities that can define the proportions of vegetation and glazing on the façade and that can be used in the further design process. In this way, the understanding of the benefits of the plants can contribute to the design of the most optimal façade in terms of sustainability. The output of this report can give the architect an idea of the quantities of

Page 14: Living Facades

12

planting, the systems that could be used or implemented and the efficiency of different types of façade division.

1.5. Sub-questionsSub-questions are formulated to define several sustainable aspects that can be derived from the properties of a plant as found in the Precedents of this research (see chapter three).The investigation to the water cycle (question 2) leads to the influence on Urban Heat Island Effect (question 8). Next to these aspects of the plant itself, the mode of implementation and the systems for buildings have to be investigated (questions 1 and 11).

Sub questions:1. What living façade systems can be used for the assembly of the living façade

and how do they compare?2. How do plants influence the air composition and how can this be optimized?3. How does the façade influence rainwater run off and the water cycle and how

can this be optimized?4. How do plants influence the soil composition and how can this be optimized?5. Can the façade be used to grow agricultural crops for food supply?6. How does the appearance of the plants on the façade influence people?7. What is the effect in noise reduction by the green façade and how can this be

optimized?8. Does the façade contribute to the preservation of the local biodiversity?9. What is the effect of the façade on the temperature of the surroundings in

view of the Urban Heat Island Effect and how can this be optimized?10. What temperature difference does the planting of the system cause,

compared to a normal glass façade and how can this be optimized?11. How can the plants be implemented best, in order to maximize their

sustainable properties and how does this influence the technical aspects of the façade?

1.6. MethodSub-question 1 is a literature study on the systems invented to assemble a living façade. This is a broad study that categorises and defines the existent systems for living façades. (These systems will be called ‘vertical greening systems’ in this report.) With the information of this inventory, a comparison on the different kinds of systems can be made. This can lead to conclusions on the usability, efforts and shortcomings of the different systems.

The sustainable features (questions 2-10) can also be studied in literature. These issues will need to be assessed on useful numbers that can be used to determine percentages of vegetation, vegetation density and amount of glass in the façade. Where possible, the information should be focussed on the conditions in Manhattan. Data will be converted to usable figures for the building and, if possible, its location.

Question 10 will need extra physical calculations, in order to understand the influence of the shape of the building on the cooling properties of the plants. This question is of extra importance, because the planting in the given façade

Page 15: Living Facades

13

system provides shading and evaporation , which will influence the thermal behaviour of the building. This behaviour is not an add-up of the glass and the green surface, but a synthesis of both of the parts. Moreover, this topic is more important, because the main function of a façade is controlling the interior climate of a building.

Figure 1.1: Building sections

To allow calculations on building scale, four standard sections are defined for the building shape (A to E). To keep the relation with the design project, all volumes should be 100.000m3.We define the building as a 100m extrusion of a square (A, 32m x 32m); a standing or lying slab (B&C, 18m x 55m); a half circle arc (D, radius = 25m) and a trapezium (E) which is 50m wide at the bottom, 22,5m wide at the top and 27,5m high. These four typologies should give a view of the influence of the building shape on the investigated properties of the green façade. (See also appendix C)

1.7. StructureThe research will first look into the Architectural project that preceded in chapter 2. The architectural design and its appearance created a need for further knowledge on living façades as well as information that can be used to develop the architectural design. This information can be used to understand the criteria and the purpose of the living façade in its architectural context.

After this introduction, the research focuses on precedents that are of importance for the research on the façade itself in chapter 3. The first part contains knowledge about plants, the most important ingredient of a living façade. This part of the research can lead to indications of the potential of the plants, which will define the research field. Next to the knowledge about plants, knowledge about vertical greening systems and their properties is needed, in order to understand how the plants can be implemented on the façade. Then there is also a need for knowledge on the climate in New York, to make a calculation of the interior climate.

The main body of the research (chapter 4 and 5) consists of the sustainable aspects and possibilities of plants on a façade. The research looks into all impacts that the plants could have on their environment, the building and the users of the building. For reasons of usability of this research, the climate and properties of New York are used as much as possible. In chapter 5 the research looks deeper into the effect on heat. This chapter focuses on plants installed in combination with a glass façade. The combination of plants and glass leads to special thermal behaviour, which will be studied in this chapter.

Page 16: Living Facades

14

After these important aspects, criteria for the façade design are formulated in chapter 6. All sustainable aspects lead to knowledge about the systems that could be used best, of the impact of the plants and how this can be optimized in the façade. With these properties, technical detail drawings of the façade are made.

In chapter 7 the implementation of these criteria, principals and proposals is evaluated on the basis of the design process executed with the knowledge from this report. This chapter aims to investigate their usability and value and evaluate this research report in terms of value for the architecture.

The structure for the report is derived from the structure of the project that consists of many different aspects. Below, these aspects are visualised in a tree scheme that shows the origin of the aspects that are treated in this report.

Figure 1.2: Research structure

Page 17: Living Facades

15

The project comprises four broad main themes: the building design itself; the theory of green cities, in which nature is implemented in the urban space; sustainability, as a theme for both the organisation that houses in the building, and as a condition for the total design; and the political goals on sustainability and on a greener earth, for which the project functions as a statement.

On the building scale, four important sub-topics are defined. Of course, the most important topic is the architecture of the building. The architecture itself is largely defined by the living façade, a second topic, which is largely influenced by the main ‘green city’ theme and that relates to the topic of site ecology, which is also influenced by the green city ideas. The last important theme on the building scale is the sustainable solutions that give the building the sustainable character that fits the project.

The living façade is the main topic for this research report. For the façade there are three important subjects: its form, which is partly defined by architecture and partly by the optimisation of its sustainable aspects; the sustainable impact of the plants, which forms a part of the sustainable solutions on the building scale; and the technical detailing, that will define the way the façade will be assembled.

This report will focus on the creation of a program of requirement and principle detailing for the façade, through the research of the sustainable aspects of the plants on the living façade. This program of requirements should give a suggestion on the most optimal system for and proportion of the façade. It is influenced by the architectural demands and limited by the technical detailing of façade greening systems.

All in all, this scheme gives the structure for the information that preceded this research and the topics that will be discussed in this report.

Page 18: Living Facades

16

2. architectural conceptIn this chapter the architectural ideas and constraints for the building preceding this report will be discussed. They give an impression of the intentions of the architecture by which a more focussed program of requirements can be formulated in this report.

2.1. Political goalsThe architectural project on the UN Environmental Council is itself a political statement for a more sustainable world. It was founded on ideas about sustainability from the UN itself. In 1983 The United Nations convened the Brundtland Commission  to address growing concern “about the accelerating deterioration of the human environment and natural resources and the consequences of that deterioration for ecnomic and social development.” (DESA 1987) The outcome was the report ‘Our common future’ , which targets sustainable development. This laid the groundwork for the policy on sustainable development for the UN.

In 2007 the UN ratified ‘The Triple bottom line’ (people, planet and prosperity) approach and it became the dominant criterion for measuring organizational success. (Sustainability and business 2008) While the people and planet aspect of the triple bottom line are well addressed in the Economic and Social council, the Security Council and the Court of Justice; the Planet aspect is only taken care of in programs and sub-organisations (like UNEP).

This project was born out feelings of frustration in relation to environmental issues and the lack of a leading actor. Climate and waste issues are easily trivialized or underestimated by a large audience. Earlier this year United Nations organ IPCC was publicly criticized for publishing untrue facts, which convinced even more people to believe environmental problems are not to be taken seriously. The initiative calls for an empowerment of the environmental and development programs at the UN, which could be a global and objective stakeholder in the creation of a sustainable world.

The design project aims to improve the image of the ecological programs by making an Environmental Council housed in the United Nations Headquarters for Sustainability. The initiative proposes a reform within the United Nations institution that wishes to detach organs that have environmental issues as a main objective. A new combined council should be formed , which represents the third pillar of the triple bottom line for sustainable development ‘planet’, next to the already existing economic and social pillars. This new institution, like all other councils, would still function in symbiosis with the United Nations and should have as main target the propagation of a clear, condensed message to the public. Whereas few people know about the IPCC the United Nations Environmental Council should be a force to be reckoned with: it has a clear image and profound authority to safeguard and control environmental sustainability all over the planet. (The image below shows the new structure of the UN after this interference.)

Figure 2.1: new UN structure

Page 19: Living Facades

17

2.2. Architectural appearanceThe location for the UN headquarters for Sustainability is situated right next to the UN headquarters in East-midtown, Manhattan, New York. As a strategy for the realization of an icon, the choice has been made to deal with the problem of biodiversity in the middle of Manhattan by keeping the location on which the icon will be built as green a space as possible. As vegetation is scarce in Manhattan, it is extremely important to try and create new nature. The realization of a building that supports nature in the middle of Manhattan can be an aesthetically strong gesture.

Form study shows that the building distinguishes itself best from the surrounding blocks when the shape is more organic and horizontal. This led to the concept of a landscape-like building perforated by architectonic boxes. The total building is covered with vegetation to enforce the perception of the hill shape. This is the basis for the living façades and roofs design.

The landscape element in this sketch is the roof and façade structure that contains most public functions and spaces. To light these spaces, this façade should be partly translucent, opaque or transparent. This is an important criterion for the façade and roof. An impression of the façade and the architectonic volumes inside the building is displayed the picture below.

The architectural shape is located on the north side of the location. In this way, it forms a boundary to the International Territories of the UN Headquarters on the north. Also, the view from First Ave on the East River at the west side of the location is preserved in this way. At the south side of the location a space is kept free to make a north entrance to the existent United Nations Building. In the image below the red rectangle is the footprint of the building; the horizontal arrow shows the line of sight and path to the East River; the vertical arrow shows the new entrance path to the General Assembly building of the United Nations Headquarters.

Figure 2.3: Interior landscape reference

Figure 2.2: Design sketch

Page 20: Living Facades

18

2.3. Sustainability and the green cityThe concept for the architecture is based on the concept of a ‘green city’. This is the aspiration for an urban landscape in which nature is reintegrated and buildings and surfaces are vegetated as much as possible. This idea largely influences the design for the UN Environmental Council and is the root of the concept for the living façade and the roof structure that are implemented in this design.

The discussion about integration of nature in the city can be overruled by the

critique that planned greenery is not real nature and should therefore not be craved for as such. This comment often leads to the conclusion that we should not bother to facilitate a place for nature in our buildings or building materials, for ‘the city is the city and nature is nature’. This would lead to the conclusion that a living façade is a gimmick; a costly interference without use.This argument can be argued upon if we look at the map below, on which we see the human influence index on global scale:

In this map we can see that there are few areas in the world that are totally unaffected by human activities. The only areas on which humans do not have any influence, are mainly located within the polar circle, in the Amazon, central Australia, the Himalaya and the Sahara. The natural areas as we perceive them in Europe and the United states, are in fact heavily influenced by human activity. This brings us to a quote about nature from the point of view of the city planner:

Figure 2.4: Site plan

Page 21: Living Facades

19

“The decision ‘to leave nature be’ can also be considered a human production of nature as there is no solely ‘natural’ matter outside human reach or impact on the surface of the earth.” (Swyngedouw, Kaika en Heynen 2006)

The fact that pure nature, uninfluenced by human actions, does not exist, cancels the discussion about nature as a pure entity. As nature in the Western world seems to be interconnected with human planning, we can therefore consider whether to plan with the factor ‘nature’ or not, depending on the circumstances.

While more and more land is used for planned activities, the decrease of nature is often still ignored. Nature should therefore be reconsidered in architectural and urban theories. The design of the UN Environmental headquarters is inspired on Louis le Roy’s concept of giving the city back to nature (see picture of his ‘eco-cathedral’ below). In this view, the building can be the key point from which nature could reclaim the city. (Roy 2010) By giving building sites back to nature

after the building process and by planning space for reciprocation by nature the city can be made green again. “The skin of the city can be transformed into a living landscape”. (Newton 2004)In this report the sustainable aspects of living façades are explored in order to determine their value for the building and the city and to leave the conceptual discussion about nature as a definition. This can at least help to revalue the presence of plants in the built environment and thereby also revalue the living façade as a building investment instead of a mere philosophical discussion.

Figure 2.5: Map of human footprint on the world

Page 22: Living Facades

20

2.4. FaçadeIn the architectural project, a living façade is implemented in the design derived from the green city concept. The façade surface forms an extra expansion space for nature when it can be overgrown. This adds another important function to the façade next to controlling the building’s interior climate.

The design combines the glass façade with plants in order to merge with the park landscape around the building. Sustainable criteria should be used to further shape this façade and the relation between glass and plants and their

quantities. In this way, the façade can be designed as a sustainable tool instead of a gadget. The appearance for the living façade is defined in the picture below. Overall, it is defined by a straight grid of glass panes that is sometimes interrupted by a closed vegetated area.

The criteria for this façade from the preliminary design are that the façade can be used as an umbrella for the functions below. It is a hill-like shape that shades volumes and spaces underneath it. This means that it should be able to function both for different slopes and for horizontal or vertical planes. This might mean different techniques to detail the living façade may be necessary to realise the design.

Figure 2.6: The eco-cathedral of Louis le Roy

Page 23: Living Facades

21

3. precedentsBefore the report looks into the sustainable aspects of plants and how to optimize them on the façade it will look into plants, living façade systems and the climate in New York first. The consideration of plants can lead to the various sustainable aspects of these organisms , which can help structuring chapter four. By investigating what living façade systems are already available the optimization can be rendered to technical details for the façade. The preceding research on the climate in New York gives a lead for the thermal calculations in chapter five.

3.1. PlantsPlants are the most important ingredient for a living façade. Therefore, the term plant should be understood and defined very precisely. In this paragraph, the word plant will be defined and the different aspects of plants will be described.

The definition of the word ‘plant’ can be found in biology. According to this science, a plant is an organism belonging to the kingdom of ‘plantae’. In the family of plantae many species exist, varying from herbs and trees to mosses and algae. Within this family, there are three concepts of plants: ‘plantae sensu strictissimo’, ‘plantae senso stricto’ and ‘plantae sensu lato’. The last two groups include water plants and algae and will not be discussed in this report. The land plants defined in the ‘sensu strictissimo’ form the group that can be applied on the architectural concept in the project described. Plants are classified in the APGIII system for plant taxonomy, in which 350.000 species have been identified as land plants. All these 350.000 species could be implemented on a living façade.

A typical plant has one or more roots that are mostly located under the soil surface. With these roots, the plant absorbs water and inorganic nutrients. They also help to anchor the plant to the earth and store food and nutrients. Above the soil surface, the plant has one or more stems with leaves. Most plants (260.000 species) have special stems for reproduction that we call flowers.

Land plants, with few exceptions, live and grow by photosynthesis from carbon dioxide. For this process, sunlight is absorbed to add energy to a chemical process with the nutrients that the roots of the plant absorb. In the photosynthesis reaction, a chlorophyll molecule is used to absorb light from the ultraviolet and infrared range, which causes the plants to look green. A plant does not strictly require soil to live. It only needs water with dissolved minerals, light and carbon dioxide to live and grow. The way to grow plants without soil is

Figure 2.7: Appearance of the living façade

Page 24: Living Facades

22

called hydroponics and uses an mineral nutrient solution without a solid growing medium or with an inert medium such as gravel or mineral wool.

Over half of the plant species reproduce by seeds. A seed is an embryonic plant enclosed in a seed cover that usually also contains food. Some seeds are enclosed with a hard or fleshy structure called fruit. Other means for reproduction of plant species are spores, rhizomes, corms, tubers, bulbs, cuttings, grafts, bulbs and buds. Many of these fruits are a food source for humans and animals.

Page 25: Living Facades

23

3.1.1. Sustainable aspects of plantsFrom this description of land plants we can derive the influences plants can have on humans around them and the environment they live in. We know that they react with air, water, light and nutrients in the soil in order to keep themselves alive, grow and reproduce. This means the plants play an active role in the chemical composition of air and soil. By these chemical processes, they grow and form seeds and fruits that can function as food for humans. In a passive way, the plants form green objects that, like any other object or material, influence sight, sound and warmth. Next to these properties, the plant itself is present in city ecology. This adds the topic ‘biodiversity’ to the passive influences.

Influence on the human environment:

Active: Passive: ■ Air composition ■ Appearance ■ Water ■ Sound ■ Soil composition ■ Warmth ■ Food production ■ Biodiversity ■ Light

These aspects and their influence will be further investigated in chapter four to determine their sustainable potential. Warmth will be investigated in more detail in chapter five.

Figure 3.1: Influences of plants

Page 26: Living Facades

24

3.2. Vertical Greening SystemsIn the current building industry, several different types of living façades are used, of which the most used ones can be described in four categories. First is the modular green container, which uses panels with a growing medium mounted on a construction frame. Second is the industrial felts systems which uses felts as a growing medium and is mounted directly on the façade. Then there are façade greening systems that use climber plants that grow over the façade. The last category are the vegetative tiles or stony surfaces, which consist of rough stone materials that allow plants to grow in holes and cracks.

These are four significantly differing façades that all have their specific properties. There are also many other options when making a living façade, but most of them can be described as hybrids or derivatives of these four. For the cause of clearness in the report only these four categories will be compared. This chapter will give a description of all these types of façades in order to be able to compare them and understand the influence the systems have on the sustainable aspects described in this research.

Page 27: Living Facades

25

3.2.1 Modular green containerThis is a container filled with a growing medium, often just natural soil, that is attached to a construction frame on the wall of a building. The containers generally have slats inclined in an angle that hold the soil. Some systems make use of a foil over the containers to keep the soil in place. There are several standard sizes and systems to be found on the market. Usually these panels are square in measures as 30x30, 50x50 or 60x60 cm. Custom sizes can often also be delivered. The system is quite heavy due to the soil and weighs about 200 to 300 kg/m2 (Gerhardt en Vale 2010).

Before installation, the plants have to grow several weeks in horizontal position to strengthen their roots. After this period the panels can easily be attached to the construction frame, often with a customized quick-fastener system. The plants can be watered by hand, naturally, or by an extra irrigation system. For steep surfaces the last solution is recommended. The plants are prevented from overwatering by little holes in the sides of the container that let the surplus of rainwater out.

As the soil gets depleted by the plants over time, the soil will need to be replaced after a few years.

Alternatives for this system are, for example, frames with planter pots, or frames clad with sacks of soil. One could think up many solutions to add an amount of soil to a frame.

Figure 3.2: Construction frame for G-sky containers

Figure 3.3: ELT living wall panel

Figure 3.4: Vegetated living wall panel

Figure 3.5 Habitile system Figure 3.6: Mosstikapanel Figure 3.7: Schiavello

Page 28: Living Facades

26

3.2.2 Industrial FeltsThis system is based on the idea that plants only need water and nutrients and therefore soil could be left out of the system. In this system, the plants root into a fibrous material. For exterior façade cladding many building projects use Felts. The material is mounted directly on a waterproofed façade.

The entire living wall system has a depth of 40 mm and weighs roughly 30 kg/m². (Gerhardt en Vale 2010)

Before assembly, the waterproofed façade is first clad with two or more layers of a fibrous growing medium. Through this growing medium, an irrigation system of plastic tubes is mounted. The plants are planted in this system by making incisions in the upper layer(-s) and placing the roots of the plant in the cut.

The plants are provided with water and nutrients by the irrigation system, which keeps the layers of fabrics, and thereby the roots of the plants, moist. This system thereby prevents the plants from dehydration. The irrigation system is often made up out of little plastic tubes that can also be found in aquarium installations. This part of the system is most crucial for the façade, because it determines the fertility of the system.

Plants can last long in this system, because of the artificial nutrition, but there is little chance of spontaneous vegetation due to the lack of soil.

Coconut fibre mats or Rockwool can be used as an alternative for the felts. There are also solutions with different growing media on the market such as facades with Aquadyne blocks. Often these solutions are made from more artificial and less flexible media than felts. This report therefore uses felts as the best example of an artificial growing medium.

Figure 3.8: 3D section felts system

Figure 3.9: Vegetated felts detail drawing

Figure 3.10: Technical drawing felts system

Page 29: Living Facades

27

3.2.3 Façade GreeningA façade greening system consists of a trellis structure that is attached to the side of a house or building, which allows plants to grow from the ground up or from planter boxes. This means that the plants are not really growing on the building, but over the building.

The height of the façade that can be covered with this system is dependent on the used climber plant. The most used plant for these systems is the Hedera Helix (ivy), which can grow 20 to 30 meter high, with an average of 1 to 2 meters per year. A choice for a suitable climbing plant can be made from a wide range however, with plants varying in average height from 1 to 25m. (Zimmermann 2008) In general, this system is very light. A steel trellis structure weights only 1 to 3kg/m2. The plants adds a little weight to this, depending on the size and species. The total is much lighter than the previous two systems.

To ‘green’ the building with this system, a construction for the trellis structure is added to the façade. Then the trellis, often a steel net or steel cables, is mounted on this construction. Climber plants are then planted on the ground or distributed in planter boxes over the façade.

Most climber plants, like Ivy or grapevines, do not need a lot of water. Most systems are therefore implemented without irrigation.

Figure 3.13: Hedera Helix

Figure 3.11: Section trellis structure

Figure 3.12: Facade greening

Page 30: Living Facades

28

3.2.4 Vegetative tiles or stony surfacesA wide range of mosses can grow on nearly every surface that is a little bit porous or rough, provided that there is enough moisture around to keep these plants alive. These plants do not have roots but a kind of cellular anchors to keep themselves attached to a surface. A system in this category is the so-called gabion: a metal cage with stones loosely piled in it. The cages can be used as large blocks to make a wall.

Over time, plants can root in between the rocks thanks to dust, water and compost that accumulate in between the rocks. In this way the system grows green over time. The gabion system is capable of sustaining more plants, because of the possibility for the roots of plants to grow through the staple of rocks. It is so fl exible that even trees may grow on it. This is a risk however, because the large roots might destroy the system in time, although this takes decades.

The wall preferably has to be in the shade to avoid dehydration of the plants on the surface. A system that sprinkles water on the surfaces can improve the process. (Schenk 2004)

Figure 3.14: Moss on concrete

Figure 3.15: Gabion wall as river bank

Figure 3.16: Gabion

Page 31: Living Facades

29

3.2.5 Comparison of the systemsOn the basis of the given technical properties a comparison between the different systems can be made. The systems will be compared as far as weight, vegetation density, maintenance, installation, complexity and water use is concerned. The comparison is made on the basis of economic advantages and expediency to vegetate a façade since the benefits in terms of sustainability are yet to be researched.In terms of weight a lightweight system will be judged as more positive than a heavyweight since it will require less construction and less transport and will thereby cost less (--= heavy; ++=light). Vegetation density will be judged more positively when more plants grow on a system per square meter, as it is assumed that the aim of a system is to facilitate plants as much as possible (--=not dense; ++= very dense). Maintenance will be judged more positively when the system requires less care, since this will be more convenient for the building user and will cost less after the building process (--= requires a lot; ++= requires nothing).Installation will be judged more positively when the system can be applied more easily, since this will lead to lower installation costs (--= difficult; ++= easy).Complexity will be judged as more positive when a system is less complex, since it is assumed that a system can be assembled more easily and will therefore cost less effort to make (--= very complex; ++= very simple).Water use will be judged as more positive when the system uses less water since more water will lead to more costs for the irrigation system and the water itself (--= uses a lot of water; ++= water saving).

The comparison:Modular green system

Industrial felts system

Façade greening

Vegetative tiles or stony surfaces

Weight - + ++ --Vegetation diversity ++ + 0 -Maintenance -- + - ++Installation - -- ++ 0Complexity 0 - + ++Water use + -- ++ -

In terms of weight, the façade greening system is most favourable. This system only needs a trellis structure to support the plants that can grow from the ground up. In this way, it cancels out the growing medium that is present in all the other systems. Only if a building gets a lot higher than 30 meters does the growing range of the plants not suffice. This is only the case if the building shape of a standing rectangle is chosen in the architectural design. In that case, a row of hanging planter boxes halfway the façade will be needed. This is still less added weight to the building than the other systems would need. The industrial felts system is the second lightest system. The felts or other artificial growing mediums are very light in weight. However, they do need a supporting structure of a plate material and an irrigation system over the whole surface , which makes them heavier than the façade greening.The modular green system is heavier, because of the use of soil and a steel

Page 32: Living Facades

30

frame to mount the containers on. This system can be combined with irrigation to lower the maintenance burden , which makes it even heavier.The vegetative tiles or stony surfaces systems are rated as the heaviest system and as such, it rules out every option to make a light building. The system needs the heavy stones, tiles, or concrete by definition and therefore has a lot of mass.

The vegetation diversity is most optimal in the modular green system. It can sustain almost every plant form, because of the use of soil. Only the slope of the façade influences the system on this point, because some plants are not capable of growing on a vertical surface, even after they are full-grown.The industrial felts system is also suitable for many different plants, but not every plant is able to form aerial roots. Moreover, just as in the case of the modular green system, the slope of the façade also limits the choice of the plants.The façade greening system supports only climbing plants, but this is still a large plant group. The planter boxes at the foot or halfway of the façade can also support other plant forms.The vegetative tiles or stony surfaces systems supports mosses, which make up a very large plant group with approximately 12.000 species. Systems like the gabion system can support even more species if they get filled with humus over time. The normal stony surfaces, even if they are irrigated, are very fragile though. They cannot be exposed to normal amounts of sunlight, because of the risk of dehydration of the surface and the plants by evaporation. This makes the system less likely to support a lot of plants and therefore the score for these systems is also the lowest. This may not be totally true for the gabion system, especially not after the first decade of its lifetime.

The vegetative tiles or stony surfaces do get a good score, as far as maintenance is concerned. Because the wall is less likely to be overgrown the vegetation needs less care. Again, the gabion system is an exception to this rule, because the plants in this system, especially trees, can damage it over time. The first decade of its existence it is likely to be maintenance free, though, and overall, the periods between maintenance can be long.The maintenance of the industrial felts system also scores high. This system keeps the plants moist and feeds them continuously with nutrients , which lowers the chance of plants that dying and having to be replaced for aesthetical causes, provided that the irrigation system works well and keeps the total felts system moist. However, in practice the irrigation systems behind the system’s panels are shown to fail a lot and therefore the system needs some maintenance over time.The climber plants of the façade greening systems tend to overgrow total façades. If the façade is not maintained and the plants are not pruned enough, their stems could get into places in which they do not belong and damage the façade. This makes it a maintenance intensive façade.The modular green system scores worst on maintenance. Main causes are the biodiversity and the soil in this system. The system can support many species of plants, but some of them are not wanted, because they get too big, for instance, and have to be pruned or removed from the façade. Besides, in a system without the optional irrigation the soil gets exhausted after a certain period and has to be replaced. This is a very arduous operation , which makes it the most

Page 33: Living Facades

31

maintenance intensive façade. This can be improved by installing an irrigation system that provides the soil with new nutrients and extra water.As far as installation is concerned, the façade greening system scores best. This is partly caused by its low weight. Furthermore, it is a really low-tech system, which only needs a trellis structure, provided that the planter boxes can be installed on the ground around the building. Most façade designs can easily be adjusted to attach the cable nets that can function as a trellis structure. The only negative point could be the installation of the plants themselves: it takes a while before they grow over the full building. The average growing speed is about 2 meters per year , which can be increased a little by using a strong fertilizer.The score for the vegetative tiles or stony surfaces is set to neutral. If the building design already has an outer surface of stone or concrete, only an extra irrigation system would be recommended. This does not take a lot of extra installation work. If, however, the total façade has to be clad with an extra material, this is not an easy system. For instance, the gabions are not easy to combine with the glass façade in the preliminary design preceding this report. In a design with a concrete outer wall in the shades, however, it will not take very much extra effort to turn it into a living façade. In that case simply spraying some water over the façade is enough.The modular green façade scores a minus, for it is a system that needs an extra steel frame installed to attach the containers to. An irrigation system can make this system even more complicated. In this case, a more precise system is necessary that feeds every plant in every container. The felts system is the least easy system to install. Firstly, the irrigation system behind the panels is very delicate and has to be very precise to keep the whole façade moist enough to prevent the plants from dehydration. Secondly, the plants have to be inserted into the felts one by one to green the façade.

The installation problems make the industrial felts system a very complicated system. Next to the irrigation pipes, it also needs a pump and water with nutrients flowing through it. Also, the felts (growing medium) need to be a high tech material that cannot rot. Altogether, this system is highly complicated and is hard to design and assemble.The score for the modular green system is neutral, because the steel frame and containers are relatively low-tech and easy to make and assemble, but an irrigation system can make this system much more complicated.The façade greening system is less complicated with only a simple steel cable net attached to the façade and some planter boxes on the ground or somewhere halfway the building. The tile or stony systems are even simpler, since only a surface and a simple irrigation system for moisture would be necessary.

As for water use: the industrial felts system is totally dependent on extra water. If water (with some nutrients for the growing process) is not provided, the roots of the plants will dehydrate and die , which will cause the plant to die as well.The vegetative tiles need less extra water, but do need some, especially in a dry place like Manhattan in summer time. Both the façade greening and the modular green system need even less extra water. The first is the most economical, because the climber plants in general do not need a lot of water. The containers of these systems have the advantage that they can store some rainwater. This causes both to have a positive score.

Page 34: Living Facades

32

3.2.6 Conclusion on vertical greening systemsOf all the systems, the façade greening system has most advantages. It is light, it is simple and low-tech, it is easy to install and it does not need a lot of water. It is a system with a lot of economic advantages and it is very efficient in making the appearance of the buildings look green.It does, however, have two disadvantages. The first is the amount of maintenance the façade needs. Especially when the façade slopes, the plants can tend to leave the trellis net and hang onto the façade. The plants can then creep over the façade and reach unwanted places and might even do damage by blocking ventilation mechanisms, growing into cavities or polluting windows. This is less of a problem when the façade slope is more or less vertical. The second disadvantage is the fact that only climber plants can grow on this system. This conflicts with the idea of nature reclaiming the city, because nature can reclaim the systems containers that are on the ground and might even be here and there on the façade; but nature cannot reclaim the façade itself. Only the climber plants can grow there and otherwise there is still no plant life possible on the façade.

If this ‘green city’ idea is more important than anything else, the modular green system would be a better choice. For the simple reason that the system uses soil and is, thereby, able to cover the fragile roots and seeds of plants. This is also the case for the industrial felts system with its growing medium and artificial moist but to a lesser extent. The modular green system is less complex and easier to install than the industrial felts system. Only disadvantages here are maintenance and weight. The 244kg/m2 mass needs quite a big construction and maintenance is burdensome. This last aspect can be eased by making an irrigation system. However, even then, the façade would still need pruning twice a year or even more. The industrial felts system is a better option when a high-tech, and thereby more expensive, project is not a problem. It would need less maintenance and the construction can be slimmer thanks to its 30 kg/m² mass.

Altogether the choice should be made between really making space for nature in the city and only creating a green image. In the first case, a lot of effort would have to be made to give nature a place and this can result in very complex and water demanding system or a very heavy and maintenance demanding system. The other option is an easy system , which will be quite easy to realise and will provide the building with leaf coverage.

Page 35: Living Facades

33

3.3. Climate New YorkIn order to be able to make calculations for thermal behaviour for the façade some data on the climate in New York are needed. These data are also usable for decisions on irrigation of the plants or to estimate the suitability of the city for plants. In general, this information gives a better view of the circumstances in New York.

Measured at: Latitude: +40.71417 (40°42’51.012”N) Longitude: -74.00639 (74°00’23.004”W) (National Weather Service 2010)

Manhattan is located at +40.7° latitude , which means the sun will be maximally at 72.7° above the horizon in summer and 25.7° above the horizon in winter. The climate in New York is approximately the same as in the Netherlands, but it is a little more extreme. Temperatures are higher and lower, there is more precipitation and there is a higher wind speed, as can be seen in the tables on the left.

The warmest month in Manhattan is July with a daily mean temperature of 24.7°C, an average high of 29°C by day and an average low of 20.4°C by night. The temperature record for this month is as high as 41°C. The coldest month in Manhattan is January with a daily mean temperature of 0.1°C, an average high of 3.3°C by day and an average low of -3.2°C by night. Temperature records for this month are as high as 22°C and as low as -21°C.

Throughout the year 1262.1mm precipitation can be expected with an equal spread over the year, which implies about 110mm of precipitation every month. This precipitation is spread over an average of 120.7 precipitation days. In winter months

Page 36: Living Facades

34

snowfall can be added to this. The average snowfall is 713.7mm per year on an average of 10.9 snowy days.

Throughout the year about 35% of the days is clouded, 35% is partly cloudy and 30% of the days is clear of clouds. October is the only month that these percentages drop by 5 to 10% and there are more cloudy days. Sunshine fluctuates between 50% in wintertime and 65% in summertime.The wind speeds can be as high as 5.0m/s in winter and 4m/s in winter. Humidity is about 70% throughout the year.

For the plants these data are an important factor. Temperatures in summer cause the risk of wilting, while the temperature fluctuations in spring may cause the plants to grow or flower too early.

The most important factors for plants however, are quite stable. These are sunshine and rain. Over the year the plants are ensured of enough water and enough rain. This implies that Manhattan, besides being a crowded bourough, can be a good place for plants after all.

Page 37: Living Facades

35

4. sustainable aspects

4.1. Urban agricultureAs observed in chapter 3.1 plants can provide food for humans. In this paragraph we will take a look at the possibilities to use the living façade as a food supply.

The urge to plant crops in alternative places is present. “The world population is expected to reach 9.2-billion in 2050, which is approximately 3-billion more mouths to feed than there are today. Already 80% of the land suitable for growing crops is being used and the jury is still out on how much of that land will remain arable as climate change sweeps the globe.” (Sky’s the limit 2009) This means we will have to invent new ways and new places to grow our crops. One way is the urban farm: the integration of farm land in our urban landscape. In this way, we eliminate the transportation between producer and consumer and optimize our urban environment.

Living façades can play a role in this problem as a system to grow our crops on. One way of doing this, is to create a double skin façade with vegetables inside the cavity planted on hydroponics. The double skin façade in this system can reduce energy costs of the building by 30%. The glass cavity works as a greenhouse for the plants and can be an efficient farming installation. (Arup Engineers 2009)(See picture on the right)

Another possibility is to grow the crops on the façade, as it is done in ‘The farmer’ project. It is stated in this project that the target market for such a system would be food enthusiasts that form 14% of the American market and mainly live in metropolitan areas. The vertical farm here is an investment to reduce costs on shipping and farm footprints. The output would be fresh crops and community presence. (Greene 2009) Another project in this range is the Eathouse by ‘de Stuurlui’ and ‘Atelier GRAS!’, an experimental vertical farm that is made to seduce visitors of the garden it is placed in (see picture on the right).

Looking at the modern agricultural industry, efficiency is key however. Crops have to grow fast, be planted and harvested mechanically, and they are fertilized and irrigated with scientific precision. However, if crops are planted on a façade,

Figure 4.1: Cavity farming

Figure 4.2: Eathouse

Page 38: Living Facades

36

the planting and harvesting becomes a very delicate process , which cannot be done mechanically. Also, insolation of the crops will not be optimal. This constant labour on the façade can cause nuisance and discomfort to the user of the building. This makes farming on the building façade suboptimal.

In most reports, the conclusion that efficiency is key, leads to urban farming towers that can deal with the crops most efficiently. These towers could provide food for large amounts of people. “Current research profiles a possible enterprise to feed up to 50.000 people based on a caloric intake of 2,200 people, a staple built up from the Centre for Nutrition Policy and Promotion’s dietary requirements and 19 floors on a 250.000 square foot area, or 43 floors on a 90.000 square foot area. This would include the growing of

(the most nutritious fish) Tilapia in tanks, and breeding chickens for mainly egg production.” (Bosschaert 2008) These amounts of square feet equal an amount of 360.000 - 440.000 m2 in total; or an amount of 7,2 – 8,8 m2 per person.

For the 600 people working in the UN environmental council an amount of 4.300 – 5.300 m2 would equal such a system, provided that the efficiency of the tower can be maintained. It is unlikely that this efficiency can be achieved on the façade of the building. Also, at least half of the façade surface would then be needed as urban farm.

4.1.1 ConclusionCompared to a glass façade, a living façade could make an extra effort in food production. Crops can be grown in a hydroponics system, such as the industrial felts system, which can be optimized for certain crops. A modular green system would also be suitable, as it can function as traditional farming land. However, this system has a bigger chance of depletion, because the nutrients in the soil are hard to refresh. Other systems are less sufficient for agriculture. Still, also in the containers of the modular green system, the planting and harvesting process is quite delicate and cannot be done mechanically. All together, the façade is not very suitable for agriculture, because of the need for efficiency that this aspect entails. It would be best to design another solution in terms of an urban farming tower. In that case, an amount of 7,2 to 8,8 m2 per person would suffice for 600 people. On the façade, the amount is likely to get a lot bigger and to take up at least half of the surface of the building volume. The aspect ‘Urban Agriculture’ will therefore get a low priority in chapter 6.2.

Figure 4.3: Efficient farming

Page 39: Living Facades

37

4.2. Bio-filtrationOne of the most important sustainable influences of plants is bio-filtration. The natural environment has all kinds of mechanisms to deal with pollution. Research shows that “the removal and disposal of hazardous waste is eliminated through a completely natural method” by the micro-organisms living between the roots of the plants. (Livingwall pdf 2004) The plant absorbs water and in this way transports liquefied pollutants to its roots where microorganisms break them down to nutrients that the plants can use for growth. This process is called phytoremediation and degrades or eliminates all kinds of solvents, pesticides, metals, oil and other contaminants. By this mechanism, the plants can function as a bio filter in a living façade.

In the phytoremediation process a range of processes by the plants is distinguished:

■ Phytoextraction: uptake of substances in the plant biomass ■ Phytostabilization: reducing the mobility of substances in the environment ■ Phytotransformation: modification of the substances by the plant metabolism ■ Phytostimulation: degradation of contaminants by enhancement of soil

microbial activity, typically associated with roots ■ Phytovolatilization: removal from soil or water and release into the air ■ Rhyzofiltration: filtering water by a mass of roots; the pollutants

remain absorbed in or to the roots

This cleansing function can be used in a system for biological treatment for waste water. By implementing such a system, the amount of waste water from a building can be brought back to near zero. A bio-filtration system consists of a basin with plants, in which all grey and black water from the building flows. The principal components are pre-treatment grasses, woody and herbaceous plant species, a surface mulch layer, a planting soil medium and a sand layer with under drainage in a gravel bed. (Schundler 2010)

The water filtration system can be implemented with water flowing horizontally or vertically (see pictures below). A horizontal system needs 3-10m2 per person with a depth of 60-80cm; a vertical system needs 1,5-5m2 per person with a depth of 80-120cm. Minimum measures suffice for grey water, maximum for black water. (Hegger 2008)

Figure 4.4: Filtration systems

Page 40: Living Facades

38

The moistier the soil is, the more pollutants are dissolved and the more effective this process is. This makes wetlands the most effective bio filters.

Implemented in New York, the bio filters can treat the enormous amounts of waste water of the city. “Currently, the city throws 5.3 billion litres of treated waste water into the rivers each day” (New York news and features 2007)The total consumption of safe drinking water in New York city is 4,9 billion litres per day from 19 reservoirs and three lakes outside the city. (DEP 2007) Together with the run-off from rain and snow and the consumption of products such as bottled water and other drinks this forms a waste water flow. The usage of drinking water can be limited by treating and reusing this waste water on site.

A system to treat waste water can be implemented in planter boxes on the façade or on larger areas on the roof. The planter boxes on the façade can be especially suitable for the horizontal system with the waste water flowing along the façade. The system on the roof or on more horizontal surfaces is more suitable for a vertical filtration system. The area available for the bio filtration system is larger on the horizontal planes than on the vertical planes, because the planter boxes cannot be very broad, due to the loads they will add to the façade.

The grey water from the building is not the only pollution that the plants can filter. Rainwater also washes away many pollutants present in the city. Thereby, they are directly flushed into rivers and seas. By implementing more green surfaces in cities, plants can deal with these pollutants in rainwater. Over 95% of cadmium, copper and lead can be taken out of rainwater and 16% of zinc. Nitrogen levels also fall dramatically. (Johnston en Newton 2004) These numbers can apply to every living façade that has the possibility of absorbing rainwater for treatment by the plants and the micro-organisms amongst their roots.

Overall, the implementation of plants seems to lead to all kinds of possibilities for the break down or capture of contaminants that are unwanted in the city. Therefore, the phytoremediation is an argument to implement a living façade. Making this living façade capable of filtration of grey water is an extra step to maximize its function.

4.2.1 ConclusionFor the 600 people working in the Environmental Council we would need an area of 3.000 to 6.000 m2 for filtering grey water. A vertical system can be made on the roof and a horizontal system can be made along the façade.

For the treatment of soil and rainwater flush-off the amount of plants in the area should be maximized. It is most important that the rainwater can be absorbed in a growing medium. This makes the modular green system most suitable. The vertical greening system can also be suitable if the growing containers form a trench around the building that can intercept the rainwater run-off from the façade

Page 41: Living Facades

39

4.3. Air qualityNext to the cleansing of water, plants are also capable of cleansing air. In this process, fine particles from the air are captured on the leaves. The interaction of the plant with the air around it will be discussed in this paragraph.

4.3.1 Urban air pollutantsUrban air pollution arises mainly from the burning of fossil fuels. Primary emissions include: oxides of carbon (CO2 and CO), nitrogen (NOx), sulphur (SOx), Benzene, Toluene, Ethylbenzene, Xylene, ‘PAHs’ (polyaromatic hydrocarbons) and metals and ‘fine particulates’. All these emissions have a proven negative effect on human health. Secondary products are also formed after further photochemical reactions in sunlight. These include ozone (O3), peroxyacetyl nitrate (PAN) and ‘smog/haze’ (from the mixture). In the drawing to the right we can see the causes and effects: (1) greenhouse effect, (2) particulate contamination, (3) increased UV radiation, (4) acid rain, (5) increased ground level ozone concentration and (6) increased levels of nitrogen oxides.The short-term health risks of this air pollution include asthma, strokes, heart attacks, and sudden infant death syndrome. Longer-term effects include low birth weights, some cancers, cardiovascular problems, and schizophrenia and other mental illnesses.

4.3.2 Air filtration by plantsPlants have been shown to absorb and degrade all types of urban air pollutants, thereby reducing air pollution levels. A single tree with a trunk circumference 67cm, for instance, removes 90kg of carbon dioxide, 0,5kg of ozone, and 0,9kg of sulphur dioxide and nitrogen dioxide particulates every year. (Nowak en Rowntree 1994) Research shows that trees in a parkland setting can filter out up to 85% of suspended particulates. The percentage is reduced to approximately 40% in the absence of foliage on deciduous trees in winter.

The leaves of climbing plants provide a large surface area capable of filtering out dust (see picture below), pollutants and possibly even viruses. (Johnston en Newton 2004) Every plant has these abilities of cleansing air. The amounts of pollutants that can be taken from the air depend on the plant species, leaf size, metabolism and the texture of the leaves. Overall, plants with hairy leaves prove to be better in capturing fine particulates and metals from the air. These particulates are eventually washed away from the plants by rain or compost into the ground when the leaf dies. The particulates are then taken care of in the bio-filtration process that was described in the previous chapter.

Figure 4.5: Air pollution

Figure 4.6: Pollution accumulating on plant leaf

Page 42: Living Facades

40

In the images to the left we can see the average concentrations particulate matter with an aerodynamic diameter of less than 2.5 micrometres (PM2.5), the concentration Sulphur dioxide (SO2) and the concentration Nitrogen dioxide (NO2) in Manhattan for the winter of 2008-2009. (Concentrations in winter are usually higher and therefore of more importance in relation to public health) The figures show variations in concentration of two times or greater dependent on building, population and traffic density. (Department of health 2009)

It is certain that an increase of vegetation in Manhattan would partly solve this problem. Exact calculation of the amount of greenery needed, would require a complex dynamic model that includes factors such as wind, spread of greenery, spread of concentrations and dry deposition kinetics. Such an exact model seems not have been made yet.

What is known about air filtering and its effectiveness, is that the air flows can bend around the green obstacle and thereby do not flow through the plants. The filtering effect can be maximized by making thin strips of greenery perpendicular to the wind direction to allow flows through them. (Schildwacht 2008) With this form more air will flow through the plants and more air will be cleansed.

Figure 4.9: Nitrogen dioxide NY

Figure 4.8: Sulphur oxide NY

Figure 4.7: Particulate matter NY

Page 43: Living Facades

41

4.3.2 Oxygen productionNot only is it important to have clean air, but also are our lives dependent on oxygen, a gas produced by plants. Oxygen is formed in the photosynthesis process in which plants use sun energy to make glucose from CO2 and H2O: (CO2 + H2O → C6H12O6 + O2) (White 2006)

Solar energy is used to split the H2O molecules. It is about 2% of the incident radiation to be trapped and used in photosynthesis. (White 2006) The reaction then continues as a ‘dark reaction’ in the so-called Calvin cycle in which the plant binds CO2 and produces its food. In this process, the plant makes an oxygen molecule for every combination of a CO2 molecule and an H2O molecule. According to American Forests, an average-sized tree releases enough oxygen throughout one day to keep a family of four breathing. (Moll en Young 1992)

4.3.3 CO2 reductionWe can also notice that in the process of photosynthesis CO2, a greenhouse gas, is removed from the air. Quantities vary with the intensity of photosynthesis in the plant. For moss this is about 20gr CO2 per square meter per day, for example. In comparison: a busy road produces 14gr CO2 per square meter per day (Hunk Design 2009). For an average plant, the daily 10g growth of dry matter per m2 uses 1g of nutrients, 80-90g of water and about 14g of CO2. Water is a relatively large component in this process and limits the capacity of plants to bind CO2. (Kravcík, et al. 2007)

The New York citizen produces approximately 11 tons of CO2 each year per person. (New York Energy Portal 2005) Half of this amount is produced by transportation only. To compensate for this amount each citizen would need 122 trees, 785700 average sized plants or 550.000 m2 of moss (21,75 times the site surface).

4.3.4 ConclusionsFor the filtration of particles of air pollution, the amount of green preferably has to be maximized. With the current knowledge it is, however, not possible to determine the exact amount of living façade needed.

In terms of oxygen generation, an average-sized tree releases enough oxygen throughout one day to keep a family of four breathing. Plants should be especially present near busy roads to capture the car emissions that are hazardous to our health. A total of 150 trees or 100.000 plants or 190.000 m2 of moss would be needed to generate oxygen for all of the building users.

Each citizen needs 122 trees, 785.700 average plants or 550.000 m2 of moss to compensate for CO2 pollution. The site is hence 13.000 times too small to compensate for the people working inside. Maximisation is therefore preferred on this aspect.

Figure 4.10: photosynthesis process

Page 44: Living Facades

42

4.4. Noise reductionPlants can absorb, reflect and diffract noise and thereby make the built environment more comfortable. On an urban scale, vegetation is often used as a sound barrier. “Shrubs, trees and berms are often used as natural noise blockers.” (ATCO 2001) The effect appears to be dependent on the plant type, planting density, location and sound frequency.

4.4.1 Indoor plantsThe absorption coefficients have been defined for a number of indoor plants by experiments in a reverberation chamber by Costa. These numbers include a pot with a diameter of 350mm and a height of 350mm and are averaged for multiple tests. (Costa, Constructive Use of Vegetation in Office Buildings 1995)

Absorptions by Vegetation 125 to 4k HzHz 125 250 500 1k 2k 4k

Plant m3

Ficus Benjamina 0,149 0,050 0,120 0,180 0,210 0,230 0,360Howea Forsteriana 0,144 0,120 0,093 0,050 0,133 0,130 0,263Dracaena Fragrans 0,127 0,1 0,1 0,09 0,105 0,145 0,165Spathiphyllum 0,057 0,085 0,07 0,065 0,095 0,16 0,305Dracaena Marginata 0,139 0,105 0,045 0,09 0,065 0,11 0,305Schefflera Arboricola 0,139 - 0,13 0,06 0,22 0,23 0,47Philodendron 0,149 - 0,23 0,22 0,29 0,34 0,72Bark mulch 1 m2 0,05 0,16 0,26 0,46 0,73 0,88

It is shown in the table that plants absorb more sound at the higher frequency ranges, which is a common phenomenom for materials in acoustics. The absorption coefficients are calculated with an estimation of plant volume, which does not describe the plants used very accurately. It is likely that these numbers were calculated using Sabines formula on an imaginary cilinder or box volume around the plants, but unfortunately the calculation method is not described in the research paper. Furthermore, Costa measures single plants in a pot, instead of living façades. The measurements do show that large differences in absorption can exist between different plant species.

Figure 4.11: Indoor plants in table order

Page 45: Living Facades

43

4.4.2 Living walls (Singapore)There has been research that measures acoustics of living façades by the National University of Singapore. (Wong en Tana, Acoustics evaluation of vertical greenery systems for building walls 2010) These scientists worked on measuring the insertion loss and sound absorption coefficient of eight different building systems. (See appendix A for their descriptions)

The insertion loss was measured by microphones 1.5 meters above the ground 1m in front and 2m behind the walls. The results for the three microphones behind the wall were averaged to tone down diffraction differences. The plants were tested on a frequency range of 63-10kHz. Results, or insertion losses, were calculated from the subtraction of noise passing the test case walls from the noise passing a bare concrete wall without vegetation and thereby the noise reduction is obtained. (see picture above)

The insertion loss of the plants is defined as follows:

Figure 4.12: Test mounting

Figure 4.13: Calculation of insertion loss

Figure 4.14: Insertion loss results

Page 46: Living Facades

44

The results are divided in four frequency zones: A, B, C and D. In the results, we see that some of the systems perform better in the A and B regions and others perform better in the C and D regions.

System 2 has the best peak performance of all systems, a 9.9dB loss at 700Hz, which is strange, because this system is the vertical greenery system with greenery growing on a trellis. The explanation for this could be that the plants are growing in quite big pots of 0.61m thick, placed on the ground. System 4 has mostly plants with small leaves and moderate density, resulting in almost zero insertion loss. System five has an air gap between the system and the concrete wall resulting in more insertion loss with a peak of 7dB.

Some of the systems show a negative insertion loss of up to 5dB in the results. The authors do not give an explanation for these negative losses. These could be explained by the fact that sound can bend around the walls through diffraction. However, this hypothesis cannot be confirmed with the given results, in which the measurements of the separate microphones are not included.

When planting is equally distributed on the wall to cover it completely, performance of the system is better. Biggest insertion loss is mostly measured around the 700Hz band. The substrate in the systems is concluded to do most of the absorption.

In the same research there was also a test performed on a greenery system in a reverberation chamber. Nephrolepis Exaltata (Boston Fern) was used for this

experiment and was placed in pots on wooden racks. (see picture on the left)

140 pots of plants were defined as covering 100% of the wall with plant. 100 and 60 plants were defined as 71% and 43% cover.

With the results of this reverberation experiment the sound absorption coefficient for this living wall was calculated and compared to other building materials:

Figure 4.15: Reveberation chamber

Page 47: Living Facades

45

The living wall specifically absorbs sound in the range of 500Hz – 2KHz. There is more difference in absorbance between the different covering percentages at higher frequencies. The soil performs well at low frequencies and forms the basis for the absorption coefficients in the lower ranges and the plants perform better at high frequencies. Compared to other building materials these absorption coefficients for high frequencies are very good.

4.4.3 Living walls (Delft)In 2011, Roby van Praag researched the absorption of living walls at Delft University of Technology. She performed tests on two living façade systems and several types of plants in pots with different kinds of growing media. (Praag 2011)The two systems that were tested are shown on the left. The first (Zuidkoop) is a wooden system that is a fully closed façade. The second is a system with aluminium containers (Zeger Reyers). Both are meant for indoor usage.

In this research the sound absorption is determined in a reverberation test like the one in the reverberation chamber in Singapore. The test room is displayed on the left. The absorption of the two systems was defined as follows:

system posititon 125 250 500 1k 2k 4kZuidkoop corner 0,22 0,46 0,71 0,78 0,53 0,59

length 0,31 0,58 0,85 0,76 0,66 0,63Zeger Reyers width 0,02 0,11 0,23 0,52 0,41 0,32

length 0,02 0,03 0,2 0,44 0,5 0,39

Figure 4.17: Zuidkoop & Zeger Reyers systems

Figure 4.16: Absorption coefficients

Page 48: Living Facades

46

The wooden system performs a lot better than the aluminium, because it forms a closed wall, and the aluminium system has opening between the containers. The report concludes that the exposure of growing media forms a large influence on the absorption performance of the systems.

Another interesting outcome from this report of the tests on growing media is the sound absorption of natural soil which appears to be performing a lot better at the 500 Hz band than other growing media. In general the tested growing media (soil, hydro grain, seramis) are concluded to be good sound absorbers.

4.4.4 ComparisonTests with indoor plants show that all plants perform better in the higher frequency bands. Results fluctuate between plant types. The measurements in Singapore show that the soil has a big influence, which is also shown in the results in Delft. The systems in Singapore show the best results in the 4k Hz band, the systems in Delft in the 1k Hz band. Compared to a glass façade, the absorption of plants makes a large difference. Below the acoustic performance of a single pane of glass is displayed:

125 250 500 1k 2k 4kAbsorption coefficient 0,10 0,04 0,03 0,02 0,02 0,02

(DGMR 2005)

This table shows that the absorption coefficient of a single pane of glass is a lot lower than the performance of a living façade. Where the living façade performs best in the higher bands with up to 80% absorption, the glass performs best in the 125Hz band with only 10% absorption and less in the higher bands. The living façade thus performs a lot better on sound absorption.

If we look at sound insulation, the results in Singapore show only 5dB extra insertion loss through the wall, if a living façade is added to the concrete slab. If we look at performance of a single pane of glass or the effect of extra insulation on the façade, we can compare this improvement of maximum 5dB around the 700Hz band:

Figure 4.18: Test mounting Delft

Page 49: Living Facades

47

R- totaal 125 250 500 1000 2000Single glass 4 mm 27 19 22 26 30 32Single glas 8 mm 29 23 26 30 32 28Double glass 4-6-4 mm 26 22 23 23 32 35Double glass 4-100-4 mm 36 24 32 40 48 50Gas filled double glass 5-9-8 mm 30 24 22 32 39 39

(Kennisbank Bouwfysica 2009)

The difference between single glass of 4 or 8mm in the 500 band is only 4dB and in the 1000 Hz band 2dB. If gas-filled double glass is applied the difference is enlarged to 6dB and 9dB. For this little difference a lot of extra material and expense are made. However, the results from the experiment in Singapore cannot be understood understood totally with the given results.

Another distinction should be made on these conclusions in sense of the openness of the wall. The sound insulation of the vegetation depends on the density of the vegetation. More vegetation means more sound insulation and inverse. For sound insulation the correlation between these two parameters is logarithmic. (see picture on the right) Therefore a little amount of openings in a material can cause large insulation losses. This effect can cause large fluctuations in the insulation of vegetation. For glass panes, which are fully closed, this effect of openings does not apply.

4.4.5 ConclusionsThe living façade can absorb, reflect and diffract sound. The absorption coefficient of a living façade system could be as high as 0,85, as is shown in the research in Delft. The growing medium of the system has a big influence on the performance of the living wall. Soil seems to perform very well around the 500 Hz band, other growing media seem to perform best around 700 Hz.

On the urban level, the absorption coefficient can make a large difference compared to the hard city materials. Compared to glass the plants have a very good overall performance. On the building scale, the plants can add an average of 5dB around 700 Hz to the sound isoltation of the façade. This is a great improvement compared to the differences that can be made by the choice of glass. Results used are not complete enough to fully understand all the effects of the façade, but do help to understand that the plants have a large influence on the acoustic performance of the façade. It is also expected that these amounts of insulation are heavily influenced by vegetation density.

Figure 4.19: Logarithmic scale

Page 50: Living Facades

48

4.5. BiodiversityWorldwide, around 17.000 of the 48.000 assessed species are threatened with extinction. (IUCN 2009) This is a strong indication that biodiversity worldwide should get serious attention. Overall, it can be seen that there is also a decrease of species in cities. However, there is a group of species that grows due to adaption to the city environment. Also, alien species immigrate to cities from all over the world and fl ourish. This leads to new ecotypes in cities that contain new subspecies. (Wittig 2004) The creation of more green surfaces will help this process. In this way, a living façade can contribute to the biodiversity of our cities.

Biodiversity is important to a city. “Ecosystems provide three kinds of services to the city: provisioning, regulating and enriching.” (UNEP & UN Habitat 2005) Provision that biodiversity off ers, includes aspects such as food and clean water (see chapter 4.1 & 4.7); regulating functions of city ecosystems include water cycles and climate stabilization (see chapter 4.7, 4.8 & 5); enriching functions include aesthetic and spiritual terms (see chapter 4.6)

In terms of provision the living façade creates a possibility for local plants to grow. Thus, the façade can enforce local ecology. The NYFA (New York Flora Association) has compiled a list that contains all fl ora in the state of New York. Distinction is made be tween native and imported plants. According to this source, some 482 diff erent species of fl ora are known to grow in the state of New York. (New York Flora Atlas sd) These can be given the opportunity to grow in the ever growing cities by implementing them on living walls.

Besides plants, the façade might be able to house animals as well. In Manhattan there is no wildlife, except for some bird species. According to the Federation of New York State Bird Clubs there are now as many as 455 species representing 19 orders and 62 families of birds in the entire State of New York. In Manhattan there are less than sixteen species. (New York State Biodiversity Project 2001) Studies show that this biodiversity is infl uenced by changes to green areas and green structures. For example, the density of house sparrows in residential areas is roughly three times greater in situations where gardens are present. “The model used predicts a drastic fall in the abundance of house sparrows if even a small area of private gardens becomes one of uninterrupted building.” (Wener en Zahner 2009)

Figure 4.20: Bird Richness

Page 51: Living Facades

49

Overall, two things are important to support wildlife. First is providing food sources, either directly in the form of berries, nectar, nuts or seeds or indirectly as a result of encouraging invertebrates.

The second is to provide shelter , which is necessary for wildlife to feed, hide, mate and breed. Usually it is native species that are of most value, because they have evolved together with the animals that depend on them. Shrubs with flowers can provide nectar for butterflies; climbing plants can provide nesting possibilities for wrens, blackbirds, song thrushes and house sparrow; Particular species such as cotoneaster, ivy, climbing roses and some honeysuckles produce berries enjoyed by birds as cold weather food. (Johnston en Newton 2004)

The provision of these plants and animal species by the living façade is important to the stabilization of the urban eco-system itself. “Ecosystems are important for regulating pests and vector borne diseases that attack plants, animals and people. Ecosystems regulate pests and diseases through the activities of predators and parasites. Birds, bats, flies, wasps, frogs and fungi all act as natural controls.” (TEEB 2010) Protection against these pests and diseases is a large issue in Manhattan. The whole population has problems with so-called ‘bedbugs’ nowadays. “Tiny blood-sucking bedbugs have become an epidemic in New York City. The little pests have invaded even the cleanest and most expensive apartments in neighbourhoods around New York.” (Skillings 2010) NYC’s Community Health Survey (2009) found 6.7% of adults reported bed bugs in their homes in the past 12 months. A regulating city eco-system would thus be very welcome for this problem.

4.5.1 ConclusionBiodiversity in city ecology is important, because of its provisioning, regulating and enriching functions. For the city ecology itself, the regulation of pests and diseases is an important function. A healthy city environment can solve problems such as the current bed-bug nuisance. The living façade can house plants and thereby also provide food and shelter for animals. In this way, the façade contributes to a rich ecology.

Figure 4.21: Food source

Figure 4.22: Shelter

Page 52: Living Facades

50

4.6. Social and psychological improvementsThe plants also have a direct impact on people: people seem to feel better in a green environment. This theory is called biophilia and suggests that people feel better next to all that is alive and vital. It is a feeling of a bond between humans and other live forms that comes from “the connections that human beings subconsciously seek with the rest of life.” (Wilson 1984)

Scientifi c studies show the eff ects that plants have on human health. For instance, it is established that visiting a botanical garden lowers blood pressure and reduces heart rate. (Owen 1994) Other studies show that the presence of vegetation will speed recovery from stress. (Ulrich 1991) Also, research shows that in an offi ce space the score sum of symptoms of discomfort was 23% lower during the period when subjects had plants in their offi ces compared to the control period. (Fjeld 1998) Houses can even gain up to six percent extra value due to a good tree cover in the surroundings. (Morales 1980)

A part of the bond that is named in the Biophilia hypothesis could be explained by the fact that our eyes are more sensitive to green light than to other colours. The retina of the eye consists of cones and rods: the rod cells function at low light intensities, as in night situations; the cone cells are less sensitive and used in day situations and allow us to perceive the wavelength of light passing our eye. There are three types of cone cells, each with a sensitivity peak at a diff erent light wavelength. According to this sensitivity, we can determine the colour of the light. (Cyckowski en Grobstein 2009) If we combine the sensitivity of the three types of cones, a peak occurs at 555 nanometres: a yellowish green colour. (Robinson 1984) This means we react more to the colour green than to other colours. Below two diagrams are shown: the fi rst shows the sensitivity of the three types of cones. The second shows the total sensitivity of the three cones combined.

4.6.1 Conclusion Studies show that plants have a positive eff ect on humans. The hypothesis that people feel better in a green environment is called the Biophilia hypothesis. This eff ect may be explained by our sensitivity to the colour green. There is, however, not enough knowledge on this topic to quantify an amount of plants for the façade.

Figure 4.23: Sensitivity per cone Figure 4.24: Combined sensitivity

Page 53: Living Facades

51

4.7. WaterLiving walls contribute to the water cycle by creating the possibility of evaporation. This is important, because, on a global scale, evaporation of water is the largest and most important component for the conversion of solar radiation.

It is also the largest hydrological component together with precipitation; only water that evaporates causes rainfall. Attention for these cycles is necessary, because of the major interests that are involved. According to the United Nations, 50 million people are at risk of displacement due to desertification over the next ten years and two billion people are potential victims of the creeping effect in the future. (United Nations University 2007) In this chapter we will discuss these effects of the living façade on the water cycle.

4.7.1 The water cycleEvaporation creates a large and a small water cycle of condensation and precipitation. (Schmidt 2006) We will explain here what these cycles are and what the effects of water in these cycles are, to understand their importance.

There are around 1400 million cubic kilometres of water on this earth , which we can divide in four environments: ‘in the oceans’, ‘on land’, ‘in the atmosphere’ and ‘in the biota’. (Kravcík, et al. 2007)

■ The oceans cover 70.8% of the surface of the earth and contain 97.25% of all water. Their temperature is a key to the regulation of temperatures on the planet.

■ Water on land would be mostly associated with rivers (0.0001% of all water volume) and lakes (0.01% of all water volume), but a bigger part is formed by water in solid state such as glaciers or snow that contains 2.05% of volume of all water and up to 70% of the reserves of fresh water. Apart from this solid water, groundwater and soil moisture represent 0.685% of all water, exceed-ing the volume of rivers and lakes.

■ The volume of water in the atmosphere is around 0.001% and has a key role in local thermoregulation, fluctuating in concentration from 1-4% (CO2=0.0383%).

■ Water in living organisms forms 0.00004% of the volume of all water on earth. On land vegetation has an important role in maintaining thermal stabil-ity by evaporation.

Figure 4.25: Water cycle

Page 54: Living Facades

52

Reservoir V (mln. km3) Percentage Oceans and seas 1370 97.25 Icebergs and glaciers 29 2.05 Groundwater 9.5 0.68 Lakes 0.125 0.01 Soil moisture 0.065 0.005 Atmosphere 0.013 0.001 Rivers 0.0017 0.0001 Biosphere 0.0006 0.00004 Total global reservoir of water 1408.7053 100

Solar radiation falling on the earth causes water from all environments to evaporate and the evaporation of each water molecule cools the surface of the earth. The water vapour rises into the atmosphere where it condenses under the influence of cold air and thus releases thermal energy. Also, the water vapour in the form of clouds shields solar radiation. In this repeating process, water works as a cooling mechanism for our planet. In this process, we can see a large cycle in which 86% of vapour evaporates from the seas and 14% from land while 26% of all the precipitation falls over land. In the small cycle, water moves in a closed circulation over the same terrestrial environment , which forms 57%of all precipitation over land. This means we should ensure evaporation over land, if we want to have stable precipitation.

In this process, plants fulfil the role of valves that protect the ground from overheating and drying out and that optimize the amount of evaporation by transpiration by which they can regulate the temperature of the air. If there is disruption of vegetation by, for example, deforestation, agricultural activities or urbanization, solar energy is turned into heat and temperature differences increase.

Figure 4.26: Large and small cycle

Page 55: Living Facades

53

4.7.2 Importance of the water cycleThe sun sends 180.000 TW of energy to Earth every year. In comparison, humanity only uses 14 TW for its economy. Of this energy, about 30% is reflected back into space, 47% becomes thermal radiation and 23% used in the water cycle for evaporation. The maximum amount of radiation reaching the surface of the earth, can be as much as 3.000 KWh/m2, but in our geographical surroundings it reaches an average value of 1.100 KWh/m2. The exact amount of energy depends on the weather and the time of year. (NASA, Surface meteorology and Solar Energy 2010) The fate of this radiation depends on the amount of water in an ecosystem , which distributes the radiation over sensible heat (an increase of temperature), and latent heat (due to the vaporization

of water). The specific latent heat of water at a temperature of 25°C and under normal pressure is 2.243,7 KJ/kg, which is the amount of energy used to evaporate a litre of water without increasing the temperature. If water is not present on land, solar radiation is directly turned into sensible heat. In dehydrated areas about 60% of solar radiation is turned into sensible heat, whereas, in areas saturated with water, about 80% of solar radiation is turned into latent heat.

4.7.3 RainwaterIn addition to the latent heat effect, the infiltration of water in living façades leads to a more equal burdening of the city drainage system. The paved surfaces in the city lead to rapid run-off of rainwater. Cities normally drain this rainwater away from the territory as quickly as possible, leading to dehydration of a piece of land. This can lead to a higher risk of flooding in other areas or in sewage systems, but also to a lack of latent heat in the urban area. This contributes to the Urban Heat Island Effect as described in the next paragraph.

“Average green roofs absorb 75% of precipitation that falls on them so that immediate discharge is reduced to 25% of normal levels”. (Newton 2004) This means that sewers are better able to cope with run-off from the streets and other hard surfaces and that the risk of flooding is considerably reduced.” (Johnston en Newton 2004) In this way, these façades contribute to the small water cycle by keeping water in the city. This will prevent water run-off to the oceans and thereby scarcity of water on land in many parts of the world. This could be a future horror as predicted by the UN. (UNDP 2006)

4.7.4 ConclusionsFor the conservation of the water cycles, as many plants as possible are desirable on a site. This especially holds true for an overheated city like New York. A façade that can capture more water would be preferable. However, most important is that the plants are present and provide evaporation. To enlarge the effect on the heating of the city, the greenery on the site should be maximized.

Figure 4.27: Global radiation

Page 56: Living Facades

54

4.8. Heat island effectPlants are shown to have an effect on The Urban Heat Island Effect (IHIE). This effect is the result of two main properties of urban areas. First, buildings, roads and paved surfaces store heat during the day, which is then released slowly over the evening due to the thermal properties of the surface materials and the building geometry, which trap the heat stored during the day. This problem is connected to the climatic principles described in paragraph 4.7.1. The second contributing factor to the UHIE is due to the artificial heat released into the urban atmosphere by combustive processes from vehicles, industrial activity and the heat that escapes from commercial and domestic air conditioning. (Urban Heat Islands and Climate Change 2006) It is measured that during the summer months the daily minimum temperature in the city is on average 4°C warmer than surrounding suburban and rural areas. (New York City regional heat island initiative 2006)

4.8.1 Absorption of heatThe first aspect, the absorption of solar radiation and release of heat, relies on the properties of the materials used in the city, such as asphalt, brick and concrete and various kinds of roof materials. These often stony and dark materials absorb most of the solar radiation resulting in an increase of sensible heat in the city. These surfaces can cause cities to be averagely 5°C warmer than a meadow at noon on a summer day.

It is obvious that this is an unwanted effect our buildings and infrastructure have on our living environment. Solutions to this problem can be found in both reflecting solar radiation in a way that the heat is turned away from the city, and in creating a way to turn the solar radiation into latent heat. Surfaces can reflect heat by their colour. Most roofs in cities are now coated with black EPDM, which absorbs all solar radiation. If these surfaces are changed from black to white, a lot more solar energy is reflected back into space and thereby the surroundings get cooler. The next images show a relation between the temperature and vegetation in Manhattan. In Manhattan, about 64% of the surfaces are dark and absorb solar radiation. (NASA, making of Urban heat island 2009)

Figure 4.28: Heat island

Figure 4.29: Temperature Figure 4.30: Vegetation

Page 57: Living Facades

55

The temperature differences of New York compared to its surroundings is 4°C on average. (New York City regional heat island initiative 2006) As we can see in the image on the previous page, green spaces have a large effect on the cooling of the city, as described in the previous chapter. This is caused by all the water the plants in these green spaces evaporate. “For each gram of evaporated water plants absorb 633 calories”. (VEJA 2009) This is as much as 2648,5 kJ/kg, a little bit more than the latent heat of water. Living walls can improve the city by offering more surfaces that evaporate water. Also, unlike a stony surface, the living wall does not store heat, whereby it does not contribute to the Heat Island Effect.

A model of the climate in New York (MM5) made by Gaffin, shows weighted average near-surface air temperature reductions for selected mitigation scenarios. These scenarios are averaged over all times of the day and at 3 PM, and assume implementation in 100% of the available area of Manhattan. (New York City regional heat island initiative 2006)

In this table we can see again that especially in Manhattan, roofs and surfaces have a large influence compared to the other areas. The biggest advantage can be gained by a combination of urban forestry and light roofs. By implementing urban forestry and light roofs, we reverse the disappearance of vegetation from the city and reintroduce the evaporation process of these plants, while the dark surfaces that absorb solar radiation are made reflective and thereby cooler.

According to Gaffin, about 17% of Manhattans surface can be planted with trees. 14% of all the dark surfaces is formed by roofs. Other surfaces are roads, pavements and of course: façades. Implementation of living façades can help eliminate one of these three remaining categories. Living walls deal with this effect by the transpiration of the plants, in which solar radiation is turned into latent heat, which prevents the rising of sensible heat.

Page 58: Living Facades

56

4.8.2 Addition of heatAnother part of the problem is the energy use and heat from machines, installations, cars and industry. In Manhattan, a big part of this is heat released by air conditioning. In the image on the next page the energy use in New York is shown, which suddenly rises as temperatures get higher than 18°C (61°F). This increase in energy use is mainly caused by the demand in air cooling. (New York City regional heat island initiative 2006) The problem is paradoxical. On the one hand the heat in the city leads to increasing energy demand for air-conditioning; on the other hand the air-conditioning heats the city even more.

In the graph we can see the increase in energy demand of about 100 to 150 GWh caused by a temperature increase of 10 degrees. The air conditioning machines deliver this energy back to the city in the form of extra heat. This is a very unwanted effect, in which a lot of energy is wasted and the actual problem only becomes worse.

4.8.3 ConclusionBy maximizing the amount of planting on the site, the effect on the Urban Heat Island Effect can also be maximized. Preferably, the materials in the applied living façade have as less warmth absorbing surface exposed to solar radiation as possible. If there are parts of the façade that are not covered by greenery, they should have a light colour. By upholding this aspect the energy use of the entire city can be lowered in the future.

Figure 4.31: Energy demand

Page 59: Living Facades

57

5. heatAs we have seen in the previous chapter plants have an influence on climate and temperature by their capability of evaporation. Just as in the case of the Urban Heat Island Effect (on city level) the plant’s capabilities can be used on a building scale as well. In this chapter a focus on the thermal influence on a building scale is given. The aim of the thermal calculations is to make an equation by which the amount of living façade, plants and glass can be determined for the façade of the building , which can give grip on the design project and lead to a better façade.

5.1. Thermal influenceThe plants on the living façade can improve thermal insulation for the building for a number of reasons. In this paragraph a description of the important factors for these aspects will be given to provide a basic understanding which can help to make calculations with heat.

There are several ways in which the plants improve thermal insulation for the building:

■ Air in-between the leaves insulates ■ Wind is curbed ■ Wind speed around the building lowers ■ Leaves provide shades ■ Leaves provide cooling by water evaporation

An important factor for the magnitude of the thermal impact is the kind of plant that grows on the façade of the building. Each kind of plant has its own properties , which can make quite a difference in the thermal behaviour of the façade. In the various kinds of vegetation, plants can be chosen on the basis of several requirements , which will be explained below: (Lesiuk 2000)

■ Deciduous vs. Evergreen ■ Complete vs. incomplete canopies ■ Leaf angle distribution: vertically hanging leaves through to horizontal leaves ■ Transpiration capabilities: high transpiring plants vs. low transpiring plants.

The deciduous plants lose their leaves in winter and can thereby be helpful in getting more sunlight and energy into the building in winter, while they can shade the building in summer. With their leaves, the plants also lose their thermal capabilities for insulating the building. In places where there is a lot of wind, this might be a problem, because the façade will thus get less insulated in winter, when most insulation is needed. Deciduous plants can therefore be used best in cases where sunlight is the most important factor to apply the plants.The evergreen plants keep their leaves in all seasons and are green the whole year, which explains this term. These plants therefore keep their influence on the thermal and daylight entry properties of the building in winter. This is especially useful for the limitation of convection by wind , which lowers the heat loss in a winter situation. The leaves create extra insulating capabilities for the building façade, by locking an extra layer of air around the building , which reduces the heat flow through the façade.

Page 60: Living Facades

58

Deciduous plants can be stimulated by keeping the soil or growing medium moist, since evergreen species grow better on drier grounds than deciduous species. (Atwell, Kriedemann en Turnbull 1999)

Strictly speaking, the canopy of a plant is the part of the plant that grows aboveground. In this list of requirements for plants, the canopy of a plant refers to the outer layer of leaves of a plant that forms a plane over the living façade. Plants that have complete canopies form a closed plane while plants that have incomplete canopies leave gaps in the vegetation , which causes the rear structure to be visible and exposed to sun and wind. If plants with a full canopy are planted on the living wall, the sunlight will be shaded more and the wind will be blocked better. The canopy of a plant is not only dependent on the amount of leaves but also on the leaf shape, disposition and margin. Some plants have leaves with a shape or margin that cannot easily form a closed layer; other plants have a disposition of leaves that is too spread to make a closed layer. (see also appendix B for leaf characteristics)A way to express the amount of leaves and their coverage is the Leaf Area Index (LAI). This is the ratio of the total upper leaf surface of vegetation divided by the surface area on which the vegetation grows. Bare ground has a LAI of 0 and dense forest a LAI of 6. A high LAI does not strictly mean that there is a more closed canopy. A tall plants with the same LAI as a smaller plant forms a less closed layer. However, for the average plant the canopy will be more closed if the LAI is higher. In the picture below the LAI of three plants is shown; the growing area is defined by the dotted rectangle.

The leaf angle distribution (LAD) of a plant is a mathematical description of the angular orientation of its leaves on the basis of the zenith and azimuth. For example, grasses have an erectophile (vertical) LAD and oaks have a planophile (horizontal) LAD. Some plants have a more erectophile LAD at the top and a more planophile LAD at the bottom , which might be caused by the plant’s strategy not to shade itself. The leaf angle distribution affects the completeness of the canopy and thereby the shading of sunlight and the blocking of wind.Plants, growing on a vertical surface, provide better shading if they have a more erectophile LAD; plants on a horizontal surface provide better shading with a planophile LAD (See picture below).

Figure 5.2: Use of LAD

Figure 5.1: LAI

Page 61: Living Facades

59

The transpiration capabilities of plants differ per kind and are also related to the amount of sunlight that shines on the plant. Plants tend to cool themselves by evaporation in order to maintain their internal temperature, which is necessary for the chemical and biological processes in the leaves. The plants respond to the air temperature, as well as to the heat of the sunlight shining on their leaves, and to the heat released in the photosynthesis process. The transpiration rate of the plant determines the amount of cooling. If the transpiration rate is higher than the moisture absorption rate of the roots, the plant runs the risk of wilting. This makes the transpiration capacity also dependent on the humidity of the soil or planting medium. Besides, plants that live in a more moist growing medium are shown to wilt with a higher moisture content. (Moinat 1932) This means that the amount of cooling is limited and an optimum can be found between growing medium moisture and transpiration.

The plants on the living façade have to be chosen on the basis of these four requirements. As shown, the requirements can have various consequences for the warmth of the building. In order to be able to make a choice, the thermal properties have to be determined first. This can lead to conclusions on the requirements for the plants. The only factor that influences the choice for a specific system is the transpiration capability. If the transpiration capabilities should be high, a more moist system would be needed, but this is accompanied by a high risk of wilting. If this risk has to be lowered to prevent the green living façade from turning into a brown living façade, a system should be chosen that is less moist, representing a system with soil that is not irrigated too much. This results in lower transpiration rates.

Figure 5.3: Transpiration

Page 62: Living Facades

60

5.2. Calculations on thermal behaviourNow that the most important factors for thermal behaviour entry are clearer, a calculation can be performed with the properties of the living façade. In this paragraph, the thermal influence will be quantified to express its influence.

5.2.1 ModelIn the report “Modelling the double skin façade with plants” (Stec, Paassen en Maziarz 2004) a model is made of a double skin façade (see picture on the left). In this model a heat flow in a cavity with plants is described. The heat flow passes, from left to right: an outer glass pane, a first half of a cavity, plants (Hedera Helix), a second half of a cavity and an insulated wall. In this report a mathematical model is given that simulates the heat flow through these layers. Eight thermal knots are defined to express the radiation, convection and transmission in the cavity. Radiation from the environment is not considered in this model.

The right part of this model can be used to simulate plants that are on the outside of a glass façade. Such a model can look like the model on the left. Radiation falls on (qsun) and through (αr1) the plants and warms the plants and glass. Part of this heat forms a convection flow (αc2; αc3) through the cavity. The outside temperature influences the model by another convection flow coupled to these two (αc1). A part of the heat of the plant is made into Latent Heat (LH) by the transpiration process. The heat in the glass is transmitted from T1 to T2.

An important difference between this model and the model of Stec is the air flow in the cavity: the wind will pass

through the plants and exchange heat (z1) with the outdoor air (Tout), so the cavity will be heated less than in the Stec model. This influence of the wind is not completely certain though: “In experiments in Germany no air movement was detected in the space behind a 50cm thick growth of ivy.” (Johnston en Newton 2004) This means that there has to be a very thick layer of leaves before wind is eliminated. It is therefore assumed that a wind flow through the leaves does

Figure 5.4: Stec’s calculation model

Figure 5.5: Moderation of Stec’s model

Page 63: Living Facades

61

occur. The thermal knots derived from Stec are useful to indicate the parts of the thermal process. The three convection flows, the radiation flow, the Latent Heat, solar radiation and wind will influence the glass façade that is covered by plants. We will use these factors to investigate the properties of the façade further.

5.2.2 Leaf coefficientsThe total heat flow through the plants in this model is qtotal= qtransmission + qradiation + qconvection [W/m2]. A simple calculation of these heat flows can be made by using standard coefficients for reflection, transmission, convection, absorption and solar energy used (for photosynthesis) for leaves (Krusche, et al. 1982). We use the minimum and maximum coefficients of a single leave to make a minimum model (1) in which most of the solar energy passes the plant to the glass of the building and a maximum model (2) in which most of the energy is reflected, used for photosynthesis, or converted into Latent Heat and the least energy passes to the glass façade behind the plant.

For the calculation qsun= 600W/m2 is used. This represents the amount of solar energy on a typical summer day on a south orientated (vertical) façade. The typical characteristics of HE++ glass are defined as d=23mm (4-15-4); M= 20kg/m2; U=1.62W/m2K; G (passing heat) = 0.60; L (passing light) = 0,75.

The heat flow on the glass of the façade is influenced by the plant via reflection (5-30%), energy used for photosynthesis (5-20%) and absorption by evaporation (20-40%). Model 1 is calculated with the highest coefficients for energy passing the plant and model 2 is calculated with the lowest coefficients for energy passing the plant in order to form the minimum and maximum model of energy that can pass the living façade, which shows the influence of the plant. Both models are expressed in the table below:

Plant min% max% model 1 [W/m2] model2 [W/m2]Reflection 5 30 5 30 25 150Transmission 10 50 40 240 10 60Convection 10 50 30 180 10 60Photosynthesis 5 20 5 30 20 120Latent heat 20 40 20 120 35 210On façade: 100% 420 100% 120

In both of the models, the amount of heat that passes the plant is formed by the sum of the transmission and the convection flows. For model 1 this is 420W/m2 and for model two this is 120W/m2 as shown in this table.

In model 1 about 420W/m2 passes the plant in the most extreme case, without taking into account the heat convection flows directed away from building instead of going to the façade. In reality the value will be closer to 240W/m2, because not all convection energy flows toward the façade. This is even more probable when wind is also taken into account. The convection heat flow with average wind is 19 to 20 W/m2K and with strong wind 100 W/m2K. If wind has an influence on the space behind the plant as was presumed before, the heat flow to the façade will thus be smaller.

Page 64: Living Facades

62

In model 2 there is a maximum amount of passing heat of 120W/m2. This amount will also most likely be closer to 60W/m2 as explained for model 1; this is a reduction in the heat flow from solar radiation of almost 90% compared to a glass façade without plants growing in front of the glass. This is a very high percentage and more likely, the heat flow will be somewhere in between 60 and 400 W/m2; in which the lower limit of 60 W/m2 is a bit unrealistic. Theoretically however, there must be a reduction in the amount of sunlight passing, compared to the normal situation, because a part of the light will always be blocked by a leaf. As we can see in the figure below this is an improvement on the heat load on the glass of the façade, as the plants function as added blinding to the façade.

This effect on heat flow (like blinds against the sun) can also be seen in the results of experiments of Stec with plants and blinds in a double skin façade. The results in temperature are shown in the table below.

We see in this table that the plants and the blinds result in a lower temperature on the wall. This is, of course, because they shade a part of this wall. The plants cool the wall even more than the blinds , which can only be ascribed to the extra energy used in photosynthesis and absorbed in the transpiration process , which turns the heat energy into latent heat.

Figure 5.6: Plants as blinds

Page 65: Living Facades

63

The calculation used above is not very precise, however, not only because typical percentages are used, but also, because these percentages are derived from a single leaf and not a total plant. In case of a total plant we must take into account that a plant has a distinct leaf growth density that affects the canopy of leaves on the living façade. We can take the properties of a specific plant into account by looking at the Leaf Area Index and the Leaf angle distribution of a plant. Both LAI and LAD vary for every plant kind and therefore the thermal behaviour of plants differs a lot. Even the size and age of a plant count in this matter. A plant that is not full-grown will have fewer and smaller leaves. This lowers the LAI and therefore the chance is higher that sunlight can pass the leaves.

The shade of the plant leaves can be generalised in a simple formula that describes the amount of passing sunlight. Of the 600W/m2 solar radiation in the previous calculation, a maximum of 420W/m2 passes a single leaf. This amount is more likely to be lower than the amount of 120W/m2 which model 2 showed. In this report we will estimate the amount of sunlight to decrease to an average of 330 W/m2. This means that 0.55 times the radiation passes the plant. Every next leaf will multiply this amount by another 0.55 part. This means that the relation between the LAI and the amount of passing sunlight can be described as qpassing= q*0,55^LAI. With this relation we can be more specific about the influence of the canopy of a plant on the thermal properties of the façade.

For example, a full-grown plant can have a LAI of 5 or even much higher, depending on the species. In that case, the heat load on the façade will decrease by a power of five , which results in a heat flow of qpassing= q*0,55^5= 30 W/m2 reaching the façade. This indicates the influence of plant choice and lifetime on the behaviour of the façade.

If the light just passes the plants, the two models based on behaviour of leaves in sunlight do not apply and the glass of the façade gets a full 600W/m2 solar radiation. This will definitely increase the heat load on the building. To be more precise in calculations, it would be smart to calculate with parts that are not covered by plants and parts that are covered by plants with a given Leaf Area Index.

5.2.3 Ambient temperature of the leavesLooking at the research of Wong on the thermal influence of living walls there is a temperature influence of the wall that affects all surrounding air. The ambient temperature around the living wall can be about 3°C lower in summer, even at a distance of 30cm from the living façade. (Wong, Tan, et al. 2009) This cooling effect from the evaporation of the plants influences the temperature difference between in- an outside and thereby influences the heat flows through the façade. If, for example, the in- and outside temperatures are 25°C, there is no convection heat flow through the façade, because there is no temperature difference between in- and outside. The plants cause the ambient temperature around the living façade to be 22°C by their evaporation. This temperature difference will start a convection heat flow from the interior of the building to the cooler plants. Now the building cools down compared to the ‘normal’ situation.

Page 66: Living Facades

64

On a typical summer day with a solar radiation of qsun= 600W/m2 on the south orientated façade, the convection heat flow through the glass will be q=U* ΔT= 1.62W/m2K*3°C = 4.86W/m2; a cooling capacity of almost 5W per square meter of living façade.

This also means that the convection flows from the leaves, as defined in models 1 & 2 in the previous paragraph, will flow away from the façade and that the total heat flow from the sun to the façade is limited to 60- 240W/m2, which is only the light transmitted trough the leaves. Of course this is only the case if the LAI of the plants in front of the glass is at least 1. Also, if the outer temperature is higher than the inner temperature, the convection heat flow has to be calculated with q=U* ΔT= 1.67 [W/m2] * (Tout-3-Tin) in order to determine the heat flow.

5.2.4 Winter situationIn winter the plants can contribute to the building by means of insulating the façade from the cold outside air and by decreasing the influence of the wind. “In winter, evergreen species offer a degree of insulation by trapping a layer of air against the façade and reducing convectional heat loss. An insulating effect of up to 30% has been recorded, although such a high percentage is only likely when temperatures fall close to freezing” (Johnston en Newton 2004).

Again, for this effect the canopy has an enormous influence on the real insulation value, since it defines the capability of the plant to enclose a layer of air between itself and the building. However, these results count especially for old buildings with a lack of thermal insulation. The insulating effects are not expected to greatly influence the façade as defined in the preliminary design, because the plants will not grow dense enough, especially not in front of the glass. Also, the insulation from a new well-insulated façade is expected to be much higher than the insulation from the air between the plants. Therefore the capacities of insulation by trapping air will not be discussed further.

Figure 5.8: Heat flow from glass to plant

Page 67: Living Facades

65

5.3. Interior climateIn this paragraph a focus on the interior climate will be given to define the amount of solar energy needed or unwanted. This can help to make a statement on the desired shading and insulating properties of the façade . In this way, the proportion and density of the greenery on the façade can be determined with the knowledge on heat reduction from the previous paragraph. First all important factors of the thermal calculation will be explained. Successively these are defined as the comfort temperature of the indoor climate, the convection flows in summer and winter, solar radiation, internal heat loads, thermal mass, ventilation, influence of greenery and the warming of the air. Together these factor will be used in an Excel model that will be explained in the last part of this paragraph.

5.3.1 Comfort temperatureIn order to be able to define the amount of greenery on the building, the most sustainable solution for the interior climate of the building is defined. This would be the situation in which the comfort temperature in the building can be maintained with heating by gaining solar energy, cooling with ventilation and without adding any other energy source.

The standard temperature for all United Nations buildings in Manhattan is set at 21°C. In terms of comfort, this temperature can be higher in summer and lower in winter. In the graphs below the comfort temperature is placed as a graph of the outdoor temperature:

Figure 5.9: Comfort temperature without openable windows

Page 68: Living Facades

66

In buildings with windows that can be opened, the indoor temperature can be higher in summer than in a building without such windows. For the design for the United Nations it will be assumed that the windows cannot be opened.

Most influential to the interior temperature are the hottest and the coldest month of the year, which will be normative for the thermal calculations. In New York, January is the coldest month with a daily mean temperature of 0.1°C, an average daily high of 3.3°C and an average daily low of -3.2°C; July is the hottest month with a daily mean of 24.7°C , an average daily high of 29°C and an average daily low of 20,4°C.

A high ambition for the comfort level will be set to meet the American expectations of the building and in view of the American habits of climate control and air-conditioning. Therefore, the acceptance level of the indoor temperature will have to be higher than 90% to give comfort to most of its users. According to the previous graphs, the comfort temperatures for the extreme summer and winter conditions will be at least 20.5°C and at the most 23°C in January; and at least 22°C and at the most 25°C in July. This indicates that, in terms of comfort, the temperature may differ from the 21°C target that is set by the UN. This variation can help to allow more solar radiation into the building and thus make a more open façade.

5.3.2 Heat transfer through the façadeThe first important aspect of the indoor temperature is the heat transfer through the façade. This heat flow is caused by the temperature difference between the outdoor temperature and the indoor temperature, which influences the amount of heat in the building and thereby the indoor temperature.

For calculations of the heat flow through a façade, the heat transfer coefficient (U) of the façade is determinative, together with the temperature difference (ΔT ) between indoor and outdoor climate according to the formula q=U*ΔT. In this formula U is expressed

Figure 5.10: Comfort temperature with openable windows

Page 69: Living Facades

67

For the glass façade an U value of 1.62 W/m2K has been defined (see paragraph 5.2.2). The outdoor temperatures in New York were also given previously (in paragraph 3.3). The total amount of façade can be determined with the dimensions of the 5 building variants. These are given on the right (for calculation see appendix C). Note that the façade surface of shape B is 150% of the façade of building D. To show the influence of the convection flow through the façade, the flows for summer and winter situations will be calculated. Based on an indoor temperature of 21°C and the average daily high temperatures that occur in the daytime in January, the temperature difference between the exterior and the interior temperature in winter will be ΔT=Tout-Tin=3.3-21=-17.7°C. The heat flow through the glass will then be q=U* ΔT =1.62*-17.7= -28.67W/m2, which is a heat loss. In July, the temperature difference ΔT= Tout-Tin =29-21= 8°C. This means the heat flow will be directed from the outside in, through the glass, and the heat flow q=U* ΔT = 1.62*8= 12.96W/m2, which means the building warms. With these flows and the façade surfaces (see appendix C) the amount of energy for an hour can be calculated in MJ: (in summer situation the flow is directed into the building, in winter it is going out of the building)

Summer WinterSurface (m2) Heat flow (W/m2) Heat (MJ) Heat flow (W/m2) Heat (MJ)

A: 11.648 12,96 543 28,67 1202B: 14.780 12,96 690 28,67 1525C: 11.080 12,96 517 28,67 1144D: 9.817,5 12,96 458 28,67 1013E: 10.392,9 12,96 485 28,67 1073

Figure 5.11: Building shapes

in Watts per square meter degree Kelvin (W/m2K) and ΔT in degrees (°C =°K) which results in a value q in Watts (W/m2). The value ΔT is defined as ΔT=Tout-Tin, which means that a positive flow is directed into the building and a negative flow is directed out of the building.

The total amount of energy can be determined by multiplying the heat flow (q) by the amount of façade surface (A) according to Q=q*A, which results in an amount of heat (Q) in Watts (W). In the Excel model this amount of heat per hour can be converted to Joule, on the understanding that 1W=1J/s. This means that an amount Q[W]*t[s]=Q[J] or 3.600 seconds * [J/s] = 3.6[KJ] energy flows into the building in one hour.

Façade (m2)building A: 11.648building B: 14.780building C: 11.080building D: 9.817,5building E: 10.392,9

Page 70: Living Facades

68

We can see that in summer, the amount of energy that enters the building as a heat transfer is about a hundred times smaller than the amount of energy that flows out of the building in winter.

This situation is only true at the beginning of our calculations, though. Because of the heat transfer the indoor temperature Tin will rise in summer and fall in winter, causing ΔT= Tout-Tin to become smaller. In order to be able to (statically) calculate the situation of the building without ignoring this effect, the situation will be calculated per hour.

5.3.3 Solar radiationAnother large influence on the building’s indoor temperature is the amount

of solar radiation that falls on the façade. Especially in summer, this radiation can cause the building to heat up extremely. This should be prevented, particular in light of the amounts of energy used for airco systems in Manhattan and the share that this energy has in the Urban Heat Island Effect (as described in paragraph 4.9.2).

For the calculation of the solar energy that falls on the building, the solar radiation [W/m2] in normal direction will be used. Because a model with intervals of an hour is made, the solar radiation will also have to be defined per hour. For that reason the data available for the Netherlands will be projected on Manhattan. The values of 15th December with the least radiation and of 15th June with the most radiation are given in the table below: (Van der Linden 2005)

Solar radiation

5:00

6:00

7:00

8:00

9:00

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

Summer (W/m2) 129 327 624 732 798 838 862 874 876 867 848 813 758 665 506 239Winter (W/m2) 10 324 507 587 597 544 401 117

Page 71: Living Facades

69

The amount of solar energy that falls on a façade surface is not only dependent on the solar radiation but also on the direction of that façade in comparison to the sun. A square meter façade that is directed in the normal plane of the radiation, catches more solar energy than a square meter of façade that makes an angle of 45° with this radiation. To define this direction, the place of the sun has to be defined. This position can be described with the azimuth (A) and the elevation (h). The azimuth describes the position of the sun on the horizontal plane as an angle measuring from the North direction. The elevation describes the angle between the direction of the solar rays and the horizontal plane. With these two angles, the position of the sun in the sky can be described from a certain point.

To make variations on the building volume easier, the calculation will use sunlight that only comes from the south. In this way, the orientation of the sun only depends on the elevation and the radiation only falls on the south façade and roof of the building. The elevations through the day on 15th December and 15th January are given in the table below: (US naval observatory 2011)

Solar elevation

5:00

6:00

7:00

8:00

9:00

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

Summer 5,3 15,7 26,8 38,1 49,3 60,1 69,0 72,6 68,0 58,8 47,9 36,6 25,3 14,3 4,0 0,0Winter 6,7 14,8 21,1 25,0 26,0 24,0 19,3 12,4 4,0

Figure 5.13: Postition of the sun

Figure 5.12: Direction of the facade

Page 72: Living Facades

70

With the amounts of radiation (q) in normal direction and the elevation (h) of the radiation, the quantity of solar radiation on surfaces with a different angle can be determined according to the rules of trigonometry. For a vertical surface the radiation V perpendicular on this plane is V=cosα*q. For a horizontal plane the radiation H perpendicular to this plane is H=sinα*q. (see also the picture on the left)

The radiation A on the angular façade of the trapezium with an angle α can be derived in the same way. The total sum of arches on the horizontal plane is 180°=h+β+α. The angle β between the elevation and the angular surface can therefore be defined as β= 180-h-α. The radiation on the angular surface can then be calculated with A=sinβ *q =sin(180-h-α)*q according to trigonometry.

Figure 5.15: Radiation on trapezium

Figure 5.14: Vertical and horizontal radiation

Page 73: Living Facades

71

For an arched façade, the amount of solar energy is determined by finding the section of the volume on the normal plain of the solar radiation (see picture on the right). This section S is built up out of two parts: S1 &S2. The length S2 of the section equals the radius r. The lengthS1 is perpendicular to the solar radiation , which gives us a triangle with a right angle of which one corner is known as the elevation of the sun. Through trigonometry S1 is defined as S1=(r*sin h ). The surface of the section is then defined as S=((r*sin h)+r)*depth.

Now the radiation on each of the building shapes can be determined for 13:00 hours in summer and winter. For that purpose the radiation on the horizontal surfaces qH, the vertical surfaces qV, the angular surfaces with α=63,4 and the section plane through the arched volume are calculated first:

h qnormal qH qV β qA SSummer 68,0 876 812,2 328,2 -41,4 656,7 4818,0Winter 24,0 597 242,8 545,4 2,6 596,4 3516,8

With these relative radiations and the areas of the façade surfaces that are faced south or are positioned in horizontal direction (the roofs), the total amount of heat that the façade is exposed to, can be calculated (in Watt). In the table below the surfaces [A] of the volumes are combined with the relative radiations [q] to get the total amount of solar heat [Q] in Watt according to Q=q*A.

solar radiation Plane A B C D E Horizontal 3200 m2 1.800 m2 5.500 m2 x 2.250 m2

812,2 Summer 2,6 MW 1,5 MW 4,5 MW 1,8 MW242,8 Winter 0,8 MW 0,4 MW 1,3 MW 0,5 MW Vertical 3200 m2 5.500 m2 1.800 m2 x x328,2 Summer 1,1 MW 1,8 MW 0,6 MW 545,4 Winter 1,7 MW 3,0 MW 1,0 MW Angular x x x x 3.075 m2

656,7 Summer 2,0 MW596,4 Winter 1,8 MWTotal Summer 3,7 MW 3,3 MW 5,1 MW 4,2 MW 3,8 MW Winter 2,5 MW 3,4 MW 2,3 MW 2,1 MW 2,3 MW

Figure 5.16: Building shapes

Page 74: Living Facades

72

In summer, shape C is exposed to most heat with 5.06 GW and shape B is exposed to least heat with 3.27 GW. In winter, shape B is exposed to most heat with 3.44 GW and shape D is exposed to least with 2.10 GW of heat. The ideal building form for solar gain would thus be shape B, the vertical tower, which does not gain much energy in summer and does gain a lot of energy in winter.

Not all energy that falls on the building actually enters the building. The amount of energy admitted is lower than the amount that falls on the façade. For the glass parts only 60% of the solar energy is transmitted (as defined in paragraph 5.2.2)

5.3.4 Internal loadsThe sun does not form the only heat load on the building. The users and their electric equipment (mainly computers) in the interior also form a heat load. For each person working in the UN Environmental Headquarters an extra heat load of 80W per person working there is added. Per person an extra amount of 120W for every computer is added. All closed or dark spaces need lighting of 10W/m2. (Erdsieck en Herpen 2005)

There are 600 people working in the UN Environmental Council. This also adds about 600 computers to the interior. The amount of closed functional spaces that need lighting is about 4.000m2. This results in the following extra heat load:

Heat Amount Total People 80 W 600 persons 48.000 WComputers 120 W 600 computers 72.000 WLighting 10 W/m2 4000 m2 40.000 WTotal 160.000 W

5.3.5 Influence of building massThe building mass can be most influential in delaying the heating of the building. It forms a buffer that is of importance in view of the high amount of solar energy that falls on the building. Its function consists of the property that walls or floors in the building can warm up and thus function as thermal mass. Especially walls and floors that are exposed to direct solar radiation will absorb a large amount of this energy.

By introducing an amount of thermal mass in the calculation, the air in the building heats up more slowly. We assume that there will be at least 10.000 m2 of concrete present in the design, which can function as thermal mass and that is exposed to the direct solar radiation. The preliminary design includes at least 25.000m2 of floors and an undefined amount of walls, which makes it save to presume the 10.000m2 to 20.0002 of thermal mass to implement in the model.

Page 75: Living Facades

73

The heat on the thermal mass will be defined as the absorbed part of all solar radiation entering the building. This amount is dependent on an absorption coefficient, which is set at αabs.= 0,8. This means that of all the heat entering the building, 80% is absorbed by the thermal mass. The rest is reflected back to the outdoors. The warmth admittance value of the glass (60%) and the amount of glass also influence the amount of absorbed solar radiation since they determine the total amount of solar radiation entering the building.The thermal working depth of these concrete surfaces will be set at d=0.075m. The properties of the concrete are determined as ρ=2.500kg/m3; c= 1.000J/kg K; α=8W/m2 K. The heating of the floor can be determined by ΔT =Q/(V* ρ* c). In this equation, Q is the amount of absorbed heat Qabsorped which is 80% of the solar radiation qadmitted that enters the building. The volume of the working thermal mass can be 10.000m2*0.075m= 750m3 to 25.000m2*0.075m=1875m3.

If building form A with a façade of 50% glass is presumed, the amount of energy absorbed by the thermal mass of 10.000m2 on a summer’s day around noon will be Qabsorped = Q *ZTA * 50%* αabs = 3.649.280*0.6*0.5*0.8=875.827 W or 3152977 KJ in an hour. By absorbing heat, the thermal mass warms up according to ΔT =Q/(V* ρ* c). The temperature increase will be ΔT =Q/(V* ρ* c)= 3152977/(750*2500*0.840)= 2.0°C.

The higher temperature of the concrete will cause a convection heat flow from the concrete to the air by means of the temperature difference between air and concrete. The flow from the concrete can be calculated with heat transfer coefficient α, the surface A and the temperature difference ΔT. The temperature difference caused by radiation is 2.0°C, the α set to 8W/m2 K and the area A=10.000m2. The convection flow will then be q= α*A *ΔT=8*10.000*2=160.000W. This is 5.5 times less than the absorbed solar energy that entered the building. Therefore, the air in the building will warm more slowly.

5.3.6 VentilationThe most important tool for cooling the building is ventilation. Using ventilation, the warm air in the building can be replaced by cooler air from outside. For most buildings a standard amount of 30m3 air per hour per person is used to refresh air. In this way, the composition of the indoor air stays fresh and enough oxygen for every user is guaranteed.

Ventilation owes its thermal function to the replacement of air in the building. The value of the amount of replaced heat can be calculated according to Q=ρ* c*V*ΔT. From this formula it can be derived that the amount of cooling depends on air density (ρ) and specific heat (c) , which are standard parameters and on volume of air (V) and temperature difference (ΔT), which are variable. This means that both the volume of the ventilation air and the temperature of the ventilation air -and more specific its temperature difference with the air in the building- can influence the thermal impact of the ventilation.

Page 76: Living Facades

74

For extra cooling of the building, an additional amount of air can be used to replace the heated air in the interior. This means volume V will be increased. Normally for 600 people 600*30m3=18.000m3 of ventilation would be used. This amount can be doubled on sunny days to prevent the building from overheating. In this way, the cooling capacity of the ventilation system is also doubled. In case of passive ventilation, this would mean more openings in the façade. With normal mechanical ventilation this would take more of the ventilation installation. With a view to the sustainable character of the building and the energy ambitions that this need the maximum capacity of the installation will be set at 40.000m3 per hour. This means that 40% of the air in the building is refreshed every hour.

However, in summer when the outside air can be higher than the maximum comfort temperature, this might not be a sufficient solution. In that case, the ventilation air can be cooled to get extra fresh air in. Usually, in New York this is done with airco machines that vastly influence the Urban Heat Island Effect and the city’s energy consumption. A better way to cool the air is to lead it through the plants around the building. In summer, this can decrease the temperature of the ventilation air with up to 3°C (as described in paragraph 5.2.3). But on the hottest days, when the outside temperature can have a mean high of 29°C or even get 41°C, this is not enough by far.

Another way to cool the ventilation air is to cool it underground, where the temperature stays 10°C all year round. Cold from the winter can even be stored underground and used to cool the ventilation air. In this way, a ventilation air temperature of 10°C to 15°C can be pumped into the building. In this way the temperature difference ΔT between the inside air and the ventilation increases a lot.

The last important consideration for UNEC is the shape of the spaces in the building. The greened dome that is examined in this report has an height of at least 18m as defined in the building volumes (see appendix C). It is important for the interior climate that this ground floor, up to a height of 2,5 meters, is at comfort temperature. The rest of the volume can be warmer or colder. Since warm air is lighter than cool air, it will rise. This can be used in the climate concept of the building by ventilating from the bottom up. This means that cool air from the underground will enter the volume at ground level and the warm air used is transported higher up. In this way, the comfort temperature can be reached with less effort.

Page 77: Living Facades

75

5.3.7 Influence of greeneryThe first important aspect of the plants is their shading capacity. As explained in paragraph 5.2 the plants work as blinds. Their shading capacity can be described as qpassing= q*0,55^LAI in which the LAI is the Leaf Area Index of the plants that cover the shaded parts of the glass of the façade.

Because of this property, the amount of solar radiation in the building qadmitted will be not only be defined by the amount of glass or the solar admittance coefficient (ZTA) of the glass, but also by the amount of glass that is shaded by plants. For this shaded glass the solar radiation qzon will be multiplied by 0,55^LAI.

Another important aspect, as found in paragraph 5.2, is the ambient temperature around the leaves of the plants. This ambient temperature can differ as much as 3°C from the outside temperature. This temperature difference is mainly important for the convection flows through the façade.

When the interior is warmer or cooler than the outside air a convection flow (qconvection) will be started by the temperature difference. For the glass in the façade, the heat transmission coefficient U is 1.62W/m2K (as defined in paragraph 5.2.2). If the outside air is 29°C and the inside air is 25°C the heat flow will be q=U*ΔT=1.62*(29-25)=6.5W/m2 into the building. The greenery on the façade of the building will cause the ambient temperature around the façade to be 29°C-3°C=26°C. In that case, the convection heat flow will be q=U*ΔT=1.62*(26-25)=1.6 W/m2, which is only 25% of the convection flow of a façade without plants.

Another property of the living façade is the Vertical Greening system itself (see paragraph 3.2). The parts of the façade on which the plants are planted, will have a different heat transmission coefficient U from the glass U. This transmission coefficient U for these well-insulated systems will be around 0.3W/m K, which is 5.4 times better. Therefore, the area of the façade greening system should be taken into account as well.

Page 78: Living Facades

76

5.4. Calculations on climateWith the properties given in previous paragraph, a model can be made that calculates the temperature in the building from hour to hour. In this model, the solar radiation, the thermal mass, the internal heat loads, the ventilation and the influence of the greenery will be taken into account. The Excel model involved can be looked up in Appendix D.

5.4.1 Set-up of the modelThe model is made in Excel and is based on intervals of an hour. The calculation is static, which means that it is assumed that the indoor and outdoor temperatures do not change for an hour. In that time, the several heat flows only influence each other.

The model starts with the calculation of the solar radiation on the building using the methods described in paragraph 5.3.3. From the solar radiation qnormal the various relative radiations on the façades of the building qhorizontal, qvertical and qangular are calculated. This gives a matrix of radiations. Together with the quantities of the surface that face south the total amount of heat that falls on the building in an hour qsun is calculated for each of the building shapes.

After determining qsun, the radiation through the façade Qadmitted is defined. The open, shaded and closed parts of the façade are defined as coefficients in the parameters. All radiation is multiplied with the ZTA of the glass , which is another parameter defined as 0.6. The shaded parts are multiplied by 0.55^LAI. The total radiation is multiplied by 3.600 seconds to convert from Watts to Kilo Joule.

Heat Qabsorbed is calculated by multiplying the amount of heat Qadmitted by the absorption coefficient αabs from the parameters. With Qabsorbed and the increasing working depth d of the thermal mass and its ρc from the parameters, defined as 2.500kg/m3 and 0.84kJ/kg K. The temperature increase of the concrete can be found using ΔT =Qabsorbed/(V* ρ* c). This leads to an increase ΔT for the concrete with a starting temperature of 21°C.

Next, the Internal heat load is defined by multiplying the heat loads and the amounts of people, computers and square meters of lighting. This leads to Qintern, which causes temperature increase ΔT =Qintern/(V* ρ* c), with the ρ c for air defined as 1.2kg/m3 and 1.005kJ/kg K and V the volume of the shape.

Using the new air temperature and the new concrete temperature, the convection flow from the thermal mass is now calculated as q= α*A *ΔT, with α and A from the parameters quantified as 8 W/m2K and 10.000m2 to 25.000m2 and ΔT the difference in temperature between the air and the concrete. The convection flow is only directed from the thermal mass to the air, to exclude

Figure 5.17: Excel model

Page 79: Living Facades

77

fluctuations in convection caused by the static approach over an hour and to prevent large accumulations of heat to heap up in the concrete.

With the convection heat from the concrete (Qconcrete), new air and concrete temperatures are calculated. Then, the amount of cooling by ventilation is subtracted from the air temperature. The ventilation capacity can be adjusted with an extra amount of cubic meters air on top of the required 18.000m3.

The last step of the model is to calculate the convection flow between the inside and the outside by determining the temperature difference between the newest air temperature and the outdoor temperature. For the glass parts of the façade, the convection flow uses the U= 1.62W/m2K of the glass. For shaded parts, a difference in ambient temperature is subtracted from the outside temperature in summer and the amount of solar radiation is multiplied by 0.55^LAI with the LAI as a parameter to implement the amount of shaded radiation. For closed parts the lower ambience temperature and a U-value of 0.3W/m2K are taken into account.

After this last step, the last air temperature can be calculated. This is compared with the upper and lower comfort temperature compared to the outside temperature. If the model stays within these limits, it is found to be satisfactory.

5.4.2 Outcome of the modelIn the model, the optimal setup of the façade to keep the indoor temperature in the comfort zone, appears to be a 30% to 55% closed façade with glass that is 40% to 65% shaded in summer and 15% to 30% shaded in winter, dependent on the building shape. A leaf area index of 1 appears to be enough to shade the glass well. The ventilation air used to cool the building is 15°C in summer and 10°C in winter. The extra ventilation increases to 25.000m3 extra in summer and is needed most between 12:00 and 20:00. There is no extra ventilation in winter. For all building shapes a thermal mass of 15.000m3 seems to work best.

The first that strikes us in the model (see next page), is that the building shape greatly influences the amount of solar radiation on the building. Shape E has the least solar energy falling on its surface in summer with 159.767MJ over the day. This can be explained by the compact shape. Building shape C catches most solar radiation in summer with a total of 183.324MJ. In winter, shape D finds the least radiation on its façades with 37.752MJ and shape B the most with 63.928MJ. This can be explained by the solar elevation. In summer, the sun rises up to 72.6° high, while in winter it only reaches 26°. This means that vertically oriented shapes (like shape B) get more solar radiation in wintertime, because the rays stay almost horizontal throughout the day. In summer, the sun shines on the roof surfaces and therefore this vertical orientation does not make a difference, compared to a horizontal one. Compactness of the volume does make a difference in summer, when the compact shapes A, D and E get significantly less radiation.Because of these differences the shapes also require different percentages of opened, closed and shaded façade. The next tables show radiation (in MJ) and percentages of shaded glass and living façade per building shape, optimized for the interior climate (see appendix C).

Page 80: Living Facades

Summer: A (MJ) % B (MJ) % C (MJ) % D (MJ) % E (MJ) %Qsun-admitted 37 100 39 100 33 100 33 100 34 100Qinternal 5,2 14 5,2 13 5,2 16 5,2 16 5,2 15Qconcrete 5,4 15 6,1 16 5,8 18 5,5 16 5,4 16Qconvection -0,12 0 -0,16 0 -0,11 0 -0,10 0 -0,07 0Qventilation 9,9 27 10,5 27 10,3 31 10,0 30 10,0 29

Winter: A (MJ) % B (MJ) % C (MJ) % D (MJ) % E (MJ) % Qsun-admitted 15,4 100 19,6 100 11,1 100 11,6 100 13,7 100Qinternal 4,6 30 4,6 24 4,6 42 4,6 40 4,6 34Qconcrete 0,7 4 3,7 19 0,2 2 0,5 5 0,9 7Qconvection -2,3 -15 -2,0 -10 -1,9 -17 -2,0 -17 -1,9 -14Qventilation 2,8 18 2,6 13 2,7 24 2,6 23 2,7 20

Summer: A (MJ) % B (MJ) % C (MJ) % D (MJ) % E (MJ) % Qsun 160 100 182 100 183 100 158 100 160 100living façade 35 40 50 40 40shade 60 55 45 55 55Qsun-admitted 37 23 39 21 33 18 33 21 34 21

Winter: A (MJ) % B (MJ) % C (MJ) % D (MJ) % E (MJ) %Qsun 46 29 64 35 41 22 38 24 43 27living façade 35 40 50 40 40shade 20 20 10 20 15Qsun-admitted 15 34 20 31 11 27 12 31 14 32

The façade division in closed, shaded an open parts was determined by creating a minimum amount of closed parts in combination with 5% of uncovered glass, that sufficed in the summer situation. After this, the amount of closed parts was adjusted for the winter situation. In winter time especially, building C with its horizontal oriented shape does not receive much heat. The heat load by solar radiation for shape B is only 22% of the summer situation. To prevent a large convection flow from the inside out, the façade needs more closed surface with a lower heat transfer coefficient. This helps the building to stay warm.

In the tables below, it can be observed that the amount of solar energy admitted into the building is the biggest heat flow in the model. The thermal mass helps storing the largest part of this energy and about 15% is released to the indoor air. The amount of closed parts with a Vertical Greening System that blocks the sun, therefore also has a large influence on the indoor temperature in summer and in winter. When the closed parts are changed with only 10%, the temperatures on average increase with 1.2°C in summer up to 5°C in the afternoon.

Figure 5.18: Building shape

Page 81: Living Facades

79

The amounts of admitted solar radiation (Qadmitted) are displayed in the graph on the right. The peak of the curves for building form C and D are the highest. This can be explained by the horizontal explanation of these building forms. Building B, which has a vertical shape, has the lowest peak at noon. The curve of the ventilation energy rises during the day. The internal energy is mainly released between 8 a.m. and 6 p.m.

In summer ventilation is the second largest flow. An increase or decrease of 5°C in the temperature of ventilation air makes a difference of 1.5°C on the indoor temperature in summer. If the ventilation volume is adjusted to 10.000m3 more per hour, the temperature drops with 1.3°C on average in summer.

A doubling of the thermal mass to an Area of 30.000m2 makes a difference 0.5°C in summer up to 2°C in the late afternoon. The building heats up more equally with a bigger thermal mass. If the thermal mass is downsized to 1m2, for example, the temperature of the air in the building heats up and cools down faster and the afternoon, the temperature rises up to 15°C, but also falls back quickly in the evening.

In winter, the internal heat load plays a big role in the heat comparison. This heat load is as big as 40% of all solar radiation that is admitted into the building. As a result there will be a temperature rise of 2°C almost instantly, if the amount of people in the building doubles on a special occasion. This means that the extra ventilation capacity will have to be used on special occasions in winter.

5.4.3 ConclusionsIt can be concluded that the most important issue for the façade is the prevention from overheating in summer, by shading the façades oriented on the sun from direct radiation. This means that most of the glass in the façade should be covered by greenery in summer in order to keep the sunlight out. The most optimal façade setup between all these parameters appears to be a façade that is about 40% closed and 60% open. For horizontal volumes, this would more approach a 50%/50% proportion. Only 5% of the glass should be kept open in summer. In winter, this proportion can be 40% to 45%. This conclusion holds only true for south oriented and horizontal planes, because they take in the solar radiation. North oriented façades can have more open surface, because they do not receive direct solar radiation.

The detailing of the façade would have to focus on the provision of shade and coverage by greenery for the façade on the south side. To overcome heat losses with storage and distribution, it would be cleverer to gain more heat in winter and less in summer. Therefore, it would be smart to use or facilitate deciduous plants on the façade that shade the glass. In winter these plants lose their leaves and let in more warmth.

Figure 5.19: Energy amounts (KJ)

Page 82: Living Facades

80

The ventilation air should be cooled in order to reach the desired comfort temperatures when the building is exposed to sun. The cooling capacity of the ventilation should be able to deliver an extra 25.000m3 of air, which is a 250% increase to the normal demand of 18.000m3.

At least 15.000m2 of thermal mass is needed to absorb direct radiation. This can help to slow down the warming of the building and to be able to control it with ventilation. A bigger thermal mass is not necessary but is welcome. Less will cause the building to heat up too rapidly when exposed to direct radiation, which leads to an excess of the comfort temperatures.

Page 83: Living Facades

81

5.4.4 Evaluation of the modelThe output of the Excel model can be considered as very useful for the determination of the global proportions of the façade. It should be understood however, that although it is semi-dynamic, it contains a large error.

The first important difference with the real situation is that the model excludes the azimuth of the sun and only uses south orientation. This means that a difference in width of the building volume does not influence the solar energy admitted, while in practice this does matter.

There is, however, a bigger error to be found in the static calculation by the hour, namely, the fact that the model uses consecutive calculations for each aspect of the energy balance. For example, all the solar energy admitted per hour is stored in the concrete, which therefore reaches a very high temperature and only then is released under the temperature difference ΔT of the new situation compared to the air. In practice the interaction with the air would immediately start after the first solar energy falls on the concrete, which would mean an interaction with a smaller ΔT. The static approach can cause the concrete to release so much heat under the static ΔT that it even gets cooler than the indoor air. This causes the concrete to absorb energy from the indoor air during the next hour. This would never happen in the dynamic reality. A part of this error is kept out of the model, by making release out of the concrete possible in one way only, but the consecutive order still creates temperature differences ΔT that would not occur in reality.

In winter, the biggest errors with this static approach occur. According to the static calculation the admittance of solar energy and the warming of the air caused by that, do not help to warm the building, but, instead, only increase the convection flow to the outside disproportionally. This is caused by the higher temperature difference between in- and outdoor air, that arises when the solar energy of a whole hour is admitted. The disproportionate convection flow leads to an enormous amount of heat leaving the building in the model. Instead, if the whole building is shaded, the indoor temperature rises, because the temperature difference used to calculate the convection flow, is determined after the release of heat from the concrete, and is then smaller, which causes a smaller amount of energy to leave the building. In practice of course, this will not be the case and extra solar energy will only cause the building to warm up more.

Another aspect is the fact that the model uses an overall proportion for open, closed and shaded façade parts. In practice however, there is a difference between the north and south façade. The north façade can be fully glass in summer, because it does not intercept solar radiation and therefore does not influence the overheating of the building. In winter, the convection flow through the façade should determine the proportion on basis of the U-value of the glass (1.62W/m2K) or Living façade (0.3W/m2K).

Still, the model gives insight into the different parameters used in the model. Especially the total amount of energy for the different aspects show their influence and coherence.

Page 84: Living Facades

82

Page 85: Living Facades

83

6. façade criteria (conclusions)

6.1. Comparing systems on sustainabilityIn this paragraph, a comparison is made between the possibiliy of the four fundamental vertical greening systems to exploit the sustainable aspects that plants have. A ‘+’ sign means that the benefits on this point are high; a ‘–‘ sign means that the system does not provide a lot of benefit.

Modular green system

Industrial felts system Façade greening

Vegetative tiles or stony surfaces

Urban agriculture + ++ -- --Bio filtration ++ - + --Air quality ++ ++ + 0Noise reduction ++ + 0 -Biodiversity ++ + 0 0Social & psychological ++ ++ ++ +Water cycle ++ + + 0Heat island ++ + + 0Heat + + ++ -

The modular green system is suitable for all aspects. Because of the soil in the containers the system can reduce more noise; more water is present, which contributes to the small water cycle and reduction of the Urban heat island effect; any kind of crop can be grown for Urban agriculture (dependent on the system depth and slope) and even bio filtration is possible in the containers that hold the soil and plants. Condition for this good rating is that the plants get enough water, which can be achieved manually or with a watering system as in the industrial felts system.

Industrial Felts systems, or systems using a similar hydroponic technique, are more artificial and can be optimized best for urban agriculture. This artificial character however, offers almost no possibilities for (natural) increase of biodiversity. The growing medium is inert and has less capacity to hold water than the soil in the modular system and this leads to fewer possibilities to improve the water cycle, diminish the heat island effect and promote bio- filtration of waste water or vegetable waste.

The façade greening system uses climber plants that grow from the ground or containers over the building and therefore uses less soil than the modular system. This leads to fewer possibilities to improve the water cycle and heat island effect. However, this system can be more usable for bio-filtration, if containers are implemented. Noise reduction is less, because of the lack of extra mass or cavities compared to the first two systems. Urban agriculture is not possible, because this system is limited to the use of climber plants, which distinguishes it from the modular green system. It can be very useful to apply as solar shading and therefore it has a high score on heat.

The system with vegetative tiles or stony surfaces offers least optimal conditions for the sustainable properties of the plants. The vegetation on this system is less

Page 86: Living Facades

84

dense and high and therefore less optimal. Also, there is no possibility for the containment of water and the system is only usable for a smaller group of plants. These small plants are less capable of shading, filtration, evaporation or other aspects.

The focus on the sustainable aspects of the façade inverts the choice of the system, compared to the scores on technology. In the technological comparison the Façade Greening system and Vegetative tiles or stony surfaces scored better. (see the table from paragraph 3.2.5: below)

Modular green system

Industrial felts system

Façade greening

Vegetative tiles or stony surfaces

Weight - + ++ --Vegetation diversity ++ + 0 -Maintenance -- + - ++Installation - -- ++ 0Complexity 0 - + ++Water use + -- ++ -

In the focus on sustainable aspects the Modular Green system and Industrial felts system score better. This shows how the scope of a project can lead to different choices for the façade system.

Page 87: Living Facades

85

6.2. Criteria stemming from sustainable aspectsIn this paragraph conclusions are drawn on the implementation of the sustainable aspects and their importance for the building, the city and the environment. In the following table the importance of the several criteria is listed:

ImportanceUrban agriculture --Bio filtration +Air quality ++Noise reduction +Biodiversity +Social & psychological 0Water cycle ++Heat island ++Heat +

Urban agriculture is not important for the façade. Urban Agriculture had better take place in towers in which crops can be planted and harvested with greater efficiency. The labour on the façade will also cause nuisance and discomfort for the building users. Together this gives a negative score for this aspect.

Bio filtration is an important way of filtering contaminants from the environment. Especially in cities like New York, a lot of contaminants are present and the property of plants to clean soil, rainwater and wastewater can thus be used. To cleanse the wastewater of the building users, about 6.000 m2 of bio filter would be needed. This is represented by the green square on the building area in the picture on the right. As we can see, almost the whole roof has to be implemented as a biofilter to achieve this amount.

Air quality is a very important aspect to which plants can contribute. Most of the city’s air pollution comes from thousands cars that are in traffic jams every day in the middle of the city. The plants on the façade can help diminish this air-pollution. For the purpose of air quality, as many plants as possible should be realized. In terms of CO2 reduction an amount of greenery of 21,75 times the site area would be needed. In terms of O2 production 150 trees would be needed.

Figure 6.1: Bio-filtration area

Page 88: Living Facades

86

Noise reduction is an issue in a busy bourough like Manhattan. The plants on the façade can contribute a lot to the sound isolation of the building. Also, the plants can help the outdoor environment by their sound absorption behaviour. In the map on the right, the places with most noise are shown in red. The heavier systems should be applied in the reddest places.

Biodiversity is an important aspect with a view to the ‘Green city’ theory that was described earlier. There are numerous species of birds and plants in the state of New York, but the city of New York lacks those. Quantitative needs cannot be given for this topic, but it would be a nice aspiration to make a living façade suitable for as many species as possible.

Social and psychological aspects come with the plants on the living façade. As with the biodiversity topic, quantitative needs cannot be given. It would be nice though, to provide as many views with greenery as possible to comfort the human eye and mind.

For the water cycle as many plants as possible should be present on the site. Since Manhattan is a clad and stony place, problems with rainwater run-off occur a lot. The building can contribute to problems like these by diverting rainwater run-off from the façade into the soil or another medium.

The Urban Heat Island effect is a major problem in New York. Every site in the city should contain plants to contribute to solving this problem. For this reason, it is crucial that vegetation covers a large amount of the total surface of the building façade. In this way, solar energy is transformed into Latent Heat and does not warm the city. In order to be able to transpire, the plants need enough water.

Heat is an important criterion to shade the glass on the south side of the building with deciduous plants. To encourage these plants, the system should be kept moist. If there is room for water absorption in the living façade system, the rain can provide water to encourage these plants. If there is no absorption capacity, the system should be well irrigated. A façade greening system applied on the outside of the glass would be most efficient to shade the glass. The ideal façade would be at least 40% closed, with a living façade system; of the 60% of glass remaining only 5% can be exposed to direct solar radiation in summer.

Figure 6.2: City noise

Page 89: Living Facades

87

6.3. Principle detailsThe two systems that suffice most for the façade cladding of the building are the Modular green containers and the Industrial felts. In this paragraph the implementation of these systems on the façade is investigated. First, the standard detailing for horizontal, vertical, angular and curved surfaced will be determined and discussed (phase 1). After this the influence of the sustainable aspects on the detailing will be discussed (phase 2). (see drawings appendix E)

6.3.1 Façade division

The façade of the preliminary design consists of two types of surfaces that are vegetated (see picture above). First, there are large plains of living façade (1). These plains have big dimensions and cross several construction elements. On the sides they border glass and the second type of green surface (2). This second type of living façade is formed by plants that are positioned on the construction elements in large glass panes. These strokes of living façade border glass on two sides.

Detailing is made for both types of plains. As a basis, a construction from IPE300 beams is used. In between the beams a layer of corrugated steel sheet is attached with welded steel strips to create large plains (1). On top of this steel sheet a layer of wooden finish is mounted. The construction is isolated with 100mm insulation and waterproofed with a watertight layer. For the strokes of planting (2) on the IPE beam, the upper flanges are broadened with a steel strip.

Figure 6.3: Types of facade plains

Figure 6.4: Basic construction

Page 90: Living Facades

88

On top of these strips the window frames are fixed with a 100mm of insulation in-between and a watertight layer on top.

6.3.2 Implementation of systemsFor the modular green container system, a panel of 500x500mm is chosen. This panel has a depth of 100mm. When the panel is attached vertically, it contains 9 slats with an angle of 30° to the vertical plane; for an angular situation of 45° the panel contains 4 slats; if attached horizontally the panel has no slats. For every 10° angle difference a slat is added. The horizontal containers are provided with extra drainage mats.The containers are attached on a frame that is connected with the main construction by steel rods that perforate the insolation layer locally. The containers are attached on this frame with standard pins that fit in each side of the container and are screwed into the metal frame.

In flat plains the containers fit tightly next to each other. To make angles or curves the containers have to be used under different angles and chinks occur in between the panels.

The industrial felts system is made up out of several layers of felts on a waterproof plate material. The irrigation tubes are put between the felts and perforate the plate locally to be connected to the main water supply tube that runs behind the plates. The plates are screwed on metal tubes that are fixed to the main construction with metal rods.The felts can be attached seamlessly over angles and round surfaces. The plates are bended over a round main construction to create arc shaped sections.

6.3.3 Water and dirtThe water run-off from the systems contains soil, vegetable waste and other dirt and thereby pollutes the glass of the façade heavily. To prevent the glass from being smudged, steel strips are introduced around the glass in an extra frame that is fixed into the window frame. This causes the water to run around the windows instead of over the glass. When the façade is put under an angle, the lower strip around the window is removed. This provides an opening for rainwater to leave the window frame and wash the glass as well. On vertical façades, a gutter is put on the top side of the window that redirects the water around the window. The water surplus of water can run away behind the greening systems over the watertight layer of the basic construction.

Figure 6.6: Vegetable waste

Figure 6.5: Modular Green System

Page 91: Living Facades

89

To make the façade accessible for service maintenance steel grating plates are added underneath the windows to walk on. These plates are attached onto rods that are welded onto the main construction. The grating allows rainwater to pass and plants to grow. When windows are heavily polluted they can be cleaned from these paths.

6.3.4. Implementation of sustainable aspectsThere are several sustainable aspects that can be realized and maximized in the façade. In paragraph 6.2 the ones with most potential are defined as heat, bio filtration, air quality, water cycle and the heat island heat effect. Of these aspects the improvement of air quality can only be realized by a maximization of plants. The others aspects can be improved by the technical detailing of the façade. These detailing propositions are shown in the phase 2 details.

To prevent the building from overheating in summer the glass should be shaded from the sun. This shading can be realized by combining the basic detailing with a façade greening system that runs over the glass. The climber plants are planted around the sides of the windows and cables run in between the steel strips that border the glass. In this way, the climber plants can grow over the glass and shade it from sun in summer. The cables have to be kept at a distance from the façade to prevent the plants from growing onto the rest of the façade. The plants can be guided or trimmed once a year from the maintenance paths on the lower side of the window.

Bio filtration can be implemented in the façade as well. For a horizontal system, a container with a minimal depth of 600mm is needed. This container can only be placed on horizontal parts of the façade where it does not interfere with the rainwater run-off, the depth of the façade or the appearance of the façade. It is possible to place this container on horizontal parts of the façade, but this has large influence on the dimensions of the main construction.

Figure 6.9: Shading

Figure 6.7: Window frame Figure 6.8: Maintenance path

Figure 6.10: Trellis structure

Figure 6.11: Biofiltration

Page 92: Living Facades

90

To improve the water cycle the rainwater run-off from the façade has to be kept and infiltrated on the site or on the building. There are possibilities to infiltrate the rainwater on the façade. The phase 2 details that are in an angle, therefore contain a gutter underneath the windows. Here the biggest flow of rainwater is expected to pass. By introducing a channel with soil -or another water absorbing growing medium- and plants the rainwater does not directly run off the building but is collected first and can be infiltrated in the façade.

On an average rainy day, 10.9 mm of water is expected to fall on the façade. This means that every m2 on the horizontal plane gets 10.9 L of water. To infiltrate this water the infiltration gutters will need enough volume. In the phase 2 details of angular parts of the façade the glass next to the gutter is 1m wide and every m2 of glass covers a horizontal plane of 0.6m2. This means the gutter will need a capacity of 0.6m2 * 10.9mm = 0.00654m3= 6.54L to intercept the rain running from the glass. In heavy rainstorms the surplus of water can run over this channel and continue its path over the façade where it can also infiltrate the felts or modular green containers. In this way water is saved on the living façade.

The Urban Heat Island Effect can partly be solved by the transpiration of the façade. In order to sustain these transpiring capabilities the plants should be provided with water. In the felts system the plants are irrigated and wilting will not occur, as long as the system provides enough water. The modular green containers do not make use of an irrigation system. To improve water supply to the plants this system can be introduced in the detailing of the façade. However the panels do not leave space to penetrate the surface of the façade. This necessitates the installation of the irrigation system to be installed onto the façade. The sprinklers are planted in the soil in the containers. The tubes run over the containers and can be attached locally to the container to keep them in place. Now the modular green container system can also be supplied with water.

Figure 6.12: Irrigation

Figure 6.13: Infiltration & irrigation

Page 93: Living Facades

91

6.4. Influence on the building designThe living façade and the technical details shown in the appendix have an influence on the design of the rest of the building. First of all, the weight of the system is an important variable for the construction behind the façade. Second, the cleaning and maintenance aspect necessitates the building to have an approach to the façade for cleaners and repairmen. Finally, the water for the irrigation system needs to be transported to all parts of the façade.

The weight of the system is significantly more in case the Modular Green Container system is implemented. The building will need a stronger construction in the case of the implementation of the containers compared to implementation of felts. The weight of the façade can also be influenced heavily by the option to implement water related solutions such as the irrigation, bio-filtration and water infiltration aspects. Of these, the bio-filtration will be the most heavy, as it includes a container full of water, soil and biomass with a depth of 600mm. This makes its weight per m2 container more than 600kg/m2. This is an enormous increase of weight to the façade compared to the 30kg/m2 for the industrial felts system or the 244kg/m2 for the modular green containers. Therefore, the façade will need extra support in places where the bio-filtration system is added. The water infiltration gutter can add quite some mass too. In the principle details shown in the appendix this is only less than 10kg/m construction, so it will not influence the design of the construction a lot. If the gutter becomes bigger, extra construction height will be required. The irrigation system itself can be very light and therefore will have small impact.

Cleaning and maintenance personnel need access to the façade and the maintenance routes that are built on it. This means that an possibility to climbe onto the façade and step onto the maintenance path will have to be provided. This could mean that a ladder onto the façade from the ground up should be included in the building design. Another option is to create accessibility from the top down through a hatch. In the last case vertical transport inside the building to the hatch is needed. This can influence the internal setup of he building.

The water for the irrigation system also needs to be transported to the façade. This can come from a rainwater retention storage or from the local waterworks. For reasons of sustainability and water usage the first option is desired. The retention can take place on the façade as well as on the ground. If it takes place on the façade, the irrigation system will need reservoir space on the façade. If it takes place on the ground the reservoir will have to be placed somewhere in or around the building. In that case the rainwater also has to be transported back onto the façade from the reservoir. This could mean that extra shafts are needed in the building.

Page 94: Living Facades

92

6.5. EvaluationThe implementation of the modular green system or the industrial felts system is desired to improve the sustainable qualities of the façade. They both have their advantages and disadvantages , which can influence the building design. Dependent on the shape of the building either one of both has to be chosen.

In the technical details in Appendix E it is shown that the detailing for the modular green façade only works on flat surfaces. Rounded surfaces cause many assembly and fitting problems. When the containers are placed under an angle, chinks occur in between the containers. For the detailing of the stroke-like surfaces, the container also does not suffice. Its fixed dimensions cannot easily be fitted onto the narrow stroke. A minimum width of 650mm is the result with a container of only 300mm broad.The modular green container does have the best sustainable properties. This is mostly caused by the use of soil. The soil has many capacities that contribute to its sustainable character.

The Industrial felts system provides a better detailing for all kinds of angles and curves. This makes it better suitable for complex shapes. The felts can be bent and thus fixed onto any shape , which makes this system a very attractive option.The detailing for the stroke surfaces can be made smaller than the 650mm with the felts. The smallest dimensions depend on the size of the roots of the plant that has to grow on the stroke. Sizes of only 200mm broad are possible, though.The sustainable properties of the felts are less optimal. As it is a synthetic material that needs a highly technical detailing and precise construction, the integration with nature is less optimal. Therefore it especially scores less on biodiversity.

The choice for either one of these systems depends on the final building shape. If the building has a complex or curved shape the felts can be used best. If the building has a simpler shape the modular green façade detailing would apply. In that case the sustainability of the façade is optimized the most.

Figure 6.14: Soil Figure 6.15: Felts

Page 95: Living Facades

93

7. implementation in architecture (Drawings of the final design can be found in appendix F)

7.1. Final designThe goal of the project is to create a design for a recognizable sustainable icon that finishes the UN international territories on the North side; which makes use of its environment to sustain itself in terms of water, power and temperature regulation and which complements the green space of the existing park. The design should also accomplish a balanced architectural configuration on the plot with the existing UNHQ and resolve the security problems as well as deal with the different flows of people that use the building. The project’s difficulty lies both in resolving the sites architectural configuration and in creating a sustain-able icon.

The UN site is a piece of land with the status ‘international territory’ ,which faces many problems concerning safety and control of the location. The UN Headquar-ters with its strong geometry and monumental status, designed by a team of 13 international renowned architects, also forms a challenge to add (up) to.

Next to these problems of handling the site and the relation to UNHQ, the ques-tion ‘how the building should represent its function’ is an important issue in the project, or, in other words, ‘what a sustainable icon should look like’.

In the design the biggest problem of UNHQ, the presence of FDR-drive, is man-aged by relocating this highway in a four- lane double level tunnel in East River, with a public park on top. In this way, the waterline recreational zone of Manhat-tan can be completed. The international territories are transformed into a po-dium again, as it was meant in the original design. UNEC is located on the north side, which was also originally intended as a space for an extension. In this way the plot gets a clearer border on the North side. The ground near the General Assembly is lowered to create an entrance under the podium of the Assembly. By this mean, the security checkpoint in the temporary security tents on the podium can be moved to the basement of the Assembly.

The program of the UNEC building demands a large amount of offices and a lot of meeting, gathering and exposition functions. These office functions ideally need a space with a maximum depth of 14 to 15 meters between the facades to create an efficient surface in terms of daylight and floor layout. The other functions could also fit in this dimension, but ideally need to be interconnected on the horizontal plane to create an informal landscape that could be discovered by visitors. Thus, the building is split up into the office functions, which should be fitted in a volume with a maximum depth of 15m, and the other functions, ori-ented in a horizontal configuration. This division somewhat resembles the con-figuration of UNHQ that consist of an office slab and a configuration of volumes on ground level that houses library, exposition and gathering functions.

To maintain the park that is present on the plot, the north side is lifted and space for the horizontal functions of UNEC is created underneath. This space is

Page 96: Living Facades

94

shaped like a dome in order to deal with heat flows and ventilation of the space in a more natural way. Hot, used air streams up and accumulates in the top of the dome, while new fresh air is inserted on ground level (see paragraph 5.3.6). From the outside, the lifting of the landscape testifies to the fact that the most important functions of the building are located under the landscape. Also, the hill creates a green wall on the north side of the international territories and thereby provides a more intense experience of the amount of vegetation on the site, which improves psychological aspects (see paragraph 4.6). The dome has windows for daylight and heat retention. These windows are larger on the north side and in the more horizontal parts, where the plants can shade the glass.

The offices are shaped into a tower with an interior depth of 14,5 meters. This tower uses a minimum amount of surface in the park by its configuration in 16 stories. It is inserted in an incision in the hill and an entrance area is created in front of it, which equals the function of the podium to the assembly of UNHQ. With its clear building volume, the office tower signals the presence of UNEC and especially its entrance. The amount of glass in the tower is maximized for view and light. It is acclimatized by a second skin façade with openings on the in and outside. In winter, this façade can be fully closed to create a temperature buffer; in summer the outside can be opened 50% to cool the cavity. In spring and autumn, the offices can be opened to the cavity as well as directly to the outdoor environment (25%). The floors inside are adjusted to fit every type of of-fice space with their depth of 14.7m. The corners of the tower have solar chim-neys implemented to ventilate the dome.

With the spatial configuration of the combination of a hill and a glass tower, the UNEC building is an example of the broadness of the term ‘sustainable building’. Building under the landscape is one of the oldest ways to create naturally insulat-ed and acclimatized buildings and therefore represents the old modus of build-ing sustainable by using nature. The office tower represents the modern way of sustainable building by implementing high tech solutions.

The materials of the building are all assembled dry for the purpose of recycla-bility. The construction of the parking garage is made of prefab concrete. The dome and tower are constructed from steel. The tower is made with lightweight combined steel-concrete floors that create space for ducts and pipes above the ceiling. The interior landscape under the dome is made with Manhattan Schist from the subway excavations. The volumes that pierce through them are clad with translucent opaque glass panels. The auditoriums inside these volumes are clad with bamboo slates.

In front of the building, on the lowest part of the site, rainwater is harvested into an underground cleansing facility. Heat and cold are stored in a PCM-plant underneath the office tower. In winter, ventilation air is heated here, in summer it is cooled. The plant also provides warm water for the floor heating in the offices and cool water for the cooling ceilings. Energy is created from tidal turbines on the wall of the highway tunnel and from PV-cells on the office tower.

Page 97: Living Facades

95

7.2. Choice of the living façade systemAccording to the evaluation (in chapter 6.5), the choice for implementation of either the industrial felts system or the modular green system can be made on the basis of four important criteria: complexity of the surface, broadness of the surfaces, sustainable properties and weight.

In terms of complexity, the surface of the volume can be described as a double curved surface. This could mean that the implementation of the flat modular green container system is less suitable compared to the industrial felts. The fit-ting of these containers is, however, dependant on the sharpness of the angles of the surface. In this case, the minimum radius of the surface is about 70m. For the containers with measures between 300 and 600 mm, this radius does not present big fitting problems. This aspect can therefore not exclude a system, but it does lead to a preference for the felts.The broadness of the surfaces cannot make a difference between the choice of systems, because the openings in the living façade are always more than 600mm apart.

In terms of weight, the difference between the systems is quite big. The 244kg/m2 of the modular green system is more than eight times the weight of the industrial felts system, which is only 30kg/m2. In structural analysis, this input of 0,3 to 2,4 kN/m2 is combined with the load of people on the roof (1,0 kN/m2), which will occur in case of maintenance, the load of services ( 1,5 kN/m2 for sprinklers and irrigation etc.) and the load of the roof under the living wall sys-tem (1,0 kN/m2). This results in a load of 3,8 to 5,9 kN/m2 on the construction. This construction also has to bear its own load over a distance of almost 69,6 m. It appears from the analysis that the span and the stiffness of the total construc-tion itself is more significant to the beam measures than the load difference of 1,1 kN/m2.

In terms of sustainability the modular green system would be the best choice. The building should be an example for the sustainable building practice, which gives this system a preference over the industrial felts system. Because this as-pect is strongly related to the architectural ambitions of the project, the modular green container is chosen. This despite the fact that the industrial felts system is lighter and would require a little less construction.

Page 98: Living Facades

96

7.3. Implementation of the façadeSystem:(for requirements see paragraph 6.4) The modular green containers are put on a different construction than in the preliminary construction details (see chap-ter 6.3). The construction of the hill consists of tube profiles. On these profiles, wooden plates that are finished with acoustic spray for insulation from the inside of the building , are mounted. The plates carry the insulation and waterproofing layers and also the construction for the modular green system, which is mounted on the watertight layer. The necessary maintenance paths run in diagonals over the façade, on the lower side of the windows. The irrigation system, which is connected to the rainwater retention facility, is provided with water from pipes under the maintenance path.

Heat:To deal with heat from direct sunlight into the building, the windows of the dome are provided with nets to grow climber plants on. These climber plants can provide the necessary shading (see chapter 5). The climber plants are plant-ed in separate planter boxes to ensure they do not overgrow other species. The nets over the windows are tightened with cable tensioners on two sides of the window. The planter boxes are on a third (top) side. On the bottom side of each window, a maintenance path of steel grate panels is mounted onto to construc-tion.The amount of openings in the dome is limited to 45%, which makes 55% of the dome closed. This means the dome measures up to the maximum amount of living façade within the boundaries of the amount of openings needed in the façade (see chapter 5.4.2). In this way, the maximum amount of plants can be realised, which is desirable for most of the sustainable aspects.

Figure 7.1: Top view of the roof

Page 99: Living Facades

97

The cooling for the ventilation air is drawn from the PCM-plant in the basement. This PCM plant has a volume of 18000m3. If, for example the PCM Natriumhydroxide in hydrogen peroxide (NaOH.31 / 2H20) is used, the thermal capacity of plant becomes 18000m3 * 1000dm3 * 300kJ/dm3 = 5.4*10^8 kJ energy storage. This amount is enough for 2,5 months of cooled ventilation air with the daily need of 7,3*10^6 kJ per day that is needed in the summer situation according to the Excel model (see paragraph 5.4.2, graph and table below).

HourTotal ventilation (m3) ΔT Total enery (kJ)

5:00 18000 5,4 117223,26:00 18000 7 1519567:00 18000 8 1736648:00 28000 9 3039129:00 36000 10 43416010:00 36000 11 47757611:00 36000 12 52099212:00 38000 13 59576413:00 43000 14 72601214:00 43000 13,5 70008315:00 43000 13 67415416:00 43000 12,5 64822517:00 43000 12 62229618:00 43000 11,5 59636719:00 43000 11 570438TOTAL 7312822

Figure 7.2: Latent heat of fusion PCM materials

Page 100: Living Facades

98

The PCM plant can be cooled down with water from the East river 7,5 months per year. In summer nightly cooling with air will be needed on nights with a tem-perature of 15°C, or below. The buffer of 2,5 months will make sure the hottest month,

Biofiltration:The aspect bio filtration is not implemented on the façade because of the enor-mous load the filtration containers add to the construction. Instead, bio-filtration tanks are situated on the east side of the plot to separate the park from the podium of the International Territories. This bio-filtration plant has a width of six meters and an area of 3.000 m2 and can thereby cleanse at least half of the waste water from the building.

Water:There are no extra water retention measures added onto the façade. Instead, the water is retained on the lowest level of the location. In the basement of the building a water filtration and storage plant is located to clean the rainwater and make it suitable to flush the toilets and use as irrigation water for vegetation. The run-off from 18.000m2 of the site runs to this plant due to the curvature of the site. In this way, an amount of 22.700m3 of water will be retained each year.

Figure 7.3: Temperature of East River

Page 101: Living Facades

99

literatureNY Flora Association. n.d. http://newyork.plantatlas.usf.edu.

Arup Engineers. City farmer news. 2009. http://www.cityfarmer.info/2009/12/28/vertically-integrated- greenhouse/ (accessed november 2010).

ATCO, Structures & Logistics. “Environmental Noise Control Handbook.” 2001.

Atwell, Brian, Paul Kriedemann, and Colin Turnbull. Plants in action. South Yarra: Macmillan Publishers Australia, 1999.

Bosschaert, Tom. Except - Large scale urban agriculture. September 2008. http://www.except.nl/consult/largescaleurbanargriculture/ largescaleurbanagriculture1.html (accessed October 2010).

Breuer, Lutz, Klaus Eckhardt, and Hans-Georg Frede. Plant parameter values for models in temperate climates. Giessen, Germany: Institute for Landscape Ecology and Resources Management, Justus-Liebig-University, 2003.

Bruse, M., M. Thönnessen, and U. Radtke. PRACTICAL AND THEORETICAL INVESTIGATION OF THE INFLUENCE OF FACADE GREENING ON THE DISTRIBUTION OF HEAVY METALS IN URBAN STREETS. Cologne: Department of Geography, University of Cologne, 1999.

Burchett, M. Interior plants for sustainable facility ecology and workplace productivity. Sydney, Australia: University of Technology, 2009.

Coder, Dr. Rim D. Identified Benefits of Community Trees and Forests. University of Georgia, 1996.

Costa, Peter. Acoustics. Rentokil Research and Development, 1995.

Costa, Peter. Constructive Use of Vegetation in Office Buildings. London: South Bank University, 1995.

Cyckowski, Laura, and Paul Grobstein. Serendip. july 2009. http://serendip.brynmawr.edu/exchange/reality/looklike.

DEP, New York City Department Environmental Protection. “New York City’s Wastewater Treatment System.” 2007. http://www.nyc.gov/html/dep/pdf/wwsystem.pdf (accessed Juni 2011).

Department of health. The New York City Community Air Survey. New York: NYC Health, 2009.

Page 102: Living Facades

100

DESA. Report of the World Commission on Environment and Development. New York: The United Nations, 1987.

DGMR. “Tabellarium.” 2005.

EPA. National Ambient Air Quality Standards. 2010. http://www.epa.gov/air/criteria.html (accessed December 2010).

Erdsieck, Peter, and Ruud van Herpen. Bepalen van interne warmtelast. Delft: Kennisbank Bouwfysica TU Delft, 2005.

European Commission. Air Quality Standards. 2010. http://ec.europa.eu/environment/air/quality/standards.htm (accessed December 2010).

Fjeld, T. “The Effect of Indoor Foliage Plants on Health and Discomfort Symptoms among Office Workers.” Indoor Built Environ, 1998, 7; p204-209 ed.

Gates, D.M. “Transpiration ratesand temperatures of leaves in cool humid environment.” J. Arnold Arboretum Harvard University 50, 1969: 93-98.

Gerhardt, Clara, and Brenda Vale. Comparison of resource use and environmental performance of green walls with façade greenings and extensive green roofs. Victoria: School of Architecture Victoria, 2010.

“Green living walls.” Go Green, 2009.

Greene, Ben. The farmery. 2009. http://thefarmery.com/ ( accessed November 2010).

Hegger, Fuchs, Stark. Energy manual. Basel: Birkhauser, 2008.

Herpen, Ruud van. Gebouw en klimaatinstallaties, Klimatiseringsconcepten inleiding. Delft: Kennisbank Bouwfysica, 2004.

Hunk Design. Green facade design. 2009. http://www.greenfacadedesign.com cleanair.html (accessed October 2010).

IUCN. Extinction crisis continues apace. November 2009. http://www.iucn.org/ ?4143/Extinction-crisis-continues-apace (accessed April 2011).

Johnston, Jacklyn, and John Newton. Building GreenA guide to using plants on roofs, walls and pavements. London: Greater London Authority, 2004.

Kennisbank Bouwfysica, Stichting. Tabellarium akoestiek en geluid. Delft: TU Delft, 2009.

Kravcík, M., J. Pokorný, J. Kohutiar, M. Kovác, and E. Tóth. Water for the Recovery of the Climate - A New Water paradigm. Slovakia: People and water NGO, 2007.

Page 103: Living Facades

101

Krusche, P, M Krusche, D Althaus, and I Gabriel. Okologisch bauen. Berlin: Bauverlag, 1982.

Lesiuk, Stephen. “Plant building interaction.” Dept of Architecture, 2000.

Livingwall pdf. 2004. http://www.watgreen.uwaterloo.ca/projects/library/ f02livingwall.pdf (accessed juni 2010).

McCabe, Ed. O2xygen therapies. Energy Publishers, 1988.

Moinat, Arthur D. “Available Water and the Wilting of Plants.” Plant Physiology, no. Vo. 7, No. 1 (January 1932): 35-46.

Moll, Gary, and Stanley Young. Tree Facts: growing greener cities. Venice: Living planet press, 1992.

Morales, Dominic J. “The contribution of trees to residential property value.” Journal of Arboriculture (Journal of Arboriculture), 1980: 305.

NASA. making of Urban heat island. 2009. http://earthobservatory.nasa.gov/ Features/GreenRoof/greenroof2.php (accessed 2010).

—. Surface meteorology and Solar Energy. 2010. http://eosweb.larc.nasa.gov/sse/.

National Weather Service. Climatological data. August 2010. http://www.erh. noaa.gov/okx/climate_cms.html (accessed November 2010).

New York City regional heat island initiative. “Mitigating New York City’s Heat Island with Urban Forestry, Living Roofs, and Light Surfaces.” 2006.

New York Energy Portal. 2005. http://www.eredux.com/states/state_detail php?id=1113 (accessed November 4, 2010).

New York news and features. April 2007. http://nymag.com/news features/30020/index2.html (accessed Oktober 2010).

New York State Biodiversity Project. Birds of New York State. New York State Biodiversity Research Institute. 2001. http://www.nybiodiversity.org summaries/birds/species.html.

Newton, Johnston &. Building Green. London: Greater London Authority, 2004.

Nowak, D.J., and R.A. Rowntree. Atmospheric carbon dioxide reduction. General Technical Report NE-186, Northeastern Forest Experiment Station: United States Department of Agriculture, 1994, 83-94.Owen, P.J. Influence of botanic garden experience on human health (Master thesis). Manhattan: Kansas State University, Department of Horticulture, Forestry and Recreation Resources, 1994.

Page 104: Living Facades

102

Praag, Roby van. Groen moet je doen; de effecten van groen gebruiken in de bouw om het leefklimaat van de mens te verbeteren. Delft: Delft University of Technology, 2011.

Robinson, S. J. and Schmidt, J. T. “Fluorescent Penetrant Sensitivity and Removability.” Materials Evaluation, 1984: 1029-1034.

Louis Le Roy, life and work in time and space. Directed by Beate Lendt. Performed by Louis le Roy. 2010.

Schenk, George. Moss Gardening. Cambridge: Timberpress, 2004.

Schildwacht, Van de Wetering, Schoenmaker. “Lucht zuiveren met groen luistert nauw.” Tuin en Landschap, December 2008: 30-32.

Schmidt, Marco. The contribution of rainwater harvesting against global warming. Berlin: Technische Universität Berlin, 2006.

Schundler. Plant guide - Biofiltration. 2010. http://www.schundler.com/ biofiltration.htm (accessed November 6, 2010).

Skillings, Pamela. Bedbugs Invade New York. 2010. http://manhattan.about.com od/citylife1/a/bedbugsbites.htm (accessed 2010).

“Sky’s the limit.” DIMAG, 2009: 36-43.

Stec, W.J., A.H.C. van Paassen, and A. Maziarz. “Modelling the double skin facade with plants.” Energy and Buildings 2005, no. 37 (2004): 419-427.

Sustainability and business. 2008. http://www.sas.com/news/sascom/2008q2 feature_sustainability.html (accessed juni 2010).

Swyngedouw, Kaika, and Heynen. In the nature of cities. Londen; New York: Taylor & Francis, 2006.

TEEB. The Economics of Ecosystems and Biodiversity for Local and Regional Policy Makers. New York: United Nations Environment Programme, 2010.

Tukiainen, Matti. Gaisma. 2005. http://www.gaisma.com/en/location/new-york ny.html (accessed December 2010).

Ulrich, R.S., Simons, R.F., Losito, B.D., et al. “Stress recovery during exposure to natural and urban environments.” Journal of Environmental Psychology, 1991, 11; p201-230 ed.

UNDP. Beyond scarcity: Power, poverty and the global water crisis. New York: United Nations Development Programme, 2006.

UNEP & UN Habitat. Eco systems and biodiversity: the role of cities. New York: United Nations, 2005.

Page 105: Living Facades

103

United Nations University. “Desertification: Experts Prescribe Global Policy Overhaul to Avoid Looming Mass Migrations.” United nations university. June 2007. http://archive.unu.edu/media/archives/2007/files/mre29-A- 07.pdf (accessed April 2011).

Urban Heat Islands and Climate Change. The University of Melbourne. November 2006. http://www.earthsci.unimelb.edu.au/~jon/WWW/uhi-melb.html (accessed june 2010).

US naval observatory. Sun or Moon Altitude/Azimuth Table: U.S. Cities and Towns. 2011. http://www.usno.navy.mil/USNO/astronomical- applications/data-services/alt-az-us (accessed maart 2011).

Van der Linden, A.C. Zonnestraling en zonstralingsgevens. Delft: Kennisbank bouwfysica, 2005.

VEJA. Februari 2009. http://www.veja.it/?p=4812 (accessed September 2010).

Warburg, Otto H. The prime cause and prevention of cancer. Lindau, 1966.

Wener, Peter, and Rudolf Zahner. Biological diversity and cities. Leipzig: Bundesamt für Naturschutz (BfN), 2009.

White, Ian. “Biologymad resources.” Biologymad.com. april 2006. http://www. biologymad.com/resources/RevisionM5Ch5.pdf (accessed september 2010).

Wikipedia. Leaf shape. 2010. (accessed December 2010).

Wilson, Edward O. Biophilia. Cambridge: Harvard University Press, 1984.

Wittig, Rudiger. The origin and development of the urban flora of central Europe. Frankfurt: Wolfgang Goethe Universitat, 2004.

Wong, Nyuk Hien. Evaluation of vertical greenery systems for building walls. Singapore: National University of Singapore, 2009.

Wong, Nyuk Hien, and Alex Yong Kwang Tana. “Acoustics evaluation of vertical greenery systems for building walls.” Building and Environment (Department of Building, School of Design and Environment, National University of Singapore) Volume 45, no. Issue 2 (Februari 2010): 411-420.

Wong, Nyuk Hien, et al. Thermal evaluation of vertical greenery systems for building walls. Singapore: Building and Environment, National University of Singapore, 2009.

Zimmermann, A. Constructing Landscape. Basel: Birkhauser, 2008.

Page 106: Living Facades

104

Page 107: Living Facades

105

pictures, diagrams and tablesItems that are not mentioned in this list are made specifically and exclusively for this project by the author, Roel Rutgers.

Figure 2.3: Jean Nouvel. “Louvre Museum Abi Dhabi”. September 2010. http://www.eikongraphia.com/wordpress/wp-content/Jean%20Nouvel%20Louvre%20Museum%20Abi%20Dhabi%20%281%29.jpg (accessed 2010)

Figure 2.5: Wildlife conservation society. “Map of human footprint”. 2002. http://www.ciesin.columbia.edu/wild_areas/ (accessed 2010)

Figure 2.6: Le Roy, L.G. “Eco-cathedral”. 2008. http://www.ecokathedraal.nl/ (accessed 2010)

Figure 3.2: G-sky. “Living wall systems”. 2009.http://www.impactlab.net/wp-content/uploads/2009/05/g-sky2.jpg (accessed 2010)

Figure 3.3: ELT. “Living wall systems”. 2009.http://www.impactlab.net/wp-content/uploads/2009/05/g-sky2.jpg (accessed 2010)

Figure 3.4: ELT. “ELT New and Improved Living wall panel”. 2010.http://elteasygreen.myshopify.com/blogs/news (accessed 2010)

Figure 3.5: Aurora Mahassine. “Habitile”. 2011.http://media.tripod.lycos.com/preview/1845836/1024x1024-1860476.jpg (accessed 2011)

Figure 3.6: Mosstika. “Living wall”. 2009.http://www.dsgnwrld.com/wp-content/uploads/succulent-living-wall-brooklyn-green-spaces-mosstika-5.jpg (accessed 2011)

Figure 3.7: Bakker, J. “Schiavello Vertical Garden”. 2008.http://inhabitat.com/files/schiavellovg1.jpg (accessed 2011)

Figure 3.8: Venhoeven CS. “Wonderwall”. Gevel totaal beurs. 2007.

Figure 3.7: Venhoeven CS. “Sportplaza Mercator”. Dax Magazine Volume 10, 2007.http://www.dax-magazine.nl/nws/show_item.php?id=14042500 (accessed 2010)

Figure 3.10: Greenworks design. “Self-watering-green-wall”. 2009. http://designcrave.com/2009-05-22/bring-a-self-watering-green-wall-into-your-office/ (accessed 2010)

Figure 3.11: C. Loidl-Reisch. “Inner courtyard planting”. Zimmermann, A: Constructing Landscape. Basel: Birkhauser, 2008.

Page 108: Living Facades

106

Figure 3.12: Jacob’s green solutions. “Sihl city”. 2008. http://www.building.co.uk/pictures/458xAny/4/4/9/1611449_sihlcity3crop.jpg (accessed 2010)

Figure 3.13: BBC Gardening. “Hedera Helix” 2006.http://www.bbc.co.uk/gardening/plants/plant_finder/images/large_db_pics/large/hedera_helix.jpg (accessed 2010)

Figure 3.14: SXC. “Moss on concrete”. 2007. http://www.sxc.hu/pic/m/d/dl/dlritter/736669_moss_on_concrete.jpg (accessed 2010)

Figure 3.15: Wikispaces. “Revetment”. 2005.http://ih-igcse-geography.wikispaces.com/file/view/1.9C_Gabions.png/80224243/1.9C_Gabions.png (accessed 2010)

Figure 3.16: Betafence. “Steenvulling”. 2006.http://www.gabionsolutions.com/documents/nieuwe-website-fe-30-10-2008/steenvulling/3-grijze-breuksteen.jpg (accessed 2010)

Figure 4.1: Arup Engineers. “Vertically Integrated Greenhouse”. 2009.http://www.cityfarmer.info/wp-content/uploads/2009/12/strawberryvertical.jpg (accessed 2010)

Figure 4.2: Stuurlui Stedenbouw & Atelier GRAS!. 2010.http://inhabitat.com/wp-content/blogs.dir/1/files/2010/12/eathouse-ed01-537x410.jpg (accessed 2011)

Figure 4.3: Urban Garden Magazine. “Chef John Mooney”. 2010.http://urbangardenmagazine.com/wp-content/uploads/2010/08/Z-Chef-John-Mooney-10-700x523.jpg (accessed 2011)

Figure 4.4: Hegger, Fuchs, Stark, Zeumer. “The energy manual”. Basel: Birkhauser, 2008; P.76

Figure 4.5: Wikimedia commons. “Air Pollution-Causes & Effects”. 2009. http://en.wikipedia.org/wiki/File:Air_Pollution-Causes%26Effects.svg (accessed 2010)

Figure 4.6: Bruse, Thönnessen, Radtke. “Figure 1: Leaf stripped with Polyvinyl-Butyrales (left), uncleaned leaf surfaces, June (middle) and October (right)”; Practical and theoretical investigation of the influence of Facade greening on the distribution of heavy metals in urban Streets, Cologne: 2003; p2.

Figure 4.7: NYC Health. “Figure PM-4: Map of estimated PM2.5 concentrations, winter 2008-2009”; The New York City Community Air Survey, New York: 2009; p15

Page 109: Living Facades

107

Figure 4.8: NYC Health. “Figure SO2-4: Map of estimated SO2 concentrations, winter 2008-2009”; The New York City Community Air Survey, New York: 2009; p21

Figure 4.9: NYC Health. “Figure NO2-4: Map of estimated NO2 concentrations, winter 2008-2009”; The New York City Community Air Survey, New York: 2009; p19Figure 4.10: Wikimedia Commons. “Simple photosynthesis overview”. 2008.http://en.wikipedia.org/wiki/File:Simple_photosynthesis_overview.svg (accessed 2010)

Figure 4.11-1: AHA Horeca Meubilair. “Ficus Benjamina”. 2005. http://www.altijdhandig.com/files/ficus-benjamina[1][1].jpg (accessed 2011)Figure 4.11-2: Indoor plants online. “Kentia”. Sd.http://www.indoor-plants.co.uk/kentia2.jpg (accessed 2011)Figure 4.11-3: Greens by white inc. “Dracaena fragrans ‘Massange” sd.http://zoldvilag.info/sites/default/files/gallery_assist/1/gallery_assist49/prev/Dracaena_fragrans__Massange.jpg (accessed 2011)Figure 4.11-4: Bijoukaleidoscope. “The Peace Lily Spathyphyllum wallisii”. 2009. http://www.paperbean.com.au/blog/pic_spati_medium.jpg (accessed 2011)Figure 4.11-5: Amienne. “Dracaena marginata”. 2008.http://amienne.files.wordpress.com/2008/04/marginata.jpg (accessed 2011)Figure 4.11-6: Indoor plants online. “Philodendron Scandens”. Sd.http://www.indoor-plants.co.uk/trebie.jpg (accessed 2011)Figure 4.11-7: May’s Floral Garden. “Scheff. Arboricola”. 2009.http://www.maysfloralgarden.com/files/plants/images/scheffleraarboricola.jpg (accessed 2011)

Figure 4.12: Wong, Nyuk Hien, et al. “Fig. 2. Acoustics experiment setup in HortPark”; Thermal evaluation of vertical greenery systems for building walls. Singapore: Building and Environment, National University of Singapore, 2009.p. 413

Figure 4.14: Wong, Nyuk Hien, et al. “Fig. 7. Average insertion loss for the entire eight vertical greenery systems during the acoustics experiments in HortPark”; Thermal evaluation of vertical greenery systems for building walls. Singapore: Building and Environment, National University of Singapore, 2009.p. 416

Figure 4.15: Wong, Nyuk Hien, et al. “Fig. 3. Dimensions of vertical greenery system inside reverberation chamber”; Thermal evaluation of vertical greenery systems for building walls. Singapore: Building and Environment, National University of Singapore, 2009.p. 414

Figure 4.16: Wong, Nyuk Hien, et al. “Fig. 10. Average reverberation times (T30); Fig. 12. Sound absorption coefficients of vertical greenery system and other building materials”; Thermal evaluation of vertical greenery systems for building walls. Singapore: Building and Environment, National University of Singapore, 2009.p. 418

Page 110: Living Facades

108

Figure 4.17: Van Praag, R. “Figuur 5.11: Houten wand; Figuur 5.13: Aluminium wand”; Groen moet je doen. Delft: Faculteit Bouwkunde TU Delft, 2011. P. 54

Figure 4.18: Van Praag, R. “Figuur 10: Plattegrond meetruimte schaal 1:100”; Groen moet je doen. Delft: Faculteit Bouwkunde TU Delft, 2011. P. 51

Figure 4.20: New York State Biodiversity Project . “Figure 1. A depiction of the expected species variety (richness) of breeding birds across New York State”. 2001. http://www.nybiodiversity.org/summaries/birds/images/figure1sm.gif (accessed 2010)

Figure 4.21: Zazzle. “Heldere rode bessenboom in Skagway Alaska”. 2006.http://rlv.zcache.com/red_berry_tree_in_skagway_alaska_postcard-p239574489439198016z8iat_400.jpg (accessed 2011)Figure 4.22: Florida State Parks. “Tree frog on leaf”. 2003.http://www.floridastateparks.org/rockspringsrun/img/photogallery/rsr-treefrogonleaf-park.jpg (accessed 2011)

Figure 4.23: Hyperphysics. “The Color-Sensitive Cones”. 2010.http://hyperphysics.phy-astr.gsu.edu/hbase/vision/imgvis/colcon.gif (accessed 2011)

Figure 4.24: University of Basel. “Eye sensitivity”. 2011.http://miac.unibas.ch/SIP/02-Fundamentals-media/figs/eyeSensitivity.png (accessed 2011)

Figure 4.25: USGS. “Water cycle”. 2005.http://upload.wikimedia.org/wikipedia/commons/9/94/Water_cycle.png (accessed 2011)

Figure 4.26: Kravcík, M., J. Pokorný, J. Kohutiar, M. Kovác, and E. Tóth. “Fig. 1 The large and small water cycles on land”; Water for the Recovery of the Climate - A New Water paradigm. Slovakia: People and water NGO, 2007. P.20

Figure 4.27: Schmidt, Marco. “Fig. 3 Annual energy conversion via evaporation in comparison to the solar radiation and world energy consumption”; The contribution of rainwater harvesting against global warming. Berlin: Technische Universität Berlin, 2006. P.3

Figure 4.28: Emerald Cities Initiative. “Urban Heat Island Effect”http://www.emeraldcitiesproject.com/emeraldcities-initiative/images/stories/heat-island%2072dpi.jpg (accessed 2010)

Figure 4.29, 4.30, 4.31: NASA Earth Observatory. “Gaffin” 2002. http://earthobservatory.nasa.gov/Features/GreenRoof/greenroof2.php (accessed 2011)

Figure 5.3: SCM waterproof porous “Evapotranspiration”. 2011 http://scmwaterproofporous.blogspot.com/2011/01/evapotranspiration.html (accessed 2011)

Page 111: Living Facades

109

Figure 5.9: Van der Linden, Kurvers, Raue, Boerstra, “Figure 2: Type Beta building/climate”; Indoor climate guidelines in The Netherlands: Developments towards adaptive thermal comfort. 2007: Construction Innovation: Information, Process, Management, Vol. 7 Iss: 1, pp.72 – 84

Figure 5.10: Van der Linden, Kurvers, Raue, Boerstra, “Figure 4: Type Alpha building/climate”; Indoor climate guidelines in The Netherlands: Developments towards adaptive thermal comfort. 2007: Construction Innovation: Information, Process, Management, Vol. 7 Iss: 1, pp.72 – 84

Figure 6.6: Raymond Bianchi. “America is a Different Place”. 2011. http://irasciblepoet.blogspot.com/2011/09/after-911-america-is-different-place.html (accessed 2011)

Figure 6.9: Carlstahl. “Façade Greenery”; Green Wall Systems. Süßen: 2008. p2

Figure 6.12: Gabriel treeservices. “Irrigation Management”. 2011. http://gabrieltreeservices.com/images/Pictures/Irrigation%20Management.jpg (accessed 2011)

Figure 6.14: Sissy Ziech. “Paised beds”. 2011. http://i891.photobucket.com/albums/ac112/chrissiebht/Textures/garden_soil_lg.jpg (accessed 2011)

Figure 6.15: Etsy. “Felts”. sd.http://ny-image3.etsy.com/il_fullxfull.78075654.jpg (accessed 2011)

Figure 7.2: Abhat, A. “Fig. 3. Latent heat of fusion per unit mass and per unit volume of selected phase change heat storage materials”; Low temperature latent heat thermal energy storage: heat storage materials. 1983: Solar Energy Vol 10, No. 4. pp 336.

Figure 7.3: NYC Swim. “Water temp graph for a full year”. 2005.http://www.nycswim.org/img/noaa_2005_water_temp_battery.gif (accessed 2011)

Page 112: Living Facades

110

appendices

A. Building systems Hort Park, SingaporeB. Leaf characteristicsC. Building VolumesD. Climate calculation modelE. Façade details

Page 113: Living Facades

111

A. Building systems Hort Park, Singapore

Description of vertical greenery systems in Hort Park. (Wong en Tana, Acoustics evaluation of vertical greenery systems for building walls 2010) Nr. System typology Description Plant size 1

2

3

4

5

6

7

7a

8

Living wall – Modular panel, vertical interface, mixed substrate

Green façade – Modular trellis

Living wall – Grid and modular, vertical interface, mixed substrate

Living wall – Modular panel, vertical interface, inorganic substrate

Living wall – Planter panel, angled interface, green roof substrate

Living wall – Framed mini planters, horizontal interface, soil substrate

Living wall – Vertical moss-tile, vertical interface, inorganic substrate

Living wall – Flexible mat tapestry, horizontal interface, soil substrate

Living wall – Plant cassette, horizontal interface, soil substrate

Versicell-based and ‘plug-in’ slot planter system with drainage cells with selected mixture of green roof and soil planting media wrapped in geo-textile membrane while the slotted planters are mainly planter cages system.

Climber plants in planters forming green screens across mesh panels on the wall.

Plant panels embedded within stainless steel mesh panels inserted into fitting frames.

Employed the Parabienta system with composite peat moss as a planting media inlay that is encased in a stainless steel cage and hung onto supports lined with integrated irrigation.

This system uses a UV-treated plastic as a moulded base panel with integrated horizontal planting bays.

Individual mini planters placed and secured onto stainless steel frame.

Patented ceramic tiles shipped with pre-grown moss species. Suitable for creating tiling designs

Lightweight panel comprising 2 layers of moisture retention mats secured onto a supporting grating or mesh. Plants slotted and pre-grown in between mats. Suitable for flat and curved surfaces. Allows easy change.

Use of planters to hold wider variety of plant types and of larger sizes. Planters are secured onto the wall by hinges. Lightweight growing medium is used.

Small to medium

Climber plants Small

Small

Small

Small

Small,

custom-grown on tiles

Small to medium

Small to medium-large

Page 114: Living Facades

112

Pictures of the eight systems. Above left to right systems 1-4 and below 5, 6, 7a and 8.

Page 115: Living Facades

113

B. Leaf characteristics

Leaf shape:

Leaf disposition:

Page 116: Living Facades

114

Leaf margin:

Source: (Wikipedia 2010)

Page 117: Living Facades

115

C. Building volumesThe defined shapes A to E are made into volumes by an extrusion of 100m. This results in five different volumes. Below a table with their quantities is given.

The section of each shape approximates 1000m2. This results in volumes of about 100.000m3 , which represents the volume of the UN Headquarters for Sustainability. All the other properties are given in the table below:

A B C D E width: 32 18 55 radius: 25 lower width: 50 m

height: 32 55 18 depth: 100 upper width: 22,5 mdepth: 100 100 100 height: 27,5 m

depth: 100 m angle: 63,4 °

volume: 102400 99000 99000 98175 volume: 99687,5 m3

surface area: 3200 1800 5500 5000 surface area: 5000 m2

South façade: 3200 5500 1800 Function of sun 3074,6 m2

end façade: 1024 990 990 982 996,9 m2

roof: 3200 1800 5500 7854 2250 m2

total: 11648 14780 11080 9817 10392,9 m2

The building shapes A, B & C are all calculated in the same way. Their volume V=height*width*depth; the surface area A=depth*width; the South façade S=depth*height; the end façade E=width*height; the roof R=A.

For shape D the surface area A=2*radius*depth; the end façade E=1/2 * π * radius2; the volume V=100*E; the roof R=π*radius*depth.

For shape E the angle between the surface area and the angular South façade α=tan(height/((1/2)*( lower width- upper width))); the surface area A=lower width*depth; the south façade S=(height/sin α)*depth; the volume V=S*depth; the roof R=upper width*depth.

Page 118: Living Facades

116

D. Climate calculation modelThe Excel model used for the calculation of the interior climate is displayed below. For the building quantities in the model the characteristics of the building volumes from Appendix C are used.

parameters:

Building users: 600 personsheat (Q): 80 Wlighting: 4000 m2

heat (q): 10 W/m2 equipment: 600 computers

heat (Q): 120 Wthermal area (A): 10000 m2

Glass heat transfer coeffient (U): 1,62 W/m2KZTA: 0,6LTA: 0,75

Concrete specific heat (c): 840 J/kg Kdensity (ρ): 2500 kg/m3

heat transiton coefficient (α): 8 W/m2 Kabsorption coefficient (αabs): 0,8

morning temp. (Tconcrete): 21 °C

Air min.-comfort winter: 20,3 °Cmax.-comfort winter: 22,8 °Cmin.-comfort zomer: 20,3 °Cmax.-comfort zomer: 25,5 °C

ventilation: 30 m3/hourspecific heat (c): 1,005 kJ/kg K

density (ρ): 1,2 kg/m3 morning indoor temp. (Tin): 21 °C

Plants max temperature difference: 3 °Cliving façade: 0,35 part

shade summer: 0,6 partopen summer: 0,05 partshade winter: 0,2 partopen winter: 0,45 part

heat transfer coefficient (U): 0,3 W/m2KLAI: 1

Ventilation summer 15 °Ctemperature winter 10 °C

Page 119: Living Facades

117

Solar radiation and outdoor temerature:

hour h qnormal Tout QH QV β qA S5:00 5,3 129 20,4 11,9 128,4 21,3 120,2 2730,96:00 15,7 327 22 88,5 314,8 10,9 321,1 3176,57:00 26,8 624 23 281,3 557,0 -0,2 624,0 3627,28:00 38,1 732 24 451,7 576,0 -11,5 717,2 4042,69:00 49,3 798 25 605,0 520,4 -22,7 736,0 4395,3

10:00 60,1 838 26 726,5 417,7 -33,5 698,5 4667,211:00 69 862 27 804,7 308,9 -42,4 636,2 4834,012:00 72,6 874 28 834,0 261,4 -46,0 606,7 4885,613:00 68 876 29 812,2 328,2 -41,4 656,7 4818,014:00 58,8 867 28,5 741,6 449,1 -32,2 733,4 4638,415:00 47,9 848 28 629,2 568,5 -21,3 789,9 4354,916:00 36,6 813 27,5 484,7 652,7 -10,0 800,6 3990,617:00 25,3 758 27 323,9 685,3 1,3 757,8 3568,418:00 14,3 665 26,5 164,3 644,4 12,3 649,8 3117,519:00 4 506 26 35,3 504,8 22,6 467,3 2674,4

9:00 14,8 10 -3 2,6 9,7 11,8 9,8 3138,610:00 21,1 324 -1,5 116,6 302,3 5,5 322,5 3400,011:00 25 507 0 214,3 459,5 1,6 506,8 3556,512:00 26 587 1,5 257,3 527,6 0,6 587,0 3595,913:00 24 597 3,3 242,8 545,4 2,6 596,4 3516,814:00 19,3 544 3 179,8 513,4 7,3 539,6 3326,315:00 12,4 401 2,5 86,1 391,6 14,2 388,8 3036,816:00 4 117 2 8,2 116,7 22,6 108,0 2674,4

Page 120: Living Facades

118

Page 121: Living Facades

119

Building shape A:

Page 122: Living Facades

120

Page 123: Living Facades

121121121

Building shape B:

Page 124: Living Facades

122

Page 125: Living Facades

123

Building shape C:

Page 126: Living Facades

124

Page 127: Living Facades

125

Building shape D:

Page 128: Living Facades

126

Page 129: Living Facades

127

Building shape E:

Page 130: Living Facades

128

Page 131: Living Facades

129

E. Façade detailsThis appendix contains 1:10 details of the façade for the modular green container system and the industrial felts system. The last four details are modulations of the standard detailing in order to meet the requirements from the sustainable properties of the plants better.

Page 132: Living Facades

130

Page 133: Living Facades

131

modular green containerPhase 1 - Horizontal

A4, scale 1:10

Page 134: Living Facades

132

Page 135: Living Facades

133

modular green containerPhase 1 - Angular

A4, scale 1:10

Page 136: Living Facades

134

Page 137: Living Facades

135

modular green containerPhase 1 - Arched

A4, scale 1:10

Page 138: Living Facades

136

Page 139: Living Facades

137

modular green containerPhase 1 - Vertical

A4, scale 1:10

Page 140: Living Facades

138

Page 141: Living Facades

139

industrial feltsPhase 1 - Horizontal

A4, scale 1:10

Page 142: Living Facades

140

Page 143: Living Facades

141

industrial feltsPhase 1 - Angular

A4, scale 1:10

Page 144: Living Facades

142

Page 145: Living Facades

143

industrial feltsPhase 1 - Arched

A4, scale 1:10

Page 146: Living Facades

144

Page 147: Living Facades

145

industrial feltsPhase 1 - Vertical

A4, scale 1:10

Page 148: Living Facades

146

Page 149: Living Facades

147

modular green containerPhase 2 - Horizontal

A4, scale 1:10

Page 150: Living Facades

148

Page 151: Living Facades

149

modular green containerPhase 2 - Angular

A4, scale 1:10

Page 152: Living Facades

150

Page 153: Living Facades

151

industrial feltsPhase 2 - Horizontal

A4, scale 1:10

Page 154: Living Facades

152

Page 155: Living Facades

153

industrial feltsPhase 2 - Angular

A4, scale 1:10

Page 156: Living Facades

154

Page 157: Living Facades

155

F. Final designThis appendix contains drawings of the final design.

Page 158: Living Facades

156

section & south facadeA4, scale 1:1000

Page 159: Living Facades

157

locationA4, scale 1:2000

n

Page 160: Living Facades

158

section & West facadeA4, scale 1:1000

Page 161: Living Facades

159

fragmentA4, scale 1:50

Page 162: Living Facades

160

detailsA4, scale 1:5