Design and Automation of Passive and Active Systems to a Net Zero Energy School Building

8/6/2019 Design and Automation of Passive and Active Systems to a Net Zero Energy School Building

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Summary - This summary shows a study of a new school building model, developed to enable an energy-efficient and sustainable

building. The bioclimatic framework and the organization of space, allied with the integration of passive techniques, in which

emerges the incorporation of renewable energy, complemented by active ones, creates a high potential of self-sustainability in

buildings. The building automation through passive and active systems, via centralized technique management, led us to create

integration of actuators, with innovative perspectives, in the natural ventilation systems and renewable energy production in

school building. With this proposed model, it is expected a radical change in the way to designing the building, making it possibleto obtain a Net Zero Energy Building balance. This is reflected by the annual balance between demand and supply energy in the

building equal to zero and "Zero" Carbon. It was given particular attention to natural light components and its relationship to

artificial lighting minimization and cooling systems or heating ventilation through air-ground heat exchanger, air collector, cross

effect or chimney effect, ensuring excellent air quality and indoor comfort conditions.

Key words - Energy Building Efficiency, Daylight, Natural Ventilation, Air-Ground Heat Exchanger, Active and Passive Systems,

Centered Technical Management, Renewable Energy, Solar Thermal, Solar Photovoltaic, Net Zero Energy Building

Implementation

This work is carried out to study the implementation a new

school building in Portugal. It was done an energy balance

and, in particular, a building ventilation study usingpassive techniques, of which is the incorporation of

renewable energy, complemented by active ones and

centered technique management, analyzed the high

potential self-sustainability of the building [1]. The wind

action analysis is very important in natural ventilation

characterization. It was used in this sense the values

collected in a meteorological station [2]. To protect the

definition of prevailing winds and decreased temperature

radiant, it was been implemented a live hedge composed

with sheet persistent species (Figure 1) and Tuia, from

Cupressaceas family, has a high evapotranspiration rate,

which regulate and balance the extreme weather

conditions, creating a microclimate. Native species waschosen because of the low porosity achieved in the

implementation of a hedge, reducing wind speed till 90%.

[3] [4] [5]. The space main building has 24 classrooms

with 56 m2

each in two floors. There exists a natural

ventilation system, with a faade air collector with four

openings (automated faade records) in each classroom

section, two 20cm below the floor level and two at the top,

50cm above false ceiling. The air collector (Figure 2) is

composed by 6 PV modules, mounted on an aluminium

structure, arranged in N-S direction and distanced 10cm

from the wall. For this study was selected a particularly

classroom type, (with 56 m2), with a natural ventilation

system. The facade is composed of air collector with four

openings (automated faade records) in each classroom

section, two 20cm below the floor level and two at the top,

50cm above false ceiling. The air collector (Figure 2) is

composed by 6 PV modules, mounted on an aluminium

structure, arranged in N-S direction and distanced 10cm

from the wall. The records of facade implemented here

were developed by [6], the building Solar XXI, taking in

the action guide and left their manipulation to the users.

This study intended to automate its operation, with two

actuators, one linear and one rotation in each record,optimizing its use. A flag is placed in thin glass steer able

in each classroom door, to obtain a cross-ventilation effect.

The flags are open or closed depending on the temperature,

humidity and indoor air quality, compared with outside

temperature and humidity, measured by sensors installed

Design and Automation of Passive and Active

Systems to a Net Zero Energy School Building

Artur Ribeiro1,3

, Joo Ramos1,2

and Jos Baptista3

1Institute for Systems Engineering and Computers at Coimbra, Portugal.

2School of Technology and Management, Polytechnic Institute of Leiria, Portugal.

3Trs-os-Montes e Alto Douro University, Vila Real, Portugal.

E-mail: [email protected]

Figure 1: Protect vegetation scheme in profile of prevailing winds.


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therein. The cross-ventilation effect can be complemented

with the chimney effect, by using the adjacent movement

corridors. They are vertically connected through a duct

across the length and forming a projection on the southern

side of the roof. On this side the ventilation grilles are also

established (Figure 3). The chimney effect can be increased

through a higher temperature in the duct, obtained by

placing a polished aluminium plate liner in the last 2m. The

air ground heat exchanger, allows clean air entrance in the

classroom through concrete pipes buried at 3m. This air

can be used for heating or cooling, depending on the

season, since the conditions of temperature at the burial are

almost constant. These are obvious advantages both

heating and cooling process, being controlled by actuators

on registration circular ventilation ducts. The spread is

produced by fan, that is mounted axially above a metal ring

duct, with 65 cm axis, above the floor, only serving as a

complement to ensure indoor air quality in wind lacksituations on the outside or when CO2 level is achieving the

regulatory limits [7] (Figure 4). The centered technique

management allows to all this automatic manipulation but

only some parameters can be modify by users in a short

period of time, end of witch the management takes control.

The solar thermal system consists of 64 collectors

connected by primary network piping in coverage, is

composed of compound parabolic collectors (CPC) [8],

with 1,99 m2

each, arranged in the E/W direction in its

metal mounting flat roof and with 60 degrees inclination in

order to obtain the maximum return for the winter period

and minimize the gains in July and August. In this period

the hot water needs are virtually nil. This system will be

the main source of heating and DHW Building. On heating

we used two different systems, radiant panels at classrooms

and thermo-ventilation with hot water batteries in services

area and gymnasium at floor 2. This thermo-ventilation is

performed in two steps. The first unit in the treatment of

fresh air (UTAN) [9], the level of coverage, which makes apre-heating to a temperature of 18 C. The second a post-

heating with individual control spaces, which allows a +3

C jump (Figure 5). This measure alone generates energy

savings consumption associated with UTAN [9] operation

Figure 2: Records and PV air collector cut.

Figure 3: Integrated system of natural ventilation and

lighting systems with facade PV air collector and air-

ground heat exchanger.

Figure 4: Detail with front view (left) and cut (right) of

the duct and spread of air-ground heat exchanger system

in floor 0.


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and the use of hot water batteries, whose power stems

primarily from solar thermal system (Figure 6), makes the

heating system extremely economical. The active cooling,

it is expected of marginal use and is intended for floor 2

and floor 1 in the auditorium areas. It is achieved by

installing a cold water battery in UTAN [9], which is

fueled by a chiller compressor with single pump, expansion

vessel and deposit of inertia. This thermo-ventilation is

performed in two steps, the first unit of new air handling(UTAN), which carries a cooling to a temperature of 23 C

and the second, post-heating in areas with individual

control, which allows a jump of +3 C. The cooling output

of the chiller is 22,5 kW, with an input power of 8,74 kW

and an EER of 2,57 [10]. In the gross taxable earnings may

be accounted for all passive systems can contribute to the

heating. In this case were considered as possible

contributing gains introduced in solar thermal heating

systems, radiant floor and thermo-ventilation, earnings for

the air-ground heat exchanger and won by air collector

faade. Solar glazing protection is achieved by using

external blinds with rotatable lamellae [11], allowingdaylight modulation into the interior without creating glare,

minimizing solar gains in summer, through its factor

g=0,09, when in the closed position. In the PV simulation

Figure 6: Solar thermal scheme.

Figure 5: Termoventilation in offices on level 2


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was using the computer program "Sunny Design" [12],

provided by the manufacturer of the drive, SMA, using

Lisbon location, closest existing in the database. For this

system we used two mounting types, an PV air collector

faade, with 180 modules of 190W and 90 of inclination

and another on the gymnasium cover, with 180 modules of

205W, where each line has a inter-distance of 2,5 m and

30 inclination. In the latter type took advantage of the

provision zenith coverage to the South face is required toPV mount and on the North side the daylight introduction

to this space.

Results

The exchange system functioning will be controlled by

centered technique management, by criteria that prevent

interior overheating or under cooling, within the area

served by the current needs, taking advantage of range

temperature between surface and soil to the depth of

underground piping, which on average is 10 C. The flow

of fresh air introduced into building interior by the air-

ground heat exchanger and dissemination of thermal drifteffect by cross-ventilation to hallway duct or air collector

faade, creates the conditions for interior comfort, without

the use of mechanical cooling systems.

In daylight simulation and their integration with the

artificial lighting was used "Dialux" [13] calculation

program and made the energy evaluation according to EN

15193 [14]. In addition to lighting design which

determined the placement of fixtures in order to achieve an

lux average, corresponding to each type of space and its

use, we evaluated the energy systems involved, which is

obtained by weighting the hours of use annual day and

night, combined with economic adjustment, maintenance,

presence, absence, performance, provision of daylight,artificial light control and light transmittance of the glazing

[15] [16]. The "Daylight" regulation [17] [18] [19], which

was implemented in classrooms, will allow an automatic

adjustment in lighting, maximizing natural component

through the interaction of the solar control blinds slat blade

driven [11], the first two spaces.

In Figure 7, we present "Dialux" [13] results calculation, in

a classroom type. The figures represent 100% daylight use

and 100% artificial lighting use, complemented by

daylight. If we consider separately the energy values

calculated by the energy assessment of the Dialux program,

the areas illuminated and non illuminated, have

respectively, 139,62 kWh/year and 180,99 kWh/year, with

LENI [14] corresponding to 3,93kWh/ year.m2 and 9,08

kWh/ year.m2, and the areas of calculation, respectively,

35,51 m2, 19,93 m2 for each classroom. The global LENI[14] is 5,78 kWh/year.m2, much below the limit of 38,1

kWh/year set for this typology. With the coverage final

disposition [20] [21], it was possible that the daylight of

the gymnasium (Figure 8), one gets a better uniformity.

And besides, it was possible the layout of modules on the

surface facing to the south, against an ideal of 30, without

obstruction. These modules in addition to the component

generators, still benefits building, in thermal component,because with a lower U, there is a consequent reduction of

heat losses by coverage. This solution is also more

advantageous for the increase in energy productivity and

also by reducing the inverters loss, as can be confirmed by

the simulations in "Sunny Design" (Figure 9) [12], which

translated into a global energy production of 84372

kWh/year. RSECE [22] calculation in monozone typology

Figure 7:Results of scenario 1 - 100% lighting with

daylight and stage 2 - 100% daylight[13]

Figure 9:Initial result of PV simulation faade system by

Sunny Design of SMA [12]

Figure 8:Gymnasium coverage PV configuration


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was based on the simplified method of global conversion

factor. For these, were esteem functioning hours of each

equipment to building install, were with the respective

powers converted to primary energy, annual consumption

energy was calculated. In this calculation were obtained the

values Cei=-0,01 (kgep/m2.year) and a IEE=-0,01.

Conclusions

This work is carried out to implementation study of a new

school building in Alcobaa, Portugal. Passive technique in

school buildings, which emerges the incorporation of

renewable energy, complemented by active ones creates a

high potential self-sustainability in these buildings [1]. The

air-ground heat exchanger used for heating and cooling

process, is controlled by actuators on record circular duct

ventilation, cannot replace a conventional air conditioning

system, but can provide most of energy need for heating or

cooling at main area of building. The solar chimney is an

extremely useful, especially when applied on the North

side of the greater use of space, including classrooms. This

can satisfy both ventilation processes such as daylight. Theventilation system especially in cooling effect can

effectively replaces the active systems application.

The radiant panels system present in levels 0 and 1, was

chosen for work with low temperatures system. Only then

can integration with power generation by solar thermal

system, the cost profitable, and that in a situation of need to

support the boiler consumption will also be lower, it does

not require a temperature as high. Thermo-ventilation was

considered only for the 2nd floor, given the needs

ventilation type above the levels 0 and 1. The pre and post

treatment air system, both in heating and cooling could be

an efficient method for management of existing resources

against the expected thermal reduced requirements in thisfloor.

The reduction of power generation, resulting from the

photovoltaic system was installed vertically on the faades

were offset, in terms of energy, improving the internal

thermal gains of the classrooms, through the air collector

associated with these structures on the facade. The use of

equipment with high efficiency combined with passive

techniques for heating and cooling, controlled by centered

technical management, have been central to the

achievement of NZEB classification [23]. We managed to

produce a higher overall power consumption of the

building.

The 1st law of thermodynamics, called the "Principle of

Conservation of Energy and the law of Lavoisier, have an

intrinsic relationship. The implementation of NZEB

classification for this building, is a practical demonstration

of application, "In Nature nothing is created, nothing is

lost, everything becomes" more and more and we have to

continue for a Sustainable World.

References

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[19] The lighting handbook; Zumtobell Staff; Lemgo; 2004;

[20] Sick, F.; Erge, T.; Photovoltaics in buildings - A design handbook for

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Design and Automation of Passive and Active Systems to a Net Zero Energy School Building

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