Proceedings of International Conference: Sustainable built environment in thetropics: New technology, new behaviour? School of Architecture, TarumanagaraUniversity, Jakarta, Indonesia, 12-13 November 2012.

OPTIMATION OF BIPV EFFICIENCY BY FOLDINGARCHITECTURE AND USERS BEHAVIOUR IN OFFICE

BUILDING AT SURABAYA

Susan[1], Ir. I Gusti Ngurah Antaryama, PhD. [2], Dr. Ir. V.Totok Noerwasito, M.T.[3]

[1]Student of Master Degree Architecture, ITS[2][3]Lecturer of Master Degree in Architecture Department, ITS

Abstract

The work of BIPV system usually measured by its efficiency. In order to make higher efficiency, effort should be taken to rise electricity output and to reduce electricity demand. Electricity output generized by BIPV depends on the amount of solar radiation received by PV panel. There are some factors affect the amount of radiation received. One of them is the tilt angle and the orientation angle of PV panel. This research try to rise electricity output by collaborating this factor with orientation principle in folding concept. The collaboration results in bigger surface area to receive radiation. Experiment with simulation as it tools will be used as research method to getthe optimal configuration of Folding-BIPV. Meanwhile, the reducement of electricity demand will be described in relation with users behaviour, both individual behaviour and communal behaviour. As the object taken in this research is an office building, communal behaviour will take more impact to reduce energy demand. Policies and strategies related to energy efficiency made by central operational management in office building will control communal behaviour.

Keywords: BIPV, efficiency, folding, individual and communal behaviour, office, orientation.

1. IntroductionEnergy production commonly described as separated

part from the built environment, with large scale powergeneration, and located some distance from the end user(Pitt, 2004)[1]. These cause a number of consequences, suchas the lost of energy used in distribution progress and lowawareness of the user from effects of the use to pollution,

damage to local ecology, and intrusion into the landscape.Facing those kind of issues, architects are concerned tomake a new concept of building design which can maximizethe use of renewable energy, reduce energy demand, as wellas being the energy source itself which can produce energyin the nearest place to the end user.

Energy generation (heat or electricity) by individualbuildings or small groups of buildings at the small scalecan be defined as microgeneration. Microgeneration createsopportunities that bridges the divide between supply anddemand, and also opportunities for consumers to become moreaware of their energy use and its impacts, (Bahaj et al,2006)[2]. Previous study of microgeneration and userbehaviour in the UK domestic sector reported an estimated6% reduction in overall electricity use and evidence wasseen of an increase in general energy awareness and the useof efficient lighting (Keirstead, 2007) [3]. This provesthat users are no longer restricted to being passiverecipients of electricity, but as potentially activeparticipants that have contribution in determining theefficienct of microgeneration technology.

One of promising microgeneration technology isphotovoltaic. PV panels produce the very high-grade energyof electricity, without any pollution, from abundantrenewable resources, solarlight (Lechner, 2009) [4]. Thedirect benefits is clearly one of sustainable electricalpower generation can make financial savings. Indirectbenefits are more subtle and spand softer issues such aspride in building and increased users energy awareness.Efficiency of PV panels measured by output of electricitygeneration compared to electricity demand. In order toachieve higher efficiency, output of electricity generationshould be higher and higher, while electricity demandshould be lower and lower. High electrical demand shouldideally be operated at the peak of solar day.

One of its system called BIPV (Building IntegratedPhotovoltaic) gives more advantages such as reducing cost.The use of PV panels as building envelope will substitudethe need of conventional building’s material. BIPV refersto the application of PV in which the system, as well ashaving the function of producing electricity, also takes on

the role of building form and elements. One of interestingsolution from BIPV application is the use of huge verticalfacade in mid and high-rise building at urban area. Infact, the use of vertical facade is associated with theavailability of huge vertical area compared to horizontalarea (roof). The vertical installement might causeradiation supply is not maximal, but huge facade isexpected to compensate power reduction.

The work of BIPV system as potential renewabletechnology depends on the amount of radiation that reach PVcell, factors related to PV cell, and factors related toarchitecture itself. The last means that the architectureform will influence the efficiency of BIPV, and BIPV willinfluence the form of architecture. One of architecturalapproach to create architecture forms is folding design.Folding architecture has the essence of orientation. Infolding architecture, orientation can be arranged based ondesign needs (Crosbie, 2004) [5]. Meanwhile, in BIPV theoptimal orientation of PV panels take the big role indetermining the output of electricity generation. Based onorientation principle in folding architecture as well as inBIPV, folding architecture can be used as form giver toBIPV. Determination of PV panels and folding orientationcan be arranged to get the optimal radiation. In theorientation arrangement, there is an essence of intervalfolding angle on the building envelope. Folding process andangle interval will create big area of building envelope.Big area of building envelope will add radiation receivingsurface compared to architecture without folding.

Fig. 1. Folding Design at Neo Solar Power Office

(http://inhabitat.com/neo-solar-powerheadquarters-has-a-striking-bluefacade, downloaded on November, 29th, 2011)

[6].

Fig. 2. PV Panel Installation at Public Building withoptimum tilt angle and fixed orientation (Benemann, dkk,

2001: 351) [7].

Temporary opinion, optimation of BIPV electricgeneration can be reached by folding architecture. But asmention before, beside of trying to make the output ofelectricity generation higher, BIPV efficiency will also beinfluenced by electricity demand. As electicity demandbecome lower, the BIPV efficiency will become higher. Inrelation with electricity demand, this paper will discussabout various possibility to reduce it through usersbehaviour. Within office building, there are so many userswith so many variations of behaviour. Doing research onsuch case will be too complex. In fact, in office buildingthere would be a centralized setting managed by operationalmanagement. Moreover, now it is completed with sensor forautomatic control especially for lighting, water system andAC. This research will describe various possibility inreducing energy demand through individual and communalusers behaviour.

The paper therefore has two aims. The first is tocalculate the radiation amount received by foldingarchitecture, in which the folding orientations are

arranged based on BIPV need. This first calculation isrelated to the effort of making higher BIPV electricgeneration. To get through the first aim, research will bedone experimentally with simulation as it tool. Treatmentwill be done by making wall folding configuration based onsolar’s azimuth angle and roof folding configuration basedon solar’s altitude angle. Another factors related to BIPVsuch as PV cell’s temperature, cells number in one modul,silicon type and cell color, shading, number of dioda, WWRwill be isolated. The second aim is to describe annualenergy consumption under different energy-savingenhancement policies and strategies in order to make lowerelectricity demand.

2. Discussion2.1 Optimizing BIPV Electric Generation through Folding

ArchitecturePV cell made from semiconductor material, silicon

(Si). In generating electricity, there are some influencingfactors. First, the cell’s temperature. PV cells can bemaximal in generating electricity at temperature of 25°Cand receiving 1000W/m² solar radiation. An air gap can beused to prevent the rising of PV cell’s temperature (GeunYoung Yun, et al, 2006: 383) [8]. Secondly, PV cells numberin a modul. This will directly influence the voltage ofelectricity generated by PV cells. Commonly, the standardmodul range between 36 until 216 cells. For 36 cells panel,the modul size is 1184 mm x 545 mm x 35 mm. Third, silicontype and PV cell’s color. Monocrystalline Silicon has thehighest efficiency. Usually, PV cell has dark color inorder to minimize light reflection and maximize theelectricity generation.

Fig. 3. Modul of 36 cells PV panel by Bell

(powerbell.indonetwork.co.id, downloaded on April, 17th,2012) [9]

At BIPV system, PV cells commonly placed as buildingenvelope and become an integrated part of the building. Asan integrated part of the building, the building’s formwill influence the efficiency of BIPV. Surface to volumeratio will be an indicator wheteher the building willminimize or maximize radiation received. At BIPV case,solar radiation want to be received as much as possible.Brown (1990: 106) [10] explained that with the same volume,radiation received by long shape buildings will be a lotmore than compact buildings. Markus & Morris (1980)[11] givethat a 2:2:16 building proportion has a good surface tovolume ratio in receiving solar’s radiation. Sometimesbecause of building’s form, radiation received can’t bemaximized. Losing energy for about 10% is assumed as goodcompromize between shape and BIPV function (Urbanetz, etal, 2011) [12]. Another factor related to BIPV efficency isshading. Self shading and environment shading will reducethe electricity output. Environment shading will reducepower output from BIPV up to 40%-60% from its maximumability (Urbanetz, et al, 2011)[12]. Meanwhile for self-shading, Ubisse, et al (2009) [13] explained that using 6dioda in one single panel will minimize the effect of selfshading. Optimal proportion between transparant materialsand opaque PV moduls to total facade area is another factorthat should be concerned when analyzing BIPV efficiency. In

area with strong radiation, the optimal proportion rangebetween 30%-40% (Geun Young Yun, 2006) [8].

Combination of tilt angle and orientation angle willdefinetely influenced BIPV system, both as architecturalform giver and electricity generation. In this paper, thecombination of tilt angle and orientation angle will createfolding-BIPV. As general rules, optimal tilt angle is equalto latitude angle. But for area with low latitude, low tiltangle won’t be too effective since there will be dustcovering the PV surface. Research done by Hussein, et al(2003) [14] found that for area with low latitude, optimumtilt angle range between 20°-30° and optimum orientationangle range between -15° and 15° facing equator.

Fig. 4. Illustration of Tilt Angle for PV Panel (www.bipv.ch/, downloaded on February, 12th, 2012) [15]

2.1.1Research Experiment PlanningPretest, treatment, and posttest condition are shown

in the table below.

Table 1. Experiment Method

Pretest Treatment PosttestConfiguration of solar radiation heat gain building.

1. Configuration of folding roof with10°-15º interval based on solar’s altitude angle.

2. Configuration of folding wall with10°-15º interval based on solar’s altitude and

1. Variation of folding roof configuration.

2. Variation of folding wall configuration.

3. Configuration ofoptimum folding facade.

azimuth.3. Configuration of

folding roof and wall with optimumsurface area and optimum radiationreceived.

2.1.2Model and EvaluationBase case model for pretest condition arranged based

on these theories: Tipology of building for solar radiation heat gain with

2:2:16 proportion (Markus & Morris, 1980) [11]

Floor to floor height for office building is about 4m –4.2m (Kohn and Katz, 2002) [16]

Based on theories above, pretest model dimention are:Height = 16 x 4.2m = 67.2 mLength = 2x4.2m = 8.4 mWidth = 2x4.2m = 8.4 m

Fig. 5. Pretest Model

Folding model for roof and wall with variouspossibility of tilt and orientation angle are arrangedbased on these theories: Pretest Model as shown in Fig. 3. Various possibility of optimum tilt and orientation

angle based on solar’s azimuth and solar’s altitude.

Folding roof configuration based on solar’s altitude and10°-15° interval (Hussein, et al, 2004)[14] placedbetween 10º-75º (for North orientation), 3º-71º (forSouth orientation), 3°-75º (for East orientation), 10º-78° (for West orientation).

Folding wall configuration based on solar’s azimuth and10°-15° interval (Hussein, et al, 2004)[14] placedbetween 273º-85º (for North orientation), 93º-264º (forSouth orientation), 26°-135º (for East orientation),224º-333° (for West orientation). Folding wallconfiguration based on solar’s altitude and 10°-15°interval (Hussein, et al, 2004)[14] placed between 10º-75º (for North orientation), 3º-71º (for Southorientation), 3°-75º (for East orientation), 10º-78°(for West orientation).

36 cells PV panel modul, with its size of 1184 mm x 545mm x 35 mm.

Placement of PV panel on both side of folding shape tominimize electricity variation output.

Totally, there are 27 models for folding roof based onsolar’s altitude, 40 models for folding wall based onsolar’s azimuth, and 27 models for folding wall based onsolar’s altitude. Some of folding models are shown in Table2.

Table 2. Various possibility of Folding Roof and Wall

TREATMENT

1

No.

SolarALT (°)

TILTANGLEof PVpanel(°)

MODELNorth

(N) –

South

(S)

Top view Side view Perspective

1. Folding roofconfiguration with

Au

1

10 80

tilt angle based on solar’s altitude.

Au

222 68

Au

335 55

2. Folding wallconfiguration withorientation angle based on solar’s azimuth

No

.

Solar

AZI

(°)ORIENT

ATION

ANGLE

of PV

panel

(°)

MODEL

North

(N)

Top View

Perspective

Du

1273 87

Du

2292 68

Du

3302 58

Overall, from 27 models of folding roof, biggest area of103,896m² are gained for folding with tilt angle of 45°.This area is 51% bigger than the flat roof (based onpretest model, roof without folding can accomodate PV panelfor 68,69094m² only). For 67 models of folding wall,biggest area of 443,2896m² are gained for folding withorientation angle 135°, 224°, and 314°. This area is 43%bigger than the flat wall (based on pretest model, wallwithout folding can accomodate PV panel for 310,30272m²only). The models are first minimized by this criteria.Secondly the models are minimized by the criteria ofoptimum tilt and orientation angle. From those twocriterias, we choose 7 folding roof models and 3 foldingwall models. Those models and their details are shown inTable 3.

Table 3. Selected ModelsName Orientati

onSolar altitude (°)

Tilt angle (°)

Total surface area(m²)

Flat roof - 90 0 68,69094Folding roof 1

North-South

45 45 103, 896

Folding roof 2

North-South

66 24 91,4285

Folding roof 3

South-North

58 32 91,4285

Folding roof 4

East-West 41 49 98,3549

Folding roof 5

East-West 65 25 91,4285

Folding roof 6

West-East 44 45 103,896

Folding roof 7

West-East 65 25 91,4285

Name Orientation

Solar azimuth (°)

Orientationangle (°)

Total surface area(m²)

Flat wall - - - 310,30272Folding wall 1

North 314 46 443,29

Folding wall 2

East 54 36 398,961

Folding wall 3

West 332 64 398,961

These models are then simulated using Archipaksoftware. This software has the ability to calculate amountof annual radiation received on average day of 12 months,on a sloping surface. Annual radiation received means totalradiation received for 12 months a year. The number oftotal radiation received for each month includeaccumulation of average radiation received in hours perday and days per month. This paper presents preliminarycalculation using climate data of Surabaya 2011 for east-west folding roof and for north folding wall only. Fromthis calculation, preliminary conclusion about folding-BIPVcan be seen. Compared to non-folding roof, total annualradiation received by east-west folding roof are 10% to 32%higher. While for folding wall, the annual radiationreceived is 40% higher than flat wall with east or westorientation. The results of calculation are shown in Table4.

Table 4. Preliminary Calculation for Total Annual RadiationReceived by Folding Roof

Name Orientation

TiltAngle

Surface 1

AnnualRadiati

onReceive

d

Surface 2

AnnualRadiati

onReceive

d

TotalAnnualRadiati

onReceive

d

(°) (°) (m²) (kWh/m²)

(kWh/m²)

(kWh)

Flat roof 0 0 68,690

94 1027 - - 70.545,6

Folding roof 4

East-West 49 51,948 876 46,406

88 912 87.829,52

Folding roof 5

East-West 25 62,337

6 983 29,09088 790 84.259,

13

Folding roof 6

West-East 46 51,948 892 51,948 900 93.090,

82

Foldi West- 25 29,090 983 62,337 790 77.843,

ng roof 7

East 88 6 044

Table 5. Preliminary Calculation for Total Annual RadiationReceived by Folding WallName Azimut

hAngle

OrientationAngle

Surface 1

AnnualRadiati

onReceive

d

Surface 2

AnnualRadiati

onReceive

d

TotalAnnualRadiati

onReceive

d

(°) (°) (m²) (kWh/m²)

(kWh/m²)

(kWh)

Flat wall 0 0 310,

30272 635 - - 197.042,23

90 90 310,30272 648 - - 201.076

,16

270 270 310,30272 648 - - 201.076

,16Folding wall

46 314 221,6448 635 221,64

48 637 281.932,19

2.2 Minimizing BIPV Electric Demand through UsersBehaviour

As mentioned before, in order to make a higher BIPVefficiency, there are various possibility to reduce energydemand based on consumer’s behaviour. At office building,users behaviour more or less will be determined by centraloperational management. This paper will discuss it bydescribing the previous studies and recent governmentpolicies.

2.2.1Previous Studies of PV and Users BehaviourMostly, previous studies related to PV as

microgeneration technology and consumers behaviour tookhousing as their case study. Recent literature suggestthat the most interesting aspects of consumer behaviouroccur once the technologies are installed within the home(Kierstead, 2007)[3]. A review of best practice with PV inEurope notes briefly that adopting households loweredtheir overall electricity demand. Dobbyn and Thomas (2005)[17], make a research about behaviour responsibility both to

those who choose to install the technologies and those whohappened to live in microgenerating homes but were notactively involved in purchasing. The research found thateven the second group has significant increase in theirawareness of electricity use. Producing electricity in thesame place as it is used provided concerned individualswith a way to take responsibility for the environmentalimpact of their lifestyles. In this case, psychologicalfactors take contribution in suggesting that PV is part ofa personally-motivated environmentally-aware lifestyle.Research done by Keirstead (2007)[3] found that respondentsgenerally saw themselves as home energy-savers (defined byinterest in energy bills and do-it-yourself repairs). Whenrespondents were asked to estimate their overallelectricity saving since the installation of PV, it isfound that overall saving are about 5,6%. This number wasseen as an increase in general energy awareness and theuse of efficient energy.

Research made by Bahaj and James (2006)[2] try toshow the relation between PV and occupier behaviour onsocial housing at UK. The result shows that PV has anadded value in terms of demand reduction and contribute toa reduction of fuel poverty. This reduction related to anychanges in consumption by occupier behaviour. The resultshighlight a close correlation between occupant behaviourand energy consumption. Bahaj and James (2006)[2] alsoshows that PV will give more financial benefit whenoperating high demand electrical appliances at the peak ofthe solar day. This research focuses at building office.As in the office, electrical demand from the users willoccur at office hours (9:00-17:00). Meanwhile, the solartime available around 6:00 – 17:00. This will give morebenefit as the electricity demand occur in the range ofsolar time. Bahaj and James (2006)[2] also show that therecan be huge variations in energy demand driven by thebehaviour of the occupants. But in office building, thereis central operational management manage the mechanicalelectrical system. This will give more added value atoffice since energy demand will have less variations.

2.2.2Government Policies and Strategies[18]

At office, users behaviour are determined by centraloperational management. Strategies and policies of centraloperational management more or less will be influenced bygovernment policies. To reduce energy consumption,Indonesian government has made some policies. Thosepolicies are started to be applied especially forgovernment office buildings. As reported on somenewspaper, based on “Instruksi Presiden Nomor 13/2011”, allgovernment offices should reduce the use of energy andwater. Head of Public and Human Resources Department forBUMN, Purwanto on May, 14th, 2012 said that based on SE-01/S.MBU.3/2012, in head office of BUMN, lighting, airconditioning, and elevator machine will be on only from8:00 to 18:00. Aims of this strategy are to reduceelectricity demand for 20% (measured from averageelectricity consumption in 6 months before the instructionissued) and to reduce water consumption for 10% (measuredfrom average water consumption in 6 months before theinstruction issued).

Another government ministry, ESDM, apply strategiesof air conditioning and lighting based on SNI standard. OnFriday, May 4th, 2012, Jarman, General Director ofElectricity, ESDM Ministry, explained that for airconditioning, the temperature range between (25±1)°C. Forlighting, 1m² area should be accomodated by 6 watt LEDlamp or 6 watt HE lamp. These steps are taken bygovernment because of the awareness increase in energyefficiency. By this kind of policy, government hope therewill be a reducement of energy and water consumption.

In relation to this paper, those policies will makeusers behaviour are easier to be controlled, and alsoencourage owner and or central operational management ofoffice building to reduce energy demand. For BIPV system,lower energy demand means a higher efficiency.

3. ConclusionBIPV system has two functions, as an electric

generation technology from renewable resource and also asan architectural form giver. Its efficiency depends on theamount of electricity output and the amount of energydemand. Higher electricity output means higher efficiency,

lower energy demand also means higher efficiency. To actas an architectural form giver and to optimize electricityoutput, this paper focuses on the use of FoldingArchitecture concept through its orientation principle.Comparing surface area between folding and non-folding,there are 51% differences for roof surface and 43%differences for wall surface. For the next step, thisresearch will then be continued by calculating radiationreceived by folding and non-folding surface. Frompreliminary calculation, east-west folding roofs receive22% to 31% higher radiation compared to non-folding roof.

Based on previous research and government policies,it can be said there are two kinds of users behaviour,individual and communal. Previous studies show individualusers behaviour at home increase in energy awareness whenmicrogeneration technology installed. It is shown by thereduction of energy demand into 6%. In office building,there will be more benefit since peak demand happens inrange of peak electricity generation. While communal usersbehaviour means that their behaviour actually determinedby the system and regulation made by building operationalmanagement. When applied strategies and policies arealready aware to energy efficiency, more or less usersbehaviour will have to adapt and compromize. These willdirectly take effect to lower energy demand. As mentionedbefore, lower energy demand means higher efficiency.

Temporary opinion, there will be an increase of BIPVefficiency by optimizing energy output through foldingarchitecture and minimizing energy demand through usersbehaviour.

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