IN DEGREE PROJECT THE BUILT ENVIRONMENT,SECOND CYCLE, 30 CREDITS

, STOCKHOLM SWEDEN 2020

Studying building behaviors by using the Building Management System of a new teaching building

A study case of a school building in Stockholm

KAIYING ZHANG

KTH ROYAL INSTITUTE OF TECHNOLOGYSCHOOL OF ARCHITECTURE AND THE BUILT ENVIRONMENT

Studying building behaviors by using the

Building Management System of a new

teaching building

A study case of a school building in Stockholm

Kaiying Zhang

Thesis for the degree of Master of Science (MSc) at the Royal Institute of

Technology, Stockholm

Supervisor: Folke Björk

Examiner: Kjartan Gudmundsson

June 2020

i

Acknowledgement

I would like to express my deep and sincere gratefulness to my supervisor Professor Folke Björk from

KTH Royal Institute of Technology who lead me to such brilliant research and introduce an interesting

study case. Thank you for the support, advice, and inspiration throughout the degree project and for

introducing me to people who also helped a lot with this thesis.

I also would like to thank Sven Lindahl from Akademiska Hus for providing extensive and valuable

information about the building management system of the building. He spent a lot of time on the building

and system and gave advice and explanation. The completion of the thesis could not have been

accomplished without his help and guidance.

A special thanks to KTH and Akademiska Hus for offering this great study case and platform enabling

me to explore the indoor climate and building performance.

Last but not least, I would like to express my gratitude to my family and friends for supporting and

loving me all the time. I’m thankful for their care and encouragement throughout my master's program

study.

ii

Abstract

Building management system (BMS) offers a wide range of measurements and historical data about the

building but few types of researches use these data to analyze the building performance. This study aims

to explore the indoor climate and building insulation by taking advantage of the BMS of the study case,

which 767 sensors are installed in the room and wall structures and the signal data are available at the

online web application. In addition, during the inspection, several error sensors and meters are detected

are discussed as feedback for the system.

It is concluded that the building management system is a good tool to study the building performance in

different aspects and the measurements from the sensors are helpful but need validation by conducting

a further field measurement in the building,

Keywords: Building management system (BMS), Building envelope, Indoor climate, Thermal comfort,

energy performance.

iii

Table of Contents

Acknowledgement .................................................................................................................................. i

Abstract .................................................................................................................................................. ii

1 Introduction .................................................................................................................................... 1

1.1 Background ............................................................................................................................. 1

1.1.1 Certification system ............................................................................................................. 1

1.1.2 Building management system .............................................................................................. 2

1.2 Aim of this work...................................................................................................................... 3

1.3 Scope and boundaries .............................................................................................................. 4

1.3.1 Scope and outline ................................................................................................................ 4

1.3.2 Assumption and boundaries ................................................................................................ 4

2 Literature review: Terminologies and concepts .......................................................................... 5

2.1 Building Insulation .................................................................................................................. 5

2.2 Indoor climates ........................................................................................................................ 6

2.2.1 Thermal Climate .................................................................................................................. 6

2.2.2 Indoor Air Quality (IAQ) .................................................................................................. 12

2.3 Energy consumption in buildings .......................................................................................... 13

3 The study case............................................................................................................................... 15

3.1 U-house ................................................................................................................................. 15

3.2 Platform: Styrportalen ........................................................................................................... 16

4 Method .......................................................................................................................................... 17

4.1 Styrportalen ........................................................................................................................... 17

4.2 Indoor environment assessment ............................................................................................ 19

4.2.1 Data from the sensors in the building envelope and weather station ................................ 19

4.2.2 CBE Thermal Comfort Tool .............................................................................................. 20

4.2.3 Ventilation systems ........................................................................................................... 21

4.3 Energy Analysis .................................................................................................................... 21

4.4 Interview, documents from Akademiska Hus ....................................................................... 22

5 Result ............................................................................................................................................. 23

iv

5.1 The control system ................................................................................................................ 23

5.2 Building behavior .................................................................................................................. 24

5.2.1 Interesting moments .......................................................................................................... 24

5.2.2 Building behavior in Cold days ......................................................................................... 27

5.2.3 Building behavior in warmer days .................................................................................... 41

5.3 Energy consumption .............................................................................................................. 48

6 Discussion ...................................................................................................................................... 50

6.1 Feedback and fault diagnosis ................................................................................................ 50

6.2 Future research and reflection ............................................................................................... 53

7 Conclusion..................................................................................................................................... 55

Reference .............................................................................................................................................. 56

1

1 Introduction

1.1 Background

World’s energy consumption in buildings is increasing every year and it occupies a share of 40% in the

total primary energy consumption in the US and EU (Cao, Dai, & Liu, 2016) which is above industry

and transport figures (Pérez-Lombard, Ortiz, & Pout, 2008). In the past, during the operation of the

building, up to 50% of the building energy consumption is consumed by the heating, ventilation, and

air-conditioning system. (Meir, Garb, Jiao, & Cicelsky, 2009) Today demand for high thermal comfort

with minimal energy consumption is a mission pursued by researchers and designers.

Buildings have different purposes serving human beings and people spend 90% of their time performing

activities in some specific indoor environment (USGBC, 2020). In order to maintain a proper building

indoor environment for the occupants, researches are concerned about the indoor environment quality

(IEQ). IEQ includes indoor air quality(IAQ), thermal comfort, lighting, acoustics, tap water, vibration,

and other aspects that affect human life inside a building (Mujeebu, 2019). Therefore, the occupants’

health and productivity are largely affected by IEQ (Fisk, 2002). Occupants exposed in buildings with

poor IEQ will lead to having building syndrome symptoms (SBS), such as headache, sore throat, and

loss of concentration (Lyles et al., 1991). For educational buildings, people spend years studying and

working in these buildings, and hence it is very important to inspect the IEQ of an educational building.

1.1.1 Certification system

To assess the quality of building environment and performance, encourage the design of a more

sustainable building, and motivate a future smart building technology, different green building

certifications and rating systems come into the building industry. There is a range of sound building

certification systems in the industry.

The WELL building standard is a third party performance-based system certified by the Green Business

Certification Incorporation (GBCI). It measures, monitors, and certifies the environment quality of the

building and sets requirements in terms of air, water, nourishment, light, fitness, comfort, and mind. It

focuses exclusively on the connection between building and the health or well-being of its occupants by

conducting massive medical researches and it is awarded at three levels, silver, gold, and platinum

(USGBC, 2020).

Leadership in Energy and Environment Design (LEED) is one of the international green building

certification program developed by the non-profit U.S. Green Building Council for worldwide

environmentally sound buildings. The program consists of several rating systems such as Building

Design & Construction (BD+C), Interior Design &Construction (ID+C), etc. for different building types

and construction phases (USGBC, 2020). To achieve the LEED certification, there are prerequisites and

credits to earn for the projects, and the more credits the project gained, the higher level of certification

it achieves (USGBC, 2020).

Swedish building certification systems are available such as the Miljöbyggnad. It measures 16 different

aspects by independent third parties. The indoor environment is the main area that the assessment focus.

The air quality, sufficient daylight according to the performance, Miljöbyggnad with different levels,

including bronze, silver, and gold, will be issued by the organization. To achieve a Miljöbyggnad gold,

the environment profile should be excellent with low energy cost and high comfort since the gold

2

standard is extremely high and even a survey about the users’ satisfaction of the building will be

conducted after the two-year operation (SGBC, 2020). It is a high demand for the designers and

constructors and building certified by this honor not only assure the sustainability of itself but also helps

improve the quality of the neighborhood.

There is evidence that a certified green building has a higher asset value because it has lower operational

expenses and higher occupants’ productivity (Al Horr et al., 2016). A survey of over 500 tenants who

worked in a LEED or Energy Star labeled building shows that green buildings reduce the absence rate,

increase occupant productivity and their wellness (Miller, Pogue, Gough, & Davis, 2009).

Overall, adopting a green building certification system is helpful to encourage a better future building

performance design that the building works safer, more effective, and economically. Constructors of the

certified green buildings can build the trust of their brand and meanwhile benefiting society (Nilsson,

2018).

1.1.2 Building management system

The development of the building automation system and cloud technology give a brand new method to

optimize the indoor building environment while saving the operation cost. A building management

system is a computer-based controller network installed in buildings for regulating and monitoring the

mechanical and electrical equipment of the building which is known as Building Automation Systems

(BAS) and Building Control System as well (Gjoko K., 2019). Most major buildings or facilities

implement BMS linked to the HVAC system, water circulation system, sprinkler system, and electrical

power, aiming to guarantee the safety operation while optimizing the building performance (Jagschies,

Lindskog, Lacki, & Galliher, 2018). Figure 1.1 shows an example of components controlled within a

BMS. BMS subsystems link the functionality of different equipment and hence they can work within

the integrated system (Gjoko K., 2019).

Figure 1.1 Components controlled within a BMS (Gjoko K., 2019)

3

The prime functionality of the BMS should be retained within the building environment, offering

malfunction alarms to the operator of the building, monitoring device disfunction, and performing

building-wide. Adapting BMS to the design of a building is necessary for achieving sustainability

(Hossain, 2018).

The study of BMS is prevalent in designing and controlling the building but researchers barely take

advantage of the wealth of data logged by the BMS (O’Sullivan, Keane, Kelliher, & Hitchcock, 2004).

As a result, BMS is not only an essential part of the building maintenance but also a tool for studying

the building performance by measuring the output of the control system. The study result can guide a

further improved operation of the building.

1.2 Aim of this work

Undervisningshuset (The U-house) which was built in 2017 is a relatively new building applied with

advanced technologies and it is well-known for its popularity among students and its unique design. Its

monitoring system is designed as a tool to explore the building and it is feasible for students in KTH to

access. Though there are some research studies done about this building, few researchers adopting the

system, using sensors installed in the building, accessing the data from these signals as a tool to acquire

information and measurements of the building condition. Therefore, this thesis aims to focus on the

building management system of the U-house, describing the sensors, the operating system, and through

this, investigating the building indoor climate by using the data from the sensor signals.

To be more specific, the thesis explains the detailed approach of using the online application

Styrportalen where the information in the BMS is available, to investigate the building and find useful

data, and demonstrates how it can be such a useful and unique tool for studying the building.

The energy consumption of a building has a connection with its envelope. It is necessary to check the

performance of the building envelope by using the BMS system of the building when designing new

buildings. (Hossain, 2018). Commonly the sensors in the structures are limited by the requirements,

discontinuous signals, and high cost(Hung, Chang, Hsu, & Chen, 2012) but the U-house has sensors

installed in the different layers in the building envelope and connected the signals to the BMS. Therefore,

the insulation inspection is available through Styrportalen.

The building environment responds to factors e.g. climates, occupants, etc. and is controlled by the

building management system, providing a dynamic environment for users to perform their daily work,

such as teaching, studying, and communicating with each other. This thesis also investigated the thermal

comfort, the indoor air quality, and the energy use of this building through the historical data from the

BMS.

There are 767 sensors installed in the buildings and the BMS keeps receiving and recording data from

the sensors and it is inevitable to have errors in some sensors and signals. In the thesis, the faults and

errors found through the historical data were reported and discussed. It is a feedback for the constructors

and designers, to make further improvement for the U-house and other construction.

Furthermore, most of the documents and drawings of this building are in Swedish and this thesis can be

a useful reference and guide for people who want to use the Styrportalen to study the building

environment.

4

1.3 Scope and boundaries

1.3.1 Scope and outline

First, a literature review was done for a basic overview of the terminology and theories about the

building insulation, building indoor environment, including the thermal comfort, indoor air quality

(IAQ), and energy consumption or office buildings.

The second part specifically introduced the study case, which is the U-house of KTH, the use of the

monitoring system, and its overview performance in terms of certification and energy declaration). The

platform that makes the building management system visible and accessible was introduced.

The methodology part showed the approach of using Styrportalen to access to the data from the sensors

with pictures illustration. It also described what kind of data and its source used to understand the

behavior of the building.

The result part showed the understanding of the building behavior and the assessment its performance.

Detailed inspections and measurements are provided by the sensors through Styrportalen and a range of

findings are demonstrated in this part, followed by the discussion, further analysis of some errors,

problems, and giving feedback to the control system of the building. At last, a conclusion was presented

with a summary of findings, measurements, and assessment.

1.3.2 Assumption and boundaries

The measurements of the building only came from the sensors visible in the system Styrportalen. There

are three levels of authority to access Styrportalen. In this thesis, it’s the KTH student level that can

check all the historical data of the building but cannot edit or control it through the system. The building

includes lecture rooms, group rooms which are fairly private spaces for studying and on the other hand,

in the open studying area, some sensors are not available because it is difficult to define the area and to

measure. Therefore in this thesis, only the rooms with clear boundaries are studied. The open area can

be measured by devices in the field in further study and applied the data in the system as assistance. The

study focuses on the most recent time period during the operation of the building, which is 2019 and

2020.

There are diverse data in many aspects of the building and therefore it is impossible to check and study

all of them. In the thesis, only part of the data was used to study the temperature changes in the building

façade, the thermal comfort, and IAQ of the related rooms. Some remaining sensors have not been

checked and used.

Some unpublished construction documents are obtained from Sven, the engineer of the Akademiska Hus

who was in charge of the control system of Undervisningshuset. All the documents available are in

Swedish since the building is constructed in Swede by Akademiska Hus. The translation of the

documents was helped by google translate.

The study only focuses on U-house and using its building management system and weather information

in Sweden, the Stockholm region. Only the operating time of the building, which excludes the summer

and winter holidays was taken into consideration and for occupants in the building, the KTH academic

schedule was applied. There are no field measurements in this thesis.

5

2 Literature review: Terminologies and concepts

2.1 Building Insulation

Thermal insulation is the process that the rate of heat transfer between objects in thermal contact is

reduced. This process involves a combination of materials with low thermal conductivity (Thermal

engineering, 2020). Proper thickness of insulation in the building envelope helps to reduce the heating

and cooling load of the building (Kaynakli, 2012). In addition, it can help cut down the CO2 and SO2

emissions into the atmosphere. A study shows that when the building applies an optimum insulation

thickness, the energy consumption was decreased by 46.6% and the emissions of CO2 and SO2 were

reduced by 41.53% (Dombaycı, 2007). As a result, the performance of the external façades of the

building is the key to the green building.

Thermal conductivity is the time rate of steady-state heat flow (W) through a unit area of 1m thick

homogeneous material in a direction perpendicular to isothermal planes, induced by one Kelvin

temperature difference across the sample. It measures the ability of a material to conduct heat (Al-

Homoud, 2005). The thermal conductivity of a type of material is uncertain and it is sensitive to the

density, porosity, moisture content, and operating temperature of the material. Studies show that the

thermal conductivity of the material becomes higher when its moisture content rises or when it is at a

higher operating mean temperature. The relative level of sensitivity to operating temperature for a group

of materials will vary regarding the considered density of the material (Abdou & Budaiwi, 2005). As

references, the thermal conductivity of air is 0.024 W/m-1 k-1 at 0 ℃ and 0.026 W/ m-1 k-1 at 25 ℃

(Thomas, 1993).

The most commonly used materials for building insulation are made from mineral wool such as glass

wool or rock wool and plastic foam such as polystyrene, which has the best performance per unit cost.

Therefore, these materials have the largest commerce potential for insulation material (Pavel &

Blagoeva, 2018). Figure 2.1 shows different types of materials used for building insulation in the market.

Figure 2.1 Types of material used in building thermal insulation (Pavel & Blagoeva, 2018)

6

Comparative case analysis on some commercial thermal insulation including Polyisocyanurate,

Polyurethane, stone wool, XPS, etc. concluded that the polyisocyanurate performs the best in aspects of

thermal transmittance with the thermal conductivity of 0.022 W/m-1 k-1. It has the most suitable material

for a cold climate while in warmer time, it is not the best choice due to its low density (Schiavoni,

Bianchi, & Asdrubali, 2016). Though the commercial materials are economical and effective, significant

environmental damage is caused by these materials during the production phase since the production

uses a large amount of fossil energy and non-renewable and they are also problematic in the disposal

phase that the material cannot be recycled (Asdrubali, D'Alessandro, & Schiavoni, 2015). There are

sustainable insulation materials made from renewable materials such as biopolymers but the price of the

new materials is high (Pavel & Blagoeva, 2018) and even some of them are not available in the market.

Therefore the insulation materials are still under development.

Generally, the building envelope is made up of different layers including the insulation and the structural

components such as the concrete junction, steel in openings (windows, doors), painting, and plaster. The

structure components may have high thermal conductivity, resulting in a heat loss and thermal bridges

and in the end, weaker insulation and larger energy consumption. Thermal bridge means an area in the

building envelope that has higher thermal transmission than the surrounding area of the walls, overall

leading to reduced performance of the thermal insulation of the building (Gorse, Johnston, & Pritchard,

2012). There are various types of thermal bridge occurred caused by different reasons such as the

geometric thermal bridges and structure thermal bridges and they exist in different types of building

(Nagy, 2014). To detect thermal bridges, either on-site with thermographic techniques or the numerical

simulation can be used and it is important for a high-insulation building to evaluate and avoid thermal

bridges for sustainability (Asdrubali, Baldinelli, & Bianchi, 2012).

2.2 Indoor climates

2.2.1 Thermal Climate

2.2.1.1 Heat exchange between body and environment

The heat transfers between the body and environment by means of conduction, convection, radiation,

evaporation. The process can be described by the heat balance equation,

𝑆 = 𝑀 − (±𝑊𝑘) ± (𝑅 + 𝐶) − 𝐸

[𝑊 ∙ 𝑚−2]

S is the rate of storage of body heat (+ for net gain); M is the rate of metabolic energy production

(always +); E is the rate of evaporative heat transfer (− for net loss); Wk is the rate of work (+ for work

against external forces, − for work eccentric or negative work); R is the rate of radiant heat exchange

(+ for a gain); C is the rate of convective heat transfer (+ for gain). (Gagge & Gonzalez, 2010)

2.2.1.2 Thermal Comfort

Thermal comfort means the state of mind that expresses satisfaction with the surrounding environment

and assessed by subjective evaluation (ASHRAE Standard 55, ISO 7730). The human body has different

sensations, cold, hot, or neutral in different indoor environments. Researches on thermal preference

concluded four types of thermal preferences for users, consistent directional preference, fluctuating

preference, high tolerance and sensitive to thermal changes, and high tolerance, not sensitive to thermal

7

changes (Shahzad, Calautit, Hughes, Satish, & Rijal, 2019). To maintain a comfortable thermal climate

for occupants, a well-designed HVAC (heating, ventilation, and air conditioning) system in the building

is required. As a result, enormous researches about thermal comfort are done to help design an ideal

indoor thermal climate for occupants.

There are six factors that affect the thermal comfort perceived by the human body.

Influencing factors

1. Air temperature

The air temperature, also known as dry-bulb temperature, is the average temperature of the air around

the human body with respect to location and time. It is measured by a dry-bulb thermometer which is

freely exposed to the air but shielded from radiation and moisture (Shah, Krueger, & Strand, 1994).

When measuring the air temperature, it should be careful to avoid the radiation of the heat source

(Standard & ISO, 1998).

2. Radiant temperature

Mean radiant temperature (MRT) is the uniform temperature of an imaginary enclosure in which the

radiant heat transfer from the human body (Standard & ISO, 1998). It is associated with the human body

and significantly influence the thermal comfort indexes such as predicted mean vote (PMV) (Poul O

Fanger, 1970) and therefore this factor is the most popular in human thermal comfort study (Chaudhuri,

Soh, Bose, Xie, & Li, 2016). It can be measured by a black globe thermometer or calculated according

to the measured values of the temperature, the sizes, and the distance to a person of the surrounding

surfaces (Standard & ISO, 1998).

3. Relative humidity

The relative humidity is the ratio between the actual amount of water vapor in humid air and the amount

of water vapor saturated in the air at the same temperature and pressure, usually expressed in percentage

(Standard & ISO, 1998).

People perceive hot or cold through the skin and the relative humidity can be detected as well. The

relative humidity affects the evaporation from the skin because the rate of evaporation is determined by

the ability to hold water vapor by the surrounding air and therefore has an influence on the thermal

comfort. High relative humidity decreases the effect of evaporation but an extremely dry environment

is harmful to the body as well (Balaras, Dascalaki, & Gaglia, 2007).

The recommendation of the relative humidity in the air-conditioned house is around 30% to 50%

depending on the times and seasons of the year (Housh, 2017).

4. Metabolic rate

The human body generates heat and it can be measure in the amount of energy and expressed by

metabolic rate. The metabolic rate depends on the activity level and the environmental conditions and

the unit of it is met which,

8

1 𝑚𝑒𝑡 = 58.2 𝑊/𝑚2

1 met energy is equal to the produced per unit surface area of an average person (1.8 m2) seated at rest

(ANSI/ASHRAE Standard 55-2010, 2013).

Table 2.1 Metabolic Rates for typical tasks (ANSI/ASHRAE Standard 55-2010, 2013)

5. Clothing insulation

The clothes that people wear can provide an effect of thermal insulation and protect the human body

from cold and outdoor pollutants. The insulation effect can be expressed in clo (Icl) units (ASHRAE,

2005)

1 𝑐𝑙𝑜 = 0.155𝐾 ∙ 𝑚2 ∙ 𝑊−1

9

1 clo amount of clothes can maintain thermal equilibrium for one person at rest in an environment at

21°C in a normally ventilated room (0.1 m/s air speed). Clothing insulation values for some typical

clothes are shown in Table 2.2.

Table 2.2 Clothing Insulation Values for Typical Ensemblesa (ANSI/ASHRAE Standard 55-2010,

2013)

6. Air movements

The rate of air movements at a point can be defined as the air speed or air velocity without considering

the direction. It affects the thermal sensation of the human body, slightly cooler, slightly warmer, or

neutral (Toftum, Melikov, Tynel, Bruzda, & Fanger, 2003). A high air speed may cause draught, an

undesired cooling of the human body caused by air movement (ASHRAE, 2005). It not only causes

discomfort but also implicated the indoor air quality and energy consumption (Povl Ole Fanger, Melikov,

Hanzawa, & Ring, 1988). Figure 2.2 shows the estimation of the air velocity required to offset the

temperature based on a theoretical calculation.

10

Figure 2.2 Air speed required to offset increased air and radiant temperature (ANSI/ASHRAE

Standard 55-2010, 2013)

The combined effect of the air velocity and temperature results in heat loss from the skin and to avoid

discomfort, ASHRAE Standard 55-2010 requires that for operative temperature above 25.5 ℃, the upper

limit of air velocity shall be 0.8m/s for an office building and for operative temperature below 22.5 ℃,

the limit shall be 0.15 m/s to prevent discomfort from draught. The recommended air velocity is below

0.25 m/s during the hot season and below 0.15 m/s during the cold season (ANSI/ASHRAE Standard

55-2010, 2013).

The operative temperature(t0) mentioned above, is “the uniform temperature of an enclosure in which

an occupant would exchange the same amount of heat by radiation plus convection as in the existing

non-uniform environment” (ANSI/ASHRAE Standard 55-2010, 2013). The calculation of operative

temperature is based on air temperature, mean radiant temperature (MRT), and air velocity (Dave, 2014).

In most practical cases where the relative air velocity no larger than 0.2 m/s or where the difference

between MRT and air temperature is smaller than 4 ℃, the operative temperature can be calculated with

sufficient approximation as the mean value of air and MRT (Standard & ISO, 1998).

The range of acceptable thermal comfort is according to the operative temperature instead of the dry-

bulb air temperature, which is shown in Figure 2.3.

Figure 2.3 Thermal Environmental Conditions for Human Occupancy (Moser, 2014)

11

Thermal Comfort model

When analyzing the thermal comfort, two main thermal comfort models are applied according to

different scenarios.

1. PMV/PPD

Based on the heat balance of the human body and empirical studies, P.O Fanger developed the

PMV/PPD method that is widely used as a tool to evaluate thermal comfort.

PMV is an index that predicts the mean value of votes of a larger group of persons on the thermal

sensation scale shown in Figure 2.4.

Figure 2.4 Seven-point thermal sensation scale (International Organization for Standardization, 2005)

It can be calculated with different inputs of the six influencing factors of thermal comfort but within

conditions should be satisfied where metabolic rate range from 0.8 met to 4 met, clothing insulation

from 0 clo to 2 clo, air temperature from 10 ℃ to 30 ℃, radiant temperature from 10℃ to 40 ℃, air

velocity from 0 m/s to 1m/s, water vapor partial pressure from 0 Pa to 2700 Pa (Poul O Fanger, 1970).

𝑃𝑀𝑉 = 𝑓(𝑇, 𝑀𝑅𝑇, 𝑅𝐻, 𝑣, 𝑐𝑙𝑜, 𝑚𝑒𝑡)

The PPD is an index that establishes a quantitative prediction of the percentage of thermal dissatisfied

people who feel too cool or too warm. The relationship between PMV and PPD is shown in Figure 2.5

and can be expressed by the following function according to ISO 7730: 2005.

𝑃𝑃𝐷 = 100 − 95 exp(−0.03353 ∙ 𝑃𝑀𝑉4 − 0.2179 ∙ 𝑃𝑀𝑉2)

Figure 2.5 PPD as a function of PMV (International Organization for Standardization, 2005)

12

As Figure 2.5 shows, the PPD value ranges from 5% to 100% and it is affected by the occupants’ position

in the room. According to ASHRAE Standard 55-2017, no occupied spots in the room could be over 20%

PPD (Guenther, 2019).

Nevertheless, the PMV/PPD model has not taken the adaptation mechanisms and outdoor environment

thermal conditions into consideration (Humphreys, Nicol, & Raja, 2007) and proved to has a low

prediction accuracy. As a result, the accuracy of PMV/PPD values is significantly influenced by the

ventilation, building types, and the climates (Cheung, Schiavon, Parkinson, Li, & Brager, 2019).

2. Adaptive comfort model

People are adaptive to different outdoor climate conditions during different times of the year and this

can affect the perception of indoor comfort. Differences in recent thermal experiences can change

people's thermal responses (ANSI/ASHRAE Standard 55-2010, 2013). The adaptive hypothesis predicts

that the thermal expectations and preferences of occupants in the building are affected by contextual

factors such as their recent thermal exposure history (de Dear & Brager, 1998). According to different

causes of adaption, there are basically three types of thermal adaptation, behavioral, physiological, and

psychological adaption.

The prevailing mean outdoor temperature as the input variable for the adaptive model was introduced

in the ASHRAE-55 2010 Standard and it only applies to the condition where outdoor climate conditions

can influence the indoor condition and the comfort. To be specific, buildings without mechanical cooling

can apply the adaptive model (ANSI/ASHRAE Standard 55-2010, 2013).

Thermal load

Thermal load is the heating or cooling energy demand to maintain the indoor temperature in the range

of setpoints. It depends on factors such as the ambient climate, the properties of the building envelope,

and the building’s relationship. As a result, the good performance of the building envelop can reduce the

thermal load and save energy costs (Widström, 2018).

2.2.2 Indoor Air Quality (IAQ)

The air in the building contains different chemicals and the quality of the indoor air has a significant

impact on occupants’ health and performance and hence it is an important indicator for the indoor

environment quality. Various contaminants in the air from a range of sources such as the outdoor,

building materials, and occupants themselves, release into the air and accumulate to a certain

concentration. The concentration of the pollutants is associated with the total volume of air in the room,

the rate of production, the rate of removal, the rate of air exchange with the outdoor environment, and

the outdoor pollutant concentration (Maroni, Seifert, & Lindvall, 1995).

Pollutants in the indoor air exist in different forms, gaseous pollutants, aerosols, odors, particles, and

radioactive matters. Gaseous pollutants such as carbon dioxide, nitrogen oxides, and ozone, volatile

organic compounds (VOCs) (Maroni et al., 1995). These pollutants are produced by the occupants or

from the outdoor environment, causing unpleasant feelings, irritants. It is worth to mention that the radon

gas and radon daughters generated by radioactive decay from water, some type of concrete or rocks in

the building can cause serious problems such as lung cancer (Jones, 1999). As a result, the contaminants

13

in the air should not exceed a certain level otherwise it may cause health problems which is known as

sick building syndrome (SBS), for example, headache, dizziness, asthma (Lyles et al., 1991).

Requirements are introduced and standards are set for insuring a livable and workable indoor

environment. Insufficient ventilation in the room may lead to a high concentration of pollutants and

therefore, the requirement worked as guidance for the HVAC system design and a standard for IAQ

assessment. The assessment of indoor air quality is necessary to avoid discomfort and health problem.

IAQ assessments normally can be conducted by measurements, calculation, or subjective votes.

Moreover, numerical simulation is more and more commonly used for IAQ assessment due to the

development of computer models (Sarbu & Sebarchievici, 2013).

When people have activities indoor, the oxygen is consumed and the carbon dioxide is produced by

occupants making the concentration of CO2 become higher. Therefore, the carbon dioxide concentration

is widely used as a surrogate indicator for assessing IAQ and ventilation efficiency(Hui, Wong, & Mui,

2008), according to the fact that people emit CO2 at a rate that depends on their body size and metabolic

level as well as the fact that the indoor CO2 can be used as a tracer gas when its concentration exceeds

the outdoor level(Persily, 1997). A certain amount of CO2 in indoor air can cause discomfort or even

health problems. Researchers used generalized estimating equation models and concluded that workers

exposed to indoor CO2 concentrations higher than 800 ppm were likely to report more eye irritation or

upper respiratory symptoms (Tsai, Lin, & Chan, 2012). CO2 concentrations in acceptable outdoor air

typically range from 300 to 500 ppm. The upper limit of carbon dioxide is 1000ppm for continuous

exposure and classrooms and conference rooms 15 cfm (about 7.1 L/s) per individual defined by

ASHRAE (ASHRAE, 2016)

Table 2.3 The effects of carbon dioxide on the human body (Engineering toolbox, 2020)

Normal outdoor level 350 - 450 ppm

Acceptable levels < 600 ppm

Complaints of stiffness and odors 600 - 1000 ppm

ASHRAE standards 1000 ppm

General drowsiness 1000 - 2500 ppm

Related health problems 2500 - 5000 ppm

Permissible exposure limit for daily workplace

exposures

5000 - 10000 ppm

The air in new constructions may contain harmful chemicals from the paints, glues, furniture, etc. and

the old buildings should be careful as well on the fungi, molds, spores, and dust hiding and spreading in

the building. It is necessary to assess the IAQ of the building from time to time.

2.3 Energy consumption in buildings

There are different types of energy sources in the building energy consumption which can be divided

into renewable energy such as solar energy, wind, waste heat, and non-renewable energy such as gas,

14

coal. Over half of the energy in Sweden generated by renewable energy sources. Hydropower and

bioenergy are the top renewable sources in Sweden which the hydropower is mostly for electricity

production and bioenergy is for heating (Sweden, 2020).

In Sweden, most of the buildings are required to meet a building code in terms of its energy performance,

which are the HVAC system, hot water, and building’s property electricity. Measurements and

monitoring system for energy use in buildings is mandatory so that how much actual energy

consumption can be read, calculated and checked if the building meets the requirements and the

buildings can maintain high energy efficiency. Sweden’s building code’s energy requirements are

extremely rigorous for both new builds and building renovations (GBPN, 2020). According to the

Swedish building regulation, the energy performance of the building (spacing heating, air conditioning,

hot tap water, and property energy) is expressed as a primary energy number which the total energy

consumption is aggregated and divided by the heated area of the building (non-heating area such as

interior walls, openings for stairs, etc. is excluded) and is in the unit of kWh/m2 per year. For premises

with a heated area of over 50 m2, the requirement of primary energy number is lower than 80 kWh/m2

per year (Boverket, 2018).

When Miljöbyggnad assessing the building, both the amount of energy use and type and energy are

included in the rating aspects (Swegon Air Academy, 2013). The expert group of Miljöbyggnad divided

the energy resources into three categories, renewable flowing energy, renewable fund energy, and non-

renewable energy according to how much resource withdrawal from nature they cause (Johansson,

Bagge, & Wahlström, 2018). Energy performances in one year for heating, domestic hot water, comfort

cooling, and non-domestic power use (excluding the business appliances) are calculated and 35% lower

than the building regulations can be certified Miljöbyggnad gold.

In a comparative study of energy uses in 20 office buildings in Poland, the average total energy

consumption of green-building certified buildings was 142 kWh/m2 and 144 kWh/m2 for uncertified

buildings but the heating consumption in certified buildings was 26% lower than the consumption in

uncertified buildings. The conclusion of the study is that designing a building applying the certification

requirements can save operational energy cost of more than 30% and has greater energy saving potential

during the operation phase due to the energy-efficient strategies in the designing phase (SKANSKA,

2020).

The energy for artificial lighting, IT equipment, and the HVAC system have steadily risen in office

buildings and count for 85% of the total energy use (Pérez-Lombard et al., 2008). In order to save the

energy costs during the operation stage, some energy saving strategies are proposed. For example,

designing a smart lighting system and a layout with efficient daylight, understanding the occupants’

energy use pattern, and applying automatic shading. A study on the energy consumption of office

buildings in London using a simulation model found that the night cooling using natural ventilation

lower the cooling demand both in rural areas and city and therefore is beneficial to the environment

(Kolokotroni, Ren, Davies, & Mavrogianni, 2012). Studying building behaviors can help to find

efficient energy saving methods to further improve the building and its sustainability.

15

3 The study case

3.1 U-house

Undervisningshuset (the U-house) is a multi-functional educational building of KTH on Brinellvägen

in Stockholm, Sweden. The climate of Stockholm is the oceanic climate with an average of over 1800

hours of sunshine per year. The winter seasons are long and cold but still remains above 0 ℃ for most

of the time and the summer times are mild (Klima-der-erde, 2020). The length of the day time varies

throughout the year, from more than 18 hours daytime in midsummer to merely around 6 hours in

December. The average winter temperatures are generally from −3 to −1 °C while the average

temperatures in summer range from 20–25 °C and up to 30 °C in midsummer from June to August. The

temperatures between winter and summer seasons are cool and mild (Wikipedia, 2020).

The building is designed for teaching and learning and is covered approximately 3500 m2 with 7 floors.

The appearance of the building is a brown beaver tail brick envelop which is energy-efficient whilst

kept with the almost 100-year-old tradition of KTH, with a slope roof, serving a unique artistic sensation

(Archdaily, 2018). There are various rooms for different study purpose and even the building could be

a tool for studying.

The design of Undervisningshuset has 7 floors with various spaces including lecture rooms, group study

rooms and open areas for a range of study uses. The spiral layout of the building, showing the space of

the building, is very clear to see the construction and installation (Archdaily, 2018). The building has a

high transparency with large glass walls, central stairs and a unique slope design. Meanwhile, there are

some dark and invisible function rooms and a weather station installed on the roof. The building

achieved features of both open and private, quiet, and transparent, serving diverse study demands.

The building is designed with a high focus on low energy use and is certified with Miljöbyggnad Guld

(Swedish Green building Gold) certified (Akademiska Hus, 2020) This certification has 16 index that

measures the performance and sustainability of a building. Karitikou evaluated the building in the

aspects of thermal, acoustic and visual perception of users in the building and checked that the building

meets the requirement of Miljöbyggnad Gold and it is in function properly (Kritikou, 2018). The

building also has an energy declaration that reported by Boverket on how much energy the building use

and for the U-house, the information is shown in Figure 3.1. The energy performance includes the energy

consumed by heating, air-conditioning, hot tap water and building’s property, and divided by the heated

surface of the building (Boverket, 2020).

Figure 3.1 Energy declaration of the U-house (Boverket, 2020)

16

3.2 Platform: Styrportalen

Collaborated with KTH live-in-lab, the building is a testbed for innovation in the building environment

and energy use. The building applied technology for studying how the building works including 767

sensors installed in the whole building and real-time monitoring system, and all the measurements can

be achieved by accessing the online application, Styrportalen (KTH//).

With the web-based application, today the plant information stored in the building management system

can be assessed from anywhere around the world. By using this application, it is possible to control the

building automation system without major investments.

Powered by Nordomatic, Styrportalen as a web-based system, enables the building management system

visible on any device. HTML5 gives you full choices of browser and hardware that the web-based portal

where all features of the building are accessible from web interfaces on Mac OS, Windows, iOS,

Android and WIN-mobile. Moreover, it’s open to all users around the world and is never limited to a

technology standard. It can fast access to the data with no place and time limit.

The measurement collection system is designed to be used by students, researchers with several to study

the properties of the building over time. It is uncommon that we get access to the signal system of a

building and it is rare that sensors are applied to the inner fabric of the building envelope, where is the

inner structure of the walls and roof. By adopting the system, an understanding of the buildings

behaviors and about how control systems might be improved can be obtained. The sensors include

temperature, humidity, CO2 level, power meters, etc. which enable users to analyze in different fields

of the building such as thermal comfort, IAQ. Therefore, the system for measurement collection should

meet high demands on reliability, stability and accuracy of the measurements. It is important to check

the function of the sensors and system from time to time.

Historical collection of data can be logged and used in trending applications to further improve plant

processes. as well as create mandated record-keeping for some of the industries out there. Moreover, the

system provides logically constructed address, and hence through Styrportalen the BMS of the building

can be programmed and combined with other software to further develop its usage.

17

4 Method

This part introduces the approach of using Styrportalen, accessing to the data of the U-house to explore

how this system can help to study the building. One of the features of the system is that trend analysis

is possible for different sensors and historical data. It is possible to either using the statistics to have a

quantitative analysis or look into the trend to have a qualitative analysis. Both of these methods can

contribute to studies about the building.

The study has features of a qualitative that collect the evidence and find the characteristics from the

trend. The system has three-year historical data to analyze and the quantitative calculation suits the study

of a shorter period. Besides, the thermal comfort index calculation for some extreme situations and

energy consumption comparisons are included in the study.

4.1 Styrportalen

To gain data, first of all, an account and the permission from Styrportalen should be set to access the

building information. In this case, entering the building with the building’s code KTH A0043032, the

overview, which is the shape of the building, and the placement of the rooms are demonstrated with a

function toolbox on the side, shown in Figure 4.1. By clicking different room button, the data from the

sensors are shown with a simple system drawing as an explanation, shown in Figure 4.2.

Figure 4.1 Overview of the building in Styrportalen

18

Figure 4.2 RU435 room illustration in Styrportalen

Using the toolbox on the side, the system could work as an alarm, an analysis tool, and storing different

documents and notes about the building. In “Anläggningar”, it is shown that the building can be explored

by different categories, such as the heating system, cooling and water circulation. The whole floor plan

with conditions of the room is visible from the sensors mounted in the room. The details of the sensors’

placements are shown along with the plan drawing as well. For example, in Figure 4.3, the 2nd floor plan

with different rooms and the meters with real-time data are demonstrated in this interface.

Figure 4.3 The plan of Floor 2 in Styrportalen

In the plan view, sensors are shown in the drawings with real-time data and alarm. The alarm system

can report the unusual situation automatically with warnings with red highlights in the system. The

sensors and meters can be viewed in the form of lists as well. It’s convenient for the operators to check

and maintain the building.

19

The main tool used by the thesis is the “Analys” where different sensors and meters can be selected and

added and making trend analyses of different periods. Therefore it is not only a real-time monitoring

system but also a system that can check the historical data within the system.

The sensor data can be simply selected by clicking it and there are two choices to see the “data trend” of

the sensors. One is directly clicking “Visa”, which means seeing in trend analysis and the other is “Lägg

till” which means “add to”. By adding the sensor, a list of different sensors can be selected and shown

in one diagram in trend analysis by clicking “Lägg till och visa”. The list of sensors can be edited as well

by using “Redigera valda”. In that case, the analysis of the combination of sensor data within the system

is easy and fast. The diagram that the tool generates could be saved and marked. The selected group of

sensors information can be stored in the cloud service of the system as well for using it at another time

but the time interval of the diagram cannot be memorized and would be reset to the last 24 hours.

Moreover, the data can be downloaded in different picture forms and the statistics can be exported in

excel files to have further analysis. Overall, through Styrportalen the building measurements can be

acquired and analyzed and it’s the core of this study.

4.2 Indoor environment assessment

4.2.1 Data from the sensors in the building envelope and weather station

The building as a study tool, its uniqueness is that there are sensors mounted in different layers of the

building envelope, enabling people to look into the fabric of the wall to see the process of the temperature

changes. In addition, the building has its own weather station located on the roof and its data is accessible

on Styrportalen as well. Therefore the real-time climate information of the surrounding area could be

gained.

Figure 4.4 Weather station of the U-house Figure 4.5 Weather station data in Styrportalen

Applying the data from sensors of the weather station when the condition is extreme in one way or

another: a very warm day, an extremely cold winter day. To be specific, selecting sensor “Temperatur”

in AM101 weather station, checking in a large period, and locating the extreme point. Nevertheless, the

precipitation information in the Stockholm region is acquired from the weather website SLB analysis

because it’s not available in the weather station.

The sensors are mounted in the façades on the 4th and 5th floor, and the roof, which completely show all

directions of the building. Through the trend analysis tool, diagrams are generated with temperatures in

different layers of the wall and different sides of the façade can be compared to see how the directions

20

affected the wall and room temperature.

In classroom U41 (room code RU420 in Styrportalen), sensor GT 47 is installed to measure the operative

temperature of the room as Figure 4.7 shown, which can be a useful reference for evaluating the thermal

comfort level of the room. There is no other room with this kind of sensor installed. Therefore, U41 is

selected to assess the thermal comfort of the lecture room.

A manual control system is installed in the lecture room and occupants can adjust the temperature

themselves to achieve a customized comfort level. This attempt is also visible in the system and through

this signal how occupants actually feel about the indoor environment can be inferred.

4.2.2 CBE Thermal Comfort Tool

For the thermal comfort prediction of the lecture room, the study applied the CBE Thermal Comfort

Tool (v2.0.0) developed by UC Berkeley. By applying the PMD method in the comfort tool, six thermal

comfort influencing factors can be input and according to the combination of the inputs, the PMD/PPD

is calculated complying with ASHRAE Standard 55 and displayed a visualization of comfort boundaries

within psychrometric or temperature-humidity charts, indicating the ranges of acceptable temperature

and relative humidity with the given inputs (Hoyt, Schiavon, Piccioli, Moon, & Steinfeld, 2019).

According to ASHRAE 55, the metabolic level input in the tool is 1.1 met during lectures and 1.3 met

before the lectures due to the fact that during the lecture people are seated and typing, reading and before

the lecture people tend to stand relaxed and chatting. The clothing insulation value is 0.8 clo in winter

between wearing long-sleeves, sweaters, jackets and trousers. In warmer days, the study applied a 0.5

clo value with typical summer clothes (ANSI/ASHRAE Standard 55-2010, 2013).

There are no air velocity sensors in the system and therefore using an average value of 0.08 m/s in the

warmer season and 0.09m/s in cold season according to the field measurement results from the previous

studies on the U-house by Kritikou (Kritikou, 2018).

Figure 4.7 Operative temperature sensor in

U41 (Akademiska Hus, 2015) Figure 4.6 Sensors in the structure of the

wall

21

4.2.3 Ventilation systems

The ventilation system in the room plays an extremely essential role in the building system since it has

functions of maintaining the thermal comfort of the room while removing or diluting harmful pollutants

in the air. As it is a subsystem of the building management system, the control and the output effects of

the ventilation system should be a key point to study.

Lecture rooms are installed with carbon dioxide sensors and airflow controls and hence the correlation

between the airflows and carbon dioxide level can be analyzed. Occupants in the indoor environment

are generally assumed to follow deterministic schedules in building performance simulation study

(Tekler, Low, Gunay, Andersen, & Blessing, 2020). Classrooms in the U-house are only for the lectures

and seminars and the schedules are available on the KTH website. It clearly shows when the room will

have or had lectures and events and it is reasonable to assume that there should be people present in the

room. However, the group room and open study place are not available on the schedule. For the open

study area, neither the schedules nor the sensors of carbon dioxide level are available since the open

area is difficult to define and measure the properties. Therefore this study focus on the indoor

environment in the room where it is predictable from the schedule and is data-available. U41 and U51

are two rooms chosen to explore the ventilation system. These two classrooms are on the opposite

directions of the building, the south side and the north side, and hence they can represent most of the

classrooms in this building.

4.3 Energy Analysis

The system includes meters to record the energy consumption of the building. The building is designed

to be low energy cost and real-time monitoring makes it possible to check the energy costs in different

periods, no matter warm days or cold seasons.

The total energy consumption of the building consists of heating, cooling, property use electricity and

tenant use electricity, which are measured by different meters visible in Styrportalen. The property total

energy includes the energy used by warming cable, air handling units, elevator and the building

structures. The tenant energy is for lighting, microwave oven, and other energy used by tenants such as

the office appliance which are measured separately on floor 1, 2, 4, 6, 7 in the technology room.

Figure 4.6 The Secondary heating system illustration in Styrportalen

22

There are independent energy meters in the heating system, district cooling and water system. For

cooling energy, it only has one meter KP101-MF401 to measure total cooling power. The real-time

power of total heating energy is measured by the meter VP101-MF401 and so are its subsystems in

terms of radiators (VS101-MF41), air door (VS101-MF42), ventilation (VS101-MF43, VS101-MF44),

hot tap water (VV101-MF401) and water circulation (VC101-MF41). By clicking the dialog of the

meters, the total energy use from the beginning of the operation till now can be checked. The thesis

focus on investigating the energy used in different seasons as well as a whole year consumption in

different categories.

4.4 Interview, documents from Akademiska Hus

The information and explanation of the system are all from exclusive documents and construction

drawings of the building which are owned by Akademiska Hus. The documents range from the control

system, automation system, structure drawings and the energy consumption report. These documents

are in Swedish and to fully understand it, google translate is used. The result and conclusion of the thesis

are drawn not only through the data from Styrportalen but also with the help of the explanation and field

inspection by Sven Lindahl, the engineer from Akademiska Hus.

23

5 Result

The building reacts to the factors such as the outdoor temperature, the occupants in many aspects and at

the same time, controlled by the control system of the building. The building behavior is the output of

the interaction with the climate, occupants and the control system. U-house has a complicated automatic

control system that maintaining the a safe and proper indoor environment under disturbance with

accurate instructions (Widström, 2018). Therefore understanding the components of the control system

such as the setpoints and the control signals help explain the response of the building and these subjects

and values are visible in Styrportalen.

Using the system sensors and meters, the building behaviors and the total energy consumption of the

building can be obtained and evaluated. The result is presented in such outline shown in Figure 5.1.

Figure 5.1 Outline of the result

5.1 The control system

In this part, the information about the control system is described.

For the classrooms in the building, the temperature setpoint is 22 ℃. There are two control mode,

comfort operation within and economy operation . Under the comfort modes, operation for a good indoor

comforts, the temperature are controlled within ±0.5 ℃. On the other hand, under economy mode, it’s

within ± 2 ℃. The classrooms only run in the comfort mode in daytime from Monday to Friday, 7:00 –

22:00 and this can be defined as the operation time of the building. At night and during weekends, it

runs in the economy mode.

Figure 5.2 shows how the sensors display in a lecture room in Styrportalen. During operation time,

temperature control via GT101 is switched on for comfort mode when the presence sensor GN501

perceives presence for 1 minute and returns to economy operation when there is no presence for 5

minutes. The supply air flow operates in the same way. The minimum flow occurs when there is no

presence or the sensors haven’t noticed the presence for 5 minutes, but when the sensor detected

24

presence for 1 minute, the ventilation runs according to the “presence flow”, which is a default value in

the control system. The values of the airflows are shown in ST401-GF and ST402-GF.

Users of the room can customize the temperature if they feel uncomfortable with the current room

temperature. Through sensor OS101 “Börvärde offset” which means setpoint offset, the users can adjust

the room temperature to reach their demand.

The carbon dioxide sensor GQ101 has an automatic control system linked to the airflow sensors with

the actual setpoint of 800 ppm instead of 900 ppm which is recorded in the document.

Figure 5.2 Sensors in RU420

The building operates a default night cooling of 15 ℃ in hot days as the Swedish building regulation

recommend to reduce the demand for cooling load in warmer days (Boverket, 2018). That explains why

there is some time that the temperature setpoint offset OS101 shows 15 ℃ instead of 22 ℃ in

Styrportalen.

Classroom U41 has a sensor for measuring operative temperature and therefore the thermal comfort in

this room is studied.

5.2 Building behavior

5.2.1 Interesting moments

The occupants in the building is a control point for facilities to operate (Kayo, 2018) and the main users

of the U-house are the students who have lectures or work on their own in the building. Therefore, the

indoor environment when there are users in the building should be focused and that is during the

academic period of KTH. In this part, the analysis chose the most recent study period, from 2019 to

2020. This includes the spring term of academic year 2018 – 2019, from 15 January to 4 June, 2019 and

academic year 2019 – 2020, till 30 April, excluding weekends and holidays (KTH, 2020). These periods

consist of the summer of 2019 and cold time from 2019 – 2020.

25

Figure 5.3 Timetable of Academic Year 19-20 (KTH, 2020)

Through the weather station the temperature around the building for a whole year can be obtained.

Figure 5.4 Outdoor temperature around the U-house from April, 2019 to April, 2020

26

Figure 5.4 shows an overview of the temperature around the U-house in a whole year. The warm season

is from May to August and most of these time are holidays when nobody will appear in the building.

Excluding the holidays of school, clearly the hot season is from the mid of May to the early June and

the cold season are throughout December to the end of March.

A comparison can be done between data from the weather station at the U-house and the data from SLB

analysis (Stockholm Air and Noise Analysis) which is a department at the Swedish Environmental

Administration provided by the web link slb.nu shows that the data from the weather station are reliable

and so some interesting moment for inspection can be decided. The building are inspected in two

periods, the warmer period from Monday, 13 May to Tuesday, 4 June, 2019, and the cold days from

Monday 20 Jan to Monday 17 Feb, 2020. The following analysis are based on these period though some

extension were still made for analyzing.

Figure 5.5 Temperature at weather station

(Warmer period)

Figure 5.6 Temperature at weather station

(Cold period)

Figure 5.7 Temperature at warmer period

(SLB, 2020)

Figure 5.8 Temperature at cold period

(SLB, 2020)

27

5.2.2 Building behavior in Cold days

5.2.2.1 Building envelope: The Roof

A weather station and 7 sensor spots are installed on the roof, shown in Figure 5.10. Sensors GT41 to

GT44 are placed in between three 100 mm thick insulation boards “PIR TR20”, a high performance rigid

thermoset plastic insulation which are illustrated by a triangle patten in Figure 5.9. This material is

moisture resistant and suitable for a flat roof insulation (Kingspan, 2013). The rest of the sensors are

placed in the structure components (the trapezoid sheets, the sound absorbents and concrete) of the roof.

Using trend analysis to check how temperature changed in different parts of the roof. GT41 to GT46

and the outdoor temperature are added and south and north sides of the roof are compared.

Figure 5.12 Temperatures at Roof-RU560 (South) Figure 5.13 Temperatures at Roof-RU620 (North)

Figure 5.10 Sensors placement on the roof

Figure 5.9 Sensors in the roof structure for index 1-5

Figure 5.11 Sensors in the roof structure for index 6-7

28

Figure 5.14 Temperatures at Roof-RU750 (South) Figure 5.15 Temperatures at Roof-RU632 (North)

From the figures, the insulation prevent the heat loss layer by layer. The thermal conductivity of 100mm

PIR insulation is merely 0.026 W/mk (Kingspan, 2013) and it performed a good thermal insulation that

between GT41 (blue lines), GT42 (red lines), GT43 (yellow line) and GT44 (green line), there are three

large gaps. On the other hand, the temperature between the trapezoid sheet or the concrete are very close,

indicating the materials have a high heat conductivity. Exceptions happened in GT43 of RU560 while it

shows an unnormal high temperature. This will be discussed in Chapter 7 Discussion.

Through comparison, the sensors in the south part of the roof displayed distinctly higher outdoor surface

temperatures on 2, 3, 13, 14 Feb than what were registered on the north side. This abnormal high

temperature was caused by the direct sun radiation given the fact that it happened only on sunny day at

around 2 pm (Timeanddate, 2020).

Figure 5.16 Stockholm weather from 10 Fen to 15 Feb

Therefore, it can be concluded that, though it’s in cold season, the roof of the building can have an

uneven surface temperature due to the solar radiation.

It is relevant to inspect data from the two rooms under the places where the sensors RU632 and RU742

are placed.

29

Figure 5.17 Temperatures comparison between RU632 and RU742

Figure 5.17 shows that the two rooms have similar temperature at ceiling surface (GT46) and room air

temperatures (GT101) despite that the rooms are located on the opposite side of the building with

different outdoor surface temperature (GT41). As a result, the three layers of the roof insulation is

sufficient for prevent the heat loss in cold season.

30

5.2.2.2 Building envelope: The wall

The building has sensors installed in the wall of floor 4 and floor 5 with two sensors in the north, two in

the south and each one for west and east, shown in Figure 5.18 and Figure 5.19. It allows to compare

the insulation performance in the wall from all the directions.

Figure 5.18 Floor 4 plan with detail illustrations

Figure 5.19 Floor 5 plan with detail illustrations

As the detail illustrations show, there are always five temperature sensors in the same positions of the

wall. The structure of the walls are identical to each other but different from the roof. Take spot “RU420-

NORR” as example, GT41 is placed in the airgap with battens. Between GT41 and GT42 is a 100 mm

insulation with steel girders. Then, followed with an 195 mm thick insulation with steel girders where

31

lies GT43. The thin layter between GT43 and GT44 are two layers of plaster. Lastly, there is one more

layer of 95 mm insulation with steel girders and GT44 and GT45 are mounted inside this layer. No

details about the material of the insulation from the drawings (Akademiska Hus, 2015).

Figure 5.20 Temperatures at Wall-RU560-South Figure 5.21 Temperatures at Wall-RU 420-North

Figure 5.22 Temperatures at Wall-RU550-South Figure 5.23 Temperatures at Wall-RU560-West

From the diagrams, the gap between GT42 and GT43 are obvious due to the insulation materials and it

keep the heat from leaking. That means the 195mm insulation performed well and its thermal

conductivity is low. Assuming the material of the insulation is the same as the insulation in other layers

of the wall and in that case it can be concluded that thicker the insulation, the lower the thermal

conductivity. In the façade of RU560, the break-out open space, the effect of the 95 mm insulation can

be seen clearly through the diagram while in the classroom RU460 and RU550, the 95 mm insulation

does not work that well.

The outdoor surface temperature is nearly similar in different facades except some spikes on the south-

west wall of RU560. It indicates a mild sun radiation on this direction, making the surface of south-west

part warmer. Even though, it hasn’t affected the temperature in the next layer.

It can be noticed that in RU420 and RU550, room surface temperature has small fluctuations along with

the movement of the outdoor surface temperature. Therefore, the trend of the outer surface temperature

still have impact on the indoor environment.

5.2.2.3 Rooms: U41 (RU420) & U51 (RU550)

RU420 and RU550 are two classrooms with multiple sensors in Styrportalen with room number U41

and U51 respectively in the KTH course system. Through sensor data, the indoor climate of two rooms

was evaluated.

32

Thermal Comfort

Temperature sensor GT47 in RU420 is used for measuring the operative temperature. Through this the

thermal comfort index, PPM and PPD value can be calculated. The analysis should exclude the non-

operating time. Therefore, only the data Monday to Friday from 7:00 – 21:00 is selected and shown in

Figure 5.24.

Figure 5.24 Operative temperature and relative humidity of U41

The extreme moments are selected as well as an average value of the room operative temperature and

relative humidity is calculated.

Table 5.1 Extreme and average values of operative temperature and RH in U41

maximum minimum average

Operative temperature 26.5℃ (28/1 19:00) 21.7℃ (3/2 7:17) 23.8℃

RH 45% (28/1 17:43) 28% (3/2 7:27) 36%

From the schedule of U41, there was no arrangement when the max and min operative temperature

occurred but there was a lecture at 17:00-19:00 (KTH, 2020) on 28 Jan with over 25 ℃ operative

temperature while at the same time the humidity was 45%. The lowest relative humidity occurred almost

at the same time when the temperature dropped to the lowest point. Therefore, two extreme cases were

selected to calculate the thermal comfort at that time, 18:00 on 18 Jan and &:30 on 3 Feb. The calculation

is by the CBE thermal comfort tool and several inputs were required.

Inside the building the air speed could be slow but there is no sensor in the system that measuring the

air velocity. Nevertheless, in previous research regarding to the U-house, Kritikou measured the air

speed in the building in both heating-operation session and cooling session. Therefore, the study took

33

value of the air velocity of 0.08 m/s in the heating session and 0.09m/s in the cooling session (Kritikou,

2018).

Occupants of one room with significantly different activities shall not be averaged to find a single

average metabolic rate. As the students in the lecture room are assumed to do uniform activities, having

the lecture together, doing things like typing, being seated and talking, therefore the metabolic level is

assumed to be 1.1 met. Before the first lecture of the day, however, the situation at this time is the

occupants come into the building for lectures in advance and they tend to stand, wait and chatting instead

of having lectures. Therefore the input metabolic level before the lecture is assumed to be 1.3 (between

standing relaxed 1.2 and filing, standing 1.4) according to the ASHRAE Standard (ANSI/ASHRAE

Standard 55-2010, 2013).

Table 5.2 Metabolic Rates for typical light task (ANSI/ASHRAE Standard 55-2010, 2013)

On the other hand, in winter, for the clothing insulation in heating-dominated season, people tend to

wear long-sleeve shirts, sweaters and trousers in indoor environment and therefore a 0.8 clo insulation

level is assumed (ANSI/ASHRAE Standard 55-2010, 2013).

Overall inputting the required values to the CBE thermal comfort model and the results are automatically

shown.

34

Figure 5.25 Case 3 result in CBE Thermal Comfort Tool (Hoyt, Schiavon, Piccioli, Moon, & Steinfeld,

2019)

Table 5.3 Summary of the three scenarios input and results

Case 1: at 18:00, 28/1 Case 2: at 7:30, 3/2 Case 3: average value

input temp 25.5 22 23.8

input humidity 45 28 36

air speed 0.08 0.08 0.08

metabolic 1.1 1.3 1.1

clothing 0.8 0.8 0.8

PMV 0.40 -0.10 0.00

PPD 8% 5% 5%

Sensation Neutral Neutral Neutral

From the summary, the thermal comfort level of different scenarios can be known. U41 performed an

average excellent thermal comfort. However the input is based on various assumptions in air speed,

clothing insulation and metabolic level and the precise PMV and PPD value at that time should be further

verified using more detailed measurements.

Through setpoint offset sensor OS101 in the room, it can be known that though the room is located in

the north side, the setpoints kept the default setpoint 22℃, indicating an overall satisfied thermal comfort

in U41.

35

Room indoor air quality

Sensors that monitoring the carbon dioxide level and airflows are analyzed to check the indoor air quality

of U41 and U51.

Figure 5.26 Overview of airflows and carbon dioxide level in U41

As Figure 5.26 showed, U41 in winter has an overall adequate ventilation that the CO2 concentration

was controlled under 1000 ppm. The ventilation rate rise along with the carbon dioxide level.

Through the timetable of the classroom, the occupants presence of the room can be confirmed. It is

assumed that when there was lectures, the room is full.

Figure 5.27 One-week timetable in cold days of U41

36

From Figure 5.27, through Monday to Friday this week, there are lectures arranged in U41 including

evening lecture on Tuesday and Thursday.

Figure 5.28 One-week airflows and carbon dioxide level in U41

From Figure 5.28, the carbon dioxide level in U41 is sensitive to the people’s presence. It rise as soon

as the students come in and the lecture started. The ventilation increase the air flow when there is

presence of users. The highest CO2 rate is over 800ppm which is acceptable for the study performance.

The ventilation system starts when the building start operating at 7 am with a sometimes large supply

and exhaust amount for a very short time. It shut down at 21:00 and on Sunday the ventilation doesn’t

operate as well. When the room is empty during the operation time, the airflow remains a basic level

with around 100 L/s – 110 L/s in supply and around 130 – 150 L/s in exhaust to ventilate. At that time,

the CO2 level is around 360 ppm which is equal to an outdoor level.

The ventilation system is also related to the room air temperature. In Figure 5.29, it demonstrates the

outdoor surface temperature RU420-GT41, the outdoor air temperature AM101-GT91, the room surface

temperature RU420-GT45 and the room air temperature RU420-GT101.

37

Figure 5.29 Temperatures related to U41

From Figure 5.19, the room air temperature has no evidence that it has correlation with the outdoor air

temperature or the surface temperature. It has a feature of being time-related. For analyzing the room

air temperature and the ventilation rate, Figure 5.30 has been achieved.

Figure 5.30 Supply airflow and room air temperature

Figure 5.30 shows that the room air temperature is adjusted by the ventilation rate and when it stops

ventilate the room the temperature rise above the setpoint. The ventilation system helps to maintain a

constant and comfortable temperature in the room.

38

Another classroom U51 on the south side of the building is studied.

Figure 5.31 Overview of airflows and carbon dioxide level in U51

In U51 the CO2 concentration is up to 900ppm but it still satisfied the requirements of under 1000ppm

CO2 level. Overall, the ventilation operates well.

Applying a relatively loose schedule of U51 but still during the cold time, from 17 Feb to 23 Feb to

check the indoor air quality.

Figure 5.32 One-week timetable in cold days of U51

39

Figure 5.33 One-week airflows and carbon dioxide level in U51

Obviously the presence of people in the room is the reason that the CO2 level rise. The ventilation rate

rise when it starts operate or when there is presence of people. Even on Sunday, the ventilation

automatically operated for a while.

When the building is still operating and the room is empty, the minimum supply airflow is around 50L/s

and the extract airflow is slightly larger than the supply while in U41 the empty room ventilation rate is

larger though they have almost the same area.

Figure 5.34 Temperature – Carbon dioxide level combined illustration

From Figure 5.34, the temperature maintained around 21 ℃ to 22 ℃ when the ventilation operates.

Besides that, in U51, a slightly rise of temperature can be noticed.as soon as the occupants came in

and the CO2 level reach to the peak. Before the occupants came in, the room is a little colder than the

40

setpoints of 22 ℃. The outdoor surface temperature is not the reason cause the rise because there is a

little peak in the surface on 22 Feb but there is nobody in the room and no rise in the room temperature.

Therefore, it’s the room air temperature has a correlation with the occupants. This evidence can also be

found in U41 but it is not as obvious as in U51.

5.2.2.4 Heating energy

Figure 5.35 Heating power – Outdoor air temperature combined illustration

The outside temperature and the heating power are shown in Figure 5.35 as comparison. It can be

concluded that the outside temperature affects the heating power of the building and the lower the

outdoor temperature the bigger the power supplied by the radiators.

41

5.2.3 Building behavior in warmer days

5.2.3.1 Building envelope

In the warmer days, direct strong sun radiation will definitely cause an extreme high temperature on the

roof. It is important to keep the heat out of the building to reduce the cooling load. The outside air

temperature AM101-GT91 is added to compare.

Figure 5.36 Temperatures at Roof-RU750 (South) Figure 5.37 Temperatures at Roof-RU620 (North)

From the figure, the sun radiation on the roof is strong in warmer days all over the roof. The outdoor

surface temperature is the highest among all the sensors and the peak occurred always around 2-3pm.

In addition, there was low outdoor surface temperature on several days that no obvious spike peak on

these days afternoon. It may have correlation with the weather on that day.

Figure 5.38 Precipitation profile of the Stockholm region (SLB, 2020)

Figure 5.38 shows the precipitation of the Stockholm region in May. Given that fact that it was rainy in

the afternoon on some days with no peak at the façade surface, 19, 23, 26 27 of May. Therefore, the

reasons why there is some time that the roof temperature were lower than the other hot day is that the

rain took most of the heat from the surface. The indoor environment haven’t been affected by the

radiation or the rain.

For further comparison the highest façade temperature from May 13 to May 22, are shown in Table 5.4

42

Table 5.4 The everyday peak outdoor surface temperature

13/5 14/5 15/5 16/5 17/5 18/5 19/5 20/5 21/5 22/5

RU750

South (℃)

36.6 60.6 58.0 61.9 59.5 55.8 25.7 60.0 63.3 68.8

RU620

North (℃)

31.8 43.1 46.0 48.2 45.4 46.0 26.8 51.4 52.1 56.6

From the table, it is obvious that temperature on the roof surface is uneven and the south side has a

stronger radiation than the north side. There is a larger temperature difference in different side of the

roof during warmer days.

Figure 5.39 shows the detailed changes in the roof. The heat is slowly conducted to the next layer and

reduced. Eventually, the room surfaces have uniform temperatures. This process in the roof repeated

every sunny day.

Figure 5.39 One-day Temperatures in Roof-RU620

As a result, the insulation process in the wall is identical to that in the roof. Outside heat is reduced and

insulated by every layer of insulation in the same pattern. The north part of the walls have a lower solar

radiation than the south side, see Figure 5.40 and Figure 5.41.

Figure 5.40 Temperatures in Wall-RU560-South Figure 5.41 Temperatures in Wall-RU420-North

43

5.2.3.2 Rooms: U41 & U51

Thermal Comfort

To find the extreme uncomfortable moments, the data of operative temperature and relative humidity of

U41 from 23 May to 4 June are selected. Nevertheless, from 21 May to 24 May is the period when

students are doing work on their own, so there were no lectures on these days. In addition, 30 May is

national holiday so the room is assumed to be empty as well. As a result, the data of these period were

deducted as well. The operative temperature and relative humidity changes during operation time are

shown in Figure 5.42.

Figure 5.42 Operative temperatures and relative humidity of U41

Table 5.5 Extreme and average values of operative temperature and RH in U41

max min average

operative temperature 28.8℃ (31/5 17:12) 21.8℃ (15/5 7:18) 26.0℃

RH 50% (20/5 20:56) 23% (14/514:03) 33.8%

There were two times in this period that the operative temperature has reached over 28 ℃, 17 May and

31 May. Both of two high temperature case and other extreme values were calculated as different

scenarios in the CBE Thermal Comfort Tool.

For the warmer clothing values, it is assumed that during the lecture the occupants wear a typical summer

clothes with 0.5 clo but in the early morning before the first lecture of the day, people have light outwear

with 0.8 clo. The metabolic level is 1.1 met during lecture time and 1.3 met before the very first lecture

of the day. The air speed is 0.09m/s (Kritikou, 2018)

44

Figure 5.43 Result of average case in CBE Thermal Comfort Tool (Hoyt, Schiavon, Piccioli, Moon, &

Steinfeld, 2019)

Table 5.6 Summary of the scenarios inputs and results

Scenarios 14/5 14:03 15/5 7:18 17/5 14:12 20/5 15:47 31/5 17:12 Average

input temp. (℃) 25.5 22 28 26.5 28.8 26

input RH (%) 23 30 39 48 31 33.8

air speed (m/s) 0.09 0.09 0.09 0.09 0.09 0.09

metabolic (met) 1.1 1.3 1.1 1.1 1.1 1.1

clothing (clo) 0.5 0.8 0.5 0.5 0.5 0.5

PMV -0.14 -0.13 0.79 0.38 0.98 0.10

PPD 5% 5% 18% 8% 25% 5%

Sensation Neutral Neutral Slightly

Warm

Neutral Slightly

Warm

Neutral

45

From the calculated result Table 5.6, there were two times that the room has a bad thermal comfort. On

the afternoon of 17/5 and 31/5, the thermal environment is too warm for the students in the lectures or

in an exam. The timetable for this period is not available anymore on the KTH website but the bad case

happened during the operation time. Though there can be any deviation on the clothing insulation, air

speed and metabolic level, over 28 ℃ operative temperature is still too high for a comfortable

environment. The overall performance on thermal comfort of this room is good with 5% PPD during

this period.

Through OS101, how occupants in the room manually adjusted the setpoints to lower the temperature

can be viewed to check how people actually felt towards the indoor thermal environment.

Figure 5.44 Temperature setpoints of U41

During this period there were four occasions when the users did adjustments to lower temperature

setpoints of U41 and three of the times have been selected as the extreme period in the thermal comfort

calculation. On 17 May and 31 May when the calculation indicates the indoor environment was warmer

than desirable, the users lower the temperature during this period. That means, the occupants did have a

hot sensation and the cooling was insufficient at that time.

From the data, a fairly high operative temperature of 27 ℃ occurred at 11:03, 14 May. On the same day

afternoon, with a lower temperature setpoint adjustment from 10:06 to 18:44, the calculation indicates

the room ran a fair cooling load of 5% PPD.

Indoor air quality

The timetable of the last academic year is not available on KTH website and the period from August 26

to September 1 was replaced and studied as during this time the weather was hot as well.

46

Figure 5.45 One-week Timetable in warmer days of U51

Figure 5.46 One-week airflows and carbon dioxide level in U51 in warmer days

Compared to the ventilation in cold days, the average operation airflow is obviously much larger than

the flow in cold days. When the room is empty during operation time the airflow is over 200L/s. When

there was presence in the room or the night cooling started operating, the airflow reached its max flow,

which is 800 L/s in U51 (Akademiska Hus, 2015). At this point, the CO2 concentration was lower than

800ppm, indicating that the ventilation in U51 was adequate.

Nevertheless, in U41, the measurements results implies a lack of ventilation. Surprisingly, in 2019 from

January to August, the ventilation of U41 only operates at a minimum level of around 55 L/s even when

the room has an extreme high CO2 level, over 1600ppm, a poor indoor air quality and it would affect

47

the performance of the students in the classroom. The insufficient ventilation rate can also explain the

unsatisfied thermal comfort in U41. Further inspection should be done regarding to the room during this

period.

Figure 5.47 Airflows and carbon dioxide level in 2019

5.2.3.3 Cooling energy

The cooling energy during hot season could be known from sensor KP101_120_MO401.

Figure 5.48 Cooling power - outdoor air temperature combined illustration

It is shown that on normal days the cooling is operating at a low level but on 20, 21 22 May and 4 June

the building required a large amount of cooling energy and it was associated with the outdoor air

temperature. When it was over 20 ℃ outdoor the building required over 45 kw cooling energy to operate.

48

Though when the outdoor temperature is no larger than 20 ℃, a very low amount of energy is still

required. The building keep consuming a little cooling energy even when the weather was cool due to

the night cooling and the ventilation.

Compare energy used in 28 days during 8 May to 4 June and during 1 Feb to 28 Feb, when there were

both 20 workdays and 8-day weekends with the nights and holidays excluded.. Adjust time from 8 May

to 4 June, the total amount of 1927.8 kw cooling power in one month can be achieved. Compared to the

cooling power of 504.5 kw in February, it is obvious that much larger cooling energy is need in the

warmer days.

5.3 Energy consumption

Through the meters in Styrportalen, the energy consumption in different categories and the total energy

consumption are shown in Figure 5.49.

Figure 5.49 Total energy consumption of the building in 2019

The tenant total energy use includes the lighting, microwave ovens, data processing of the building and

the rest power that consumed by the appliance of users. The property total counts for the energy used

by air-handling units, warming cables and the rest property used energy.

From the figure, the highest consumption happens in January and the lowest is in July. The property

total energy was constant due to the design and structures of the building. However, though the building

completely stopped operation due to the holidays in July and there was few occupants in the building

from June to August, it still consumed tenant energy. From the meters, during these months, the building

still consumed energy by lighting, projectors, printers. Therefore, these office equipment can be

switched off during holidays to save energy since nobody uses these equipment during summer holidays.

The differences in heating and cooling energy use between seasons is obvious. January costed the most

heating that occupied more than half of the total energy use of the building due to the extreme cold

weather in the winter of 2019. June and August consumed a large amount of cooling since there were

0

5000

10000

15000

20000

25000

30000

35000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

kW

h

Energy consumption in 2019

Cooling Total heating Tenant total Property total

49

some occupants in the building. Even in the warmer day, the building still consumed heating energy.

There were errors in several heating meters which were analyzed in the discussion.

In total, the yearly energy consumption was 262.55 mwah which divided by the building area of 3500

m2, resulting in the energy performance was 75 kWh/m2.

50

6 Discussion

6.1 Feedback and fault diagnosis

The building has 767 sensors which provides so much information that the building performance in

many aspects can be measured and assessed. As a result, information missing or in disorder, inaccurate

data and broken meters is inevitable in the system. During the research of the study, some abnormal

sensors and data are found and will be discussed in this part. This can be a feedback to the operator of

the system to fix and improve the building management system.

1. Sensors installed in the wrong place on the roof

Figure 6.1 Sensors placement illustration Figure 6.2 Sensors at 7TR1 and 7TR3 in the structure

7TR1 and 7TR3 are two spots in the roof fabric that places sensors in layers and the positions are shown

in Figure 6.1. They are very close to each other and are supposed to have similar measurement results.

Figure 6.3 Temperatures in 7TR1 Figure 6.4 Temperatures in 7TR3

When comparing the signal data from the sensors, it can be noticed that GT44 (the green line) and GT45

(the purple) in two spots have opposite results.

In 7TR1, GT45 has the highest temperature value while in 7TR3 GT44 has the highest value. Regarding

to other sensors on the roof, the most inside sensors GT45 usually have a higher value that close to the

indoor temperature in cold weather. Therefore sensors in 7TR3 could have errors. Further analyzing the

result, spots 7TR1 and 7TR3 are supposed to have similar trend of temperature changes in the same

layer and so are GT44 and GT45. It can be concluded that the position of sensors GT44 and GT45 have

been mixed up and GT44 in 7TR3 actually measures the temperature where GT45 should be and GT45

measures the temperature which should belong to GT44.

51

2. Missing data in carbon dioxide sensor in U41

There is no historical data recorded in the carbon dioxide sensor of U41 during two periods in 2018,

shown in Figure 6.5. The discontinuous data can be a problem for analyzing. For example there have

already been some field measurements regarding to the building in previous research and it could have

been a comparison with the historical data in the system.

As a result, there are errors and problems in the sensors and this also affects the validation of the

measurements in 2019 when U41 displayed a high carbon dioxide concentration. The cause and effects

of this error should be further studied.

Figure 6.5 Absent data of U41 carbon dioxide sensor in 2018

3. Broken meters in Plan 2 tenant lighting

On floor 1, 2, 4, 6, 7 there are electricity meters for measuring tenants energy use in terms of lighting,

microwave oven and other else. However, the lighting meter on floor 2 have been shown 0 kW and no

historical data can be found. As a result, the total energy consumption in lighting cannot be calculated

by using the data from sensors through Styrportalen. It can be concluded that the meters for tenant

lighting on floor 2 is broken.

The total fixed lighting is a part of energy consumption in the energy performance defined by the

Swedish building code (Boverket, 2020) and hence the data is important for calculating right energy

performance. Further repair should be done on this meter so that the complete information about the

energy use by occupants can be acquired and record for operation and study.

4. Impossible data in the energy meters.

While calculating the cooling or heating energy, some abnormal values appeared in the power meters

constantly in 2019 and wrong calculation may yield because of this. To be specific, on 19 Feb, 27 March,

13 April, 5 Oct, 5 Dec, there were cooling power recorded of -9992 kW for 1 minute which is impossible

to happen. In order to calculate a fairly accurate total cooling or heating energy, the power at that minute

was assumed to be the average value between the last minute and next minute.

5. Meters for heating energy

The total heating energy is consists of the radiator, the ventilation, the hot tap water, and the heating for

the entrance. Nevertheless, there are several errors in the heating energy sensors. After inspection by

Sven Lindahl, the meter for hot tap water VV101_MF401 has not been installed where the drawing

displays so that it cannot measure the energy consumed by the whole hot tap water system where the

52

heat loss is not taken into account. As a result, the hot water system energy can be calculated by adding

up the values of the hot tap water heating VV101_MF401, water circulation VC101_MF41, and heat

loss in the hot water system which is assumed to be 0.7 kW all the time according to Sven Lindahl.

Meter VS101_MF41 measures the energy use for the heating of two entrances of the building. However,

the meter was installed on the wrong side and there was always 0 kW shown in Styrportalen until 25

May when it was fixed. Consequently, there is no record for previous heating for the entrances. The

values for this part are obtained by the total heating energy deducting the rest of the three categories.

In that case, the heating energy for different parts of the building can be known, which is presented in

Figure 6.6.

Figure 6.6 Total heating energy use in 2019

In cold days the building uses a large amount of heating energy. The room radiators in the cold season

had a large consumption of energy and in warmer days there was no need for radiator or ventilation

heating.

The hot tap water in the building costs a small amount of energy due to the reason that there is no need

for shower or large domestic water requirements by occupants and the amount is constant over the

year. and not dependent neither on the outdoor temperature nor on the load of people in the building.

6. Sensors in the wall near the window

Among all the sensors in the wall, one place is very different than others. It happens in RU432-North

with very unstable temperature in the first insulation layer measured by GT42 shown in Figure 6.7. The

effect of insulation is not obvious in RU432-North. In other part of the wall, the trend of temperature

changes are similar.

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Total heating energy consumption in 2019

Hot water system Radiator Entrance heating Ventilation

53

Figure 6.7 Temperatures in Wall-RU432-North Figure 6.8 Temperature in Wall-RU432-East

Though RU420-North share the same wall and RU432-east share the same room and is even close to

the spot, the temperature in the wall differ largely. Therefore, the effect of occupants and climate can be

excluded.

To find out the reasons, the structure of the building is checked. It turns out that the sensor is mounted

at detail 8 shown in the figure. The installation place in only a few centimeters from the window while

all other sensors are more than half meters away from the windows. The opening affects the insulation

and the sensors shows how the temperature changes in such a unique spot.

Figure 6.9 Drawings of RU432 (Akademiska Hus, 2015)

This happened all by chance, but it is interesting to be able to study this effect. In the future it can be

related to wind loads for example.

6.2 Future research and reflection

Through inspection in different aspects of the building, problems and errors are detected and there are

unknown questions remained for future research.

The solar radiation has a huge impact on the temperature of the facades and the window orientation

should be further evaluated. The radiation will affect mean radiate temperature and the thermal comfort

for occupants close to the south side window. The automatic shading is a possible method which can be

designed according to the surface temperature of the outdoor façade temperature. The shading may

improve the insulation, the visual comfort and save the energy.

54

The thermal comfort calculation in the thesis is rough due to many assumptions and without a field

measurements and survey. Future work can be done through a questionnaire combined method to

explore the thermal comfort of the room.

More inspections on the room indoor air quality of U41 should be done because of the abnormal data

from the sensors. This sensor have other problems such as missing data in 2018 and therefore the data

in 2019 can be unreliable and it is important to confirm the indoor air quality in 2019 and avoid further

discomfort.

The carbon dioxide level has connections with the number of occupants as well. However the number

of occupants in any of the room cannot be obtained online and the quantitative study and the correlation

between number of occupants and the carbon dioxide concentration cannot be found through

Styrportalen. One proposal for a further study is to combine the data from the carbon dioxide sensors

with a counting of the number of occupants in a room to find this relationship.

The data that the building system provided are so extensive that there are plenty of opportunities for

future research studies that highlight an number of different aspects by using these data. Further study

can for example, be extend to include the humidity, or the air pressure sensors which haven’t been

focused in this thesis. For a more detailed and complete analysis of the building, a more detailed

quantitative analysis could be done as well, using the formula and equations and the statistics exported

from the sensors to evaluate the indoor climate of the building and study the building behavior. In

addition, the field measurements can be added as a comparison study as well as a check for the accuracy

of the sensor signals and the validation of the measurements.

Overall, the building management system is a tool for the students to explore the building technology

and performances and it is worth more studies and researches.

55

7 Conclusion

Through BMS of the U-house, the following findings can be concluded.

1. The system is easy to use and various aspects of the building indoor climate and energy can be

measured. It is a good tool for studying the building and it is recommended to use this system

to conducted relevant researches about the indoor environment of the building.

2. The building envelope performed well to maintain the indoor environment and avoid influence

from the outdoor climate. Solar radiation in the south side has impacts on the façade surfaces,

making the surface temperature uneven.

3. The overall thermal comfort is good but a few extreme conditions exist. Occupants can adjust

the room temperature by the control system installed in the classroom.

4. The ventilation system starts operating when there is people’s presence, regulating the

temperature and carbon dioxide level. When the carbon dioxide level exceeds 800 ppm, the

control system will automatically start to keep the level down to ensure the indoor air quality.

Overall the ventilation system is sufficient and maintains a good indoor air quality except for

U41 in the first six months of 2019. During that time, a high carbon dioxide level was recorded

and further examination should be performed to find out what happened during that time.

5. The building has an overall good energy performance with total energy consumption of 262.55

mWh and 75 kWh/m2 including the energy used by the office equipment and appliances. The

energy can be further saved by shutting down some of the office appliances and lighting during

holidays.

6. There are misconfigurations in the sensors mounted in the roof and it can be fixed by the owners

of the building. A constant check for the BMS is necessary for keeping a high-quality data

record both for maintenance and researches.

7. Further researches can be done in different aspects and comparative field measurements are

recommended to check the validation of the sensors’ measurements.

56

Reference

Abdou, A. A., & Budaiwi, I. M. (2005). Comparison of thermal conductivity

measurements of building insulation materials under various operating temperatures.

Journal of building physics, 29(2), 171-184.

Akademiska Hus. (2020). Undervisningshuset. [Online] Available:

https://www.akademiskahus.se/vara-kunskapsmiljoer/byggprojekt/vara-

byggprojekt/stockholm/undervisningshuset/ [Accessed on 17 Apr, 2020]

Akademiska Hus. (2015). Bilaga1 - Ritningar underlag Internal KTH

Undervisningshuset Report: unpublished.

Akademiska Hus. (2015). KTH_43_32_Mätningar_PLAN_1-8 Internal KTH

Undervisningshuset Report: unpublished.

Al-Homoud, M. S. (2005). Performance characteristics and practical applications of

common building thermal insulation materials. Building and Environment, 40(3), 353-

366.

Al Horr, Y., Arif, M., Kaushik, A., Mazroei, A., Katafygiotou, M., & Elsarrag, E. (2016).

Occupant productivity and office indoor environment quality: A review of the literature.

Building and Environment, 105, 369-389.

ANSI/ASHRAE Standard 55-2010, A. (2013). Thermal environmental conditions for

human occupancy. American Society of Heating, Refrigerating, and Air-Conditioning

Engineers, Inc.: Atlanta, GA.

Archdaily. (2018) KTH Educational Building / Christensen & Co. Architects [Online]

Available: https://www.archdaily.com/901046/kth-educational-building-christensen-

and-co-architects [Accessed on 17 Apr, 2020]

Asdrubali, F., Baldinelli, G., & Bianchi, F. (2012). A quantitative methodology to

evaluate thermal bridges in buildings. Applied Energy, 97, 365-373.

Asdrubali, F., D'Alessandro, F., & Schiavoni, S. (2015). A review of unconventional

sustainable building insulation materials. Sustainable Materials and Technologies, 4,

1-17.

ASHRAE, A. (2016). ASHRAE Standard 62.1‐2016, Ventilation for Acceptable Indoor

Air Quality. American Society of Heating, Refrigerating, and Air-Conditioning

Engineers, Inc.: Atlanta, GA.

ASHRAE, Handbook. (2005). Fundamentals volume of the ASHRAE Handbook. In:

Atlanta, GA, USA.

57

Balaras, C. A., Dascalaki, E., & Gaglia, A. (2007). HVAC and indoor thermal conditions

in hospital operating rooms. Energy and buildings, 39(4), 454-470.

Boverket. (2018) Boverket s mandatory provisions and general recommendations,

BBR [Online] Available:

https://www.boverket.se/globalassets/publikationer/dokument/2019/bbr-2011-6-tom-

2018-4-english-2.pdf [Accessed on 15 Apr, 2020]

Boverket. (2020) Energy performance certificate. [Online] Available:

https://www.boverket.se/en/start/building-in-sweden/developer/inspection-and-

delivery/energy-performance-certificate/ [Accessed on 17 Apr, 2020]

Boverket. (2020) Search and order an existing energy declaration. [Online] Available:

https://www.boverket.se/sv/energideklaration/sok-energideklaration/ [Accessed on 17

Apr, 2020]

Cao, X., Dai, X., & Liu, J. (2016). Building energy-consumption status worldwide and

the state-of-the-art technologies for zero-energy buildings during the past decade.

Energy and buildings, 128, 198-213.

Chaudhuri, T., Soh, Y. C., Bose, S., Xie, L., & Li, H. (2016). On assuming Mean Radiant

Temperature equal to air temperature during PMV-based thermal comfort study in air-

conditioned buildings. Paper presented at the IECON 2016-42nd Annual Conference

of the IEEE Industrial Electronics Society.

Cheung, T., Schiavon, S., Parkinson, T., Li, P., & Brager, G. (2019). Analysis of the

accuracy on PMV–PPD model using the ASHRAE Global Thermal Comfort Database

II. Building and Environment, 153, 205-217.

Dave Moser. (2014) Thermal Comfort: More Than Just Air Temperature [Online]

Available: https://www.hpac.com/heating/article/20927877/thermal-comfort-more-

than-just-air-temperature [Accessed on 15 Apr, 2020]

de Dear, R., & Brager, G. S. (1998). Thermal adaptation in the built environment: a

literature review.

Dombaycı, Ö. A. (2007). The environmental impact of optimum insulation thickness for

external walls of buildings. Building and Environment, 42(11), 3855-3859.

Engineering toolbox. (2020). Carbon Dioxide Concentration - Comfort Levels [Online]

Available: https://www.engineeringtoolbox.com/co2-comfort-level-d_1024.html

[Accessed on 15 Apr, 2020]

Fanger, P. O. (1970). Thermal comfort. Analysis and applications in environmental

engineering. Thermal comfort. Analysis and applications in environmental engineering.

Fanger, P. O., Melikov, A. K., Hanzawa, H., & Ring, J. (1988). Air turbulence and

sensation of draught. Energy and buildings, 12(1), 21-39.

58

Fisk, W. J. (2002). How IEQ affects health, productivity. ASHRAE journal, 44(LBNL-

51381).

Gagge, A. P., & Gonzalez, R. R. (2010). Mechanisms of heat exchange: biophysics

and physiology. Comprehensive physiology, 45-84.

GBPN. (2020) Sweden: Summary [Online] Available:

https://www.gbpn.org/databases-tools/rp-detail-pages/sweden#Summary [Accessed

on 15 Apr, 2020]

Gjoko K. (2019). "I Own Your Building (Management System)". Applied Risk. [Online]

Available: https://www.exploit-db.com/docs/47646 [Accessed on 14 Apr, 2020]

Gorse, C., Johnston, D., & Pritchard, M. (2012). A dictionary of construction, surveying,

and civil engineering: Oxford University Press.

Guenther S. (2019). What is PMV? What is PPD? The basics of thermal comfort.

[Online] Available: https://www.simscale.com/blog/2019/09/what-is-pmv-ppd/

[Accessed on 15 Apr, 2020]

Hossain, M. F. (2018). Sustainable Design and Build: Building, Energy, Roads,

Bridges, Water and Sewer Systems: Butterworth-Heinemann.

Housh W. (2017). What is the Ideal Humidity Level for Your House? [Online] Available:

https://www.hvac.com/faq/recommended-humidity-level-home/ [Accessed on 15 Apr,

2020]

Hui, P., Wong, L., & Mui, K. (2008). Using carbon dioxide concentration to assess

indoor air quality in offices. Indoor and Built Environment, 17(3), 213-219.

Humphreys, M. A., Nicol, J. F., & Raja, I. A. (2007). Field studies of indoor thermal

comfort and the progress of the adaptive approach. Advances in building energy

research, 1(1), 55-88.

Hung, S.-S., Chang, C.-Y., Hsu, C.-J., & Chen, S.-W. (2012). Analysis of building

envelope insulation performance utilizing integrated temperature and humidity

sensors. Sensors, 12(7), 8987-9005.

International Organization for Standardization. (2005). Ergonomics of the thermal

environment — Analytical determination and interpretation of thermal comfort using

calculation of the PMV and PPD indices and local thermal comfort criteria (ISO

7730:2005) [Online] Available: https://www.sis.se/api/document/preview/907006/

[Accessed on 15 Apr, 2020]

Jagschies, G., Lindskog, E., Lacki, K., & Galliher, P. M. (2018). Biopharmaceutical

Processing: Development, Design, and Implementation of Manufacturing Processes:

Elsevier.

59

Johansson, D., Bagge, H., & Wahlström, Å. (2018). Cold Climate HVAC 2018:

Sustainable Buildings in Cold Climates: Springer.

Jones, A. P. (1999). Indoor air quality and health. Atmospheric environment, 33(28),

4535-4564.

Kaynakli, O. (2012). A review of the economical and optimum thermal insulation

thickness for building applications. Renewable and Sustainable Energy Reviews,

16(1), 415-425.

Kayo Genku. (2018). Architectural Aspect in the Built Environment, Kungliga Tekniska

högskolan, Stockholm.

Kingspan. (2013). Therma TR20 Roof Board: High performance insulation for flat roofs.

[Online] Available: http://www.kingspaninsulation.eu/PDFs/Therma-TR20-Roof-

Board-Export-June-2013.aspx [Accessed on 20 Apr, 2020]

Klima-der-erde. (2020). Effective climate classification. [Online] Available:

http://www.klima-der-erde.de/koeppen.html [Accessed on 17 Apr, 2020]

Kolokotroni, M., Ren, X., Davies, M., & Mavrogianni, A. (2012). London's urban heat

island: Impact on current and future energy consumption in office buildings. Energy

and buildings, 47, 302-311.

Kritikou, S. K. (2018). Evaluation of acoustic, visual and thermal comfort perception of

students in the Educational Building at KTH Campus: A study case in a university

building in Stockholm.

KTH. (2020). Academic Year Overview. [Online] Available:

https://www.kth.se/en/student/schema/lasarsindelning [Accessed on 17 Apr, 2020]

KTH. (2020). Search Schedules. [Online] Available:

https://www.kth.se/en/student/schema [Accessed on 17 Apr, 2020]

Lyles, W. B., Greve, K. W., Bauer, R. M., Ware, M. R., Schramke, C., Crouch, J., &

Hicks, A. (1991). Sick building syndrome. Southern medical journal, 84(1), 65-71, 76.

Maroni, M., Seifert, B., & Lindvall, T. (1995). Indoor air quality: a comprehensive

reference book: Elsevier.

Meir, I. A., Garb, Y., Jiao, D., & Cicelsky, A. (2009). Post-occupancy evaluation: an

inevitable step toward sustainability. Advances in building energy research, 3(1), 189-

219.

Miller, N., Pogue, D., Gough, Q., & Davis, S. (2009). Green buildings and productivity.

Journal of Sustainable Real Estate, 1(1), 65-89.

Mujeebu, M. A. (2019). Introductory Chapter: Indoor Environmental Quality. In Indoor

Environmental Quality: IntechOpen.

60

Nagy, B. (2014). Comparative analysis of multi-dimensional heat flow modeling. Paper

presented at the Proceedings of the Second International Conference for PhD

Students in Civil Engineering and Architecture: Full papers. Place and date of

conference: Cluj-Napoca, Romania.

Nilson H. (2018) Occupant behavior and building performance, Kungliga Tekniska

högskolan, Stockholm.

O’Sullivan, D., Keane, M., Kelliher, D., & Hitchcock, R. J. (2004). Improving building

operation by tracking performance metrics throughout the building lifecycle (BLC).

Energy and buildings, 36(11), 1075-1090.

Pavel, C., & Blagoeva, D. (2018). Competitive landscape of the EU’s insulation

materials industry for energy-efficient buildings. Publications Office of the European

Union: Luxembourg.

Pérez-Lombard, L., Ortiz, J., & Pout, C. (2008). A review on buildings energy

consumption information. Energy and buildings, 40(3), 394-398.

Persily, A. K. (1997). Evaluating building IAQ and ventilation with indoor carbon dioxide

(0001-2505). Retrieved from

Sarbu, I., & Sebarchievici, C. (2013). Aspects of indoor environmental quality

assessment in buildings. Energy and buildings, 60, 410-419.

Schiavoni, S., Bianchi, F., & Asdrubali, F. (2016). Insulation materials for the building

sector: A review and comparative analysis. Renewable and Sustainable Energy

Reviews, 62, 988-1011.

SGBC. (2020). Miljöbyggnad: Swedish environmental certification for Swedish

conditions. [Online]. Available: https://www.sgbc.se/certifiering/miljobyggnad/

[Accessed on 14 Apr, 2020]

Shah, D. J., Krueger, J. H., & Strand, R. L. (1994). Indoor climate controller system

adjusting both dry-bulb temperature and wet-bulb or dew point temperature in the

enclosure. In: Google Patents.

Shahzad, S., Calautit, J. K., Hughes, B. R., Satish, B., & Rijal, H. B. (2019). Patterns

of thermal preference and Visual Thermal Landscaping model in the workplace.

Applied Energy, 255, 113674.

SKANSKA. (2020). Energy Consumption in Office Buildings: a Comparative Study.

[Online] Available: https://www.skanska.pl/4a58d8/siteassets/oferta/biura/raporty-i-

standardy/raport-zuycia-energii-w-budynkach-biurowych/energy-consumption-in-

office-buildings-report.pdf [Accessed on 15 Apr, 2020]

SLB. (2020). Historical data [Online] Available: http://slb.nu/slbanalys/historiska-data-

met/ [Accessed on 18 Mar, 2020]

61

Standard, I., & ISO, B. (1998). Ergonomics of the thermal environment—Instruments

for measuring physical quantities.

Styrportalen. (2020) Om Styrportalen. [Online]. Available:

https://www.styrportalen.se/about [Accessed on 17 Apr, 2020]

Sweden. (2020) Energy use in Sweden [Online] Available:

https://sweden.se/nature/energy-use-in-sweden/ [Accessed on 15 Apr, 2020]

Swegon Air Academy. (2013). Miljöbyggnad [Online] Available:

https://www.swegonairacademy.com/wp-content/uploads/2013/01/3.pdf [Accessed on

15 Apr, 2020]

Thermal Engineering, (2020). What is Thermal Insulation – Thermal Insulator –

Definition [Online] Available: https://www.thermal-engineering.org/what-is-thermal-

insulation-thermal-insulator-definition/ [Accessed on 15 Apr, 2020]

Thomas, L. C. (1993). Heat transfer: professional version: Prentice-Hall.

Timeanddate. (2020). Past Weather in Stockholm, Sweden — February 2020. [Online]

Available:

https://www.timeanddate.com/weather/sweden/stockholm/historic?month=2&year=20

20 [Accessed on 20 Apr, 2020]

Toftum, J. r., Melikov, A., Tynel, A., Bruzda, M., & Fanger, P. O. (2003). Human

response to air movement—Evaluation of ASHRAE's draft criteria (RP-843). Hvac&R

Research, 9(2), 187-202.

Tsai, D.-H., Lin, J.-S., & Chan, C.-C. (2012). Office workers’ sick building syndrome

and indoor carbon dioxide concentrations. Journal of occupational and environmental

hygiene, 9(5), 345-351.

Tyler Hoyt, Stefano Schiavon, Federico Tartarini, Toby Cheung, Kyle Steinfeld, Alberto

Piccioli, and Dustin Moon. (2019) CBE Thermal Comfort Tool. Center for the Built

Environment, University of California Berkeley. Berkeley, California.

USGBC. (2020). What is WELL? [Online]. Available:

https://www.usgbc.org/articles/what-well [Accessed on 14 Apr, 2020]

USGBC. (2020). LEED rating system. [Online]. Available: https://www.usgbc.org/leed

[Accessed on 14 Apr, 2020]

Wikipedia. (2020). Stockholm: Climate [Online] Available:

https://en.wikipedia.org/wiki/Stockholm#Climate [Accessed on 17 Apr, 2020]

Widström T. (2018). Thermal loads, Kungliga Tekniska högskolan, Stockholm.

Widström T. (2018). Control Systems, Kungliga Tekniska högskolan, Stockholm.

www.kth.se

TRITA-ABE-MBT- 20408