April 2002 ECN-C-02-039

RETROFIT & ARCHITECTURAL INTEGRATION OF PVMODULES IN FAÇADE AND ROOF OF AN OFFICE &

LABORATORY BUILDING, PETTEN

H.F. KaanT.H. Reijenga (BEAR Architecten)`

2 ECN-C-02-039

Abstract

Photovoltaics (PV) should not only be valued as a promising building technology but also as a newchallenge for architectural expression. This has been demonstrated with the renovation of alaboratory building in the Netherlands, constructed in 1963. To achieve a 75% energy saving onbuilding related energy consumption (i.e. heating, cooling, ventilation and electricity use forbuilding operation), the building has been equipped with a PV integrated sunshade system on itssouth façade and roof, while a PV awning has been used for the zone between façade and roof. Thefaçade is covered with 546 PV modules; the awning has 156 modules and the roof 456 modules.The total output of the system is 72 kWp. In total, approximately 620 m2 of PV has been installed,thus saving over 90% of building related electricity consumption (lighting, ventilation, elevators)and over 30% of the total electricity consumption in the building.The project was supported by the EU Thermie programme and by the Dutch Novem NOZ-PVprogramme.

The PV project is a collaboration of the Energy research Centre of the Netherlands ECN, the Dutchutility NUON (former ENW), BEAR Architects of the Netherlands, the Italian architects officeOfficine di Archittetura di Cinzia Abbate, and the Danish manufacturer of sunshade systemsDasolas.

The PV system will be monitored in detail until at least August 2003. ‘Real time’ measuring resultscan be found at http://www.ecntsc/pvdaq4.

Figure 1 The PV integrated sunshading system during the mounting of the module

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CONTENTS

LIST OF TABLES 4

LIST OF FIGURES 4

LIST OF GRAPHS 4

1. INTRODUCTION 5

2. BUILDING RENOVATION IN THE NETHERLANDS: MEETING NEWSTANDARDS 6

3. IMPROVING ENERGY EFFICIENCY BY PV-INTEGRATED SUNSHADESYSTEMS 7

3.1 Energy pattern of the ECN Laboratory Building 73.2 Targets for Energy Savings 8

4. DESIGN AND DEVELOPMENT OF THE INTEGRATED PV-SUNSHADE SYSTEMIN THE FAÇADE, ROOF AND AWNING 11

4.1 Design Constraints of the Façade 114.2 The PV Roofing System 15

5. RESULTS 175.1 The original design plans compared to the final result 175.2 Economic Analysis of the Systems 195.3 Monitoring 205.3.1 Supervision monitoring. 205.3.2 Analytical monitoring. 215.3.3 Preliminary evaluation 215.4 Dissemination 22

6. CONCLUDING REMARKS 25

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LIST OF TABLES

Table 1 Comparison between originally proposed systems and final design 18Table 2 Overview of costs 19Table 3 Calculated energy use before and after renovation 20Table 4 Energy output per inverter in kWh for the combined facade and awning systems, in

the period 1 August 2001 to 1 March 2002. 24Table 5 Energy output per inverter in kWh for the combined facade and awning systems, in

the period 1 August 2001 to 1 March 2002. 24

LIST OF FIGURES

Figure 1 The PV integrated sunshading system during the mounting of the module 2Figure 2 The model at the solar table 12Figure 3 Model measurements in the daylight room 13Figure 4 Visualisation of Building 31 and the three modules of the new Building 42 14Figure 5 Detail of the PV-façade. The catwalk and the aluminium covered steel profiles are

clearly visible 14Figure 6 The PV roof 15Figure 7 Openings in the lamellas for adequate ventilation 15Figure 8 Building the mock-up 16Figure 9 Two rooms in the test situation: the left one with PV-sunshading lamellas (mock-up)

and the right one without lamellas 16Figure 10 ECN Building 31 before renovation 17Figure 11 ECN Buiding 31 completed 17Figure 12 Infrared photo of the lamella facade. The light coloured modules dysfunction 22Figure 13 Visualisation of the envisaged public web-page (in Dutch) 26

LIST OF GRAPHS

Graph 1 Heat demand before renovation 8Graph 2 Temperature excess (above 25 °C) before renovation, 2nd and 4th floors 8Graph 3 Calculated heat demand after renovation 9Graph 4 Temperature excess (above 25 °C) after renovation, 2nd and 4th floor 10Graph 5 Energy output per inverter in kWh for the combined facade and awning systems, in

the period 1 August 2001 to 1 March 2002. 22Graph 6 Energy output per inverter for the roof system, in the period 1 August 2001 to 1

March 2002. 23

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1. INTRODUCTION

Since the energy crises of the 1970s and, even more so, since CO2-reduction has become a worldwide political issue, it is generally realised that in the shorter or longer term fossil fuel generatedenergy has to be replaced by forms of renewable energy. Though not yet economically competitive,photovoltaic conversion of sunlight (PV) is a promising technology for future energy supply. PVintegration in buildings could become a money saving option because it provides easier mountingsystems and saves roofing materials as well as floor space which is a considerable advantage fordensely populated areas such as in Western Europe.

For a laboratory building located on the site of the Energy research Centre of the Netherlands ECNat Petten, the Netherlands, a PV-integrated sunshade system, a PV awning system and a PV roofingsystem have been developed. The project is a collaboration between the Dutch organisations ECN,BEAR Architects, the utility NUON (former ENW), Shell Solar Energy and BP Solar, and theItalian Officine di Archittura Cinzia Abbate from Rome. The Danish company Dasolas wasinvolved in manufacturing the combined PV support/sunshade system. It should be mentioned here,that representatives of ECN, BEAR, ENW, Shell Solar and Officine di Archittetura di CinziaAbbate were participating as experts in IEA Task 7: Photovoltaics in Buildings. The project’sprogress was presented and discussed at the biannual Task 7 Experts Meetings, when the expertsshared their experiences in design, engineering and manufacture and exchanged ideas to stimulatethe further progress of the project.

This report deals with the process and results of developing and designing the PV-integratedsunshade system for the ECN laboratory building (Building 31). This building, built in 1963, hasbeen renovated, the energy performance has been improved and –in relation to that- a large PVcovered sunshading façade, PV awning and PV roof have been constructed. The façade is coveredwith 546 PV modules; the awning has 156 modules and the roof 456 modules. The total output ofthe system is 72 kWp.The project was supported by the EU Thermie programme and by the Dutch Novem NOZ-PVprogramme.

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2. BUILDING RENOVATION IN THE NETHERLANDS: MEETINGNEW STANDARDS

Until the energy crisis in 1973 requirements for energy or thermal insulation were non-existent inthe Netherlands. There was plenty of natural gas, most Dutch buildings were - and still are - gas-heated and energy prices were low. The oil crisis (boycott of oil supply to the Western world by theGulf States) resulted in higher oil prices. Because Dutch gas prices were directly coupled to worldmarket oil prices, the gas price rose in the Netherlands. At once, the Dutch government set upbuilding insulation programmes, and added insulation requirements to building standards. Energysaving became a political issue, fed by the ‘The Club of Rome’ report which warned the world forthe ecological consequences of unrestricted economic growth.

During the 1980s, it appeared that increasingly higher insulation standards were not sufficient tosave energy in non-residential buildings. Due to the growing number of office machines, such ascopiers, computers and coffee machines, higher insulation standards paradoxically caused higherenergy consumption, because during the summer cooling demand increased in spite of the moderateDutch climate.

The Dutch Ministry of Housing, Spatial Planning and Environment, which is responsible forgovernmental buildings in the Netherlands, was the first to recognise the above paradox. To dealwith this problem it developed an energy performance standard and tested it in its own buildings.After evaluation, the standard was added to the building regulations, while an energy performancestandard for residential buildings was simultaneously developed.

It is beyond the scope of this report to discuss the Dutch energy performance standard in detail. Inbrief, it involves a standardised method of calculations that must prove that the energy consumptionfor building related functions does not exceed a defined level. This level depends on the size and thefunction of the building. This means that the architect can vary the shape and the amount ofinsulation material (if not under the required minimum) and other energy saving measures, as longas the energy performance coefficient is not exceeded: the lower the coefficient, the better theenergy performance.

The energy performance coefficient (a number without dimension) is defined in the Dutch nationalbuilding regulations. Because CO2-reduction policy is quite an important issue, both in theNetherlands and in the EU, the coefficient has been lowered every two years since its introduction.More attention for energy conscious design is therefore required from architects and builders.Elements which have a positive influence on the energy performance of a building include balancedventilation with heat recovery, passive solar building, passive and natural cooling, heat and coolstorage, heat pumps and photovoltaics. The Dutch Government has set up extensive stimulationprogrammes for these technologies. In addition, R&D and demonstration of energy efficient designand technologies are encouraged by the EC, who subsidises demonstration projects up to 40 %,such as, for example, the Thermie programme. It may be clear, that these nationally and ECstimulated programmes may challenge principals, architects and engineers to develop buildingswhich set new standards in energy efficiency.

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3. IMPROVING ENERGY EFFICIENCY BY PV-INTEGRATEDSUNSHADE SYSTEMS

ECN is the central energy research institute in the Netherlands, working on renewable energy, fossilfuels, nuclear energy, energy efficiency and energy policy studies. For the different researchprojects and technical support tasks, there are many buildings on the ECN site varying from offices,auditorium and restaurant to laboratories and nuclear reactor. Most of the buildings were erected inthe 1960s and 1970s. Because research programmes, techniques and tools have changed since then,many of those buildings are more or less obsolete by now. A few years ago, a renovation andreplacement programme has been initiated. It will be obvious that new and renovated buildingsalike will have to meet the Dutch Energy Performance Standard for non-residential buildings. Trueto its mission as an energy research centre, ECN will use this opportunity to investigate its ownbuilding stock and, at the same time, develop cost-effective methods to make buildings more energyefficient than prescribed by the current Energy Performance Standard.

One of the buildings that was going to be renovated is the ‘General Laboratory’, a four-storeyedbuilding constructed in 1963 with a total floor surface of 3530 m2. An inspection showed that thebuilding had several major shortcomings. The façades and windows had large thermal leaks, thebreast walls functioned as thermal bridges and the heating and ventilation systems did not functionany more as they should. Insulation of the building was poor – it was built according to thestandards of 1963, when insulation was not required; not until the 1970s the cavity walls wereinsulated. During the summer, the south side of the building suffered from overheating.On the other hand, the support construction of the building was sufficiently strong and the concreteskeleton did not show any signs of decay. For these reasons it was decided to renovate the buildingrather than demolish and rebuilt it. Another fact in favour of renovation was that the currentplanning regulations for the ECN site do not allow the erection of a new building with four storeys.Only a three-storeyed building is permitted, which would mean a 25% loss of floor surface. It maybe evident that renovation of the building was the best option. In addition, energy conservation, theuse of renewable energy and energy efficiency could be demonstrated in the renovated building tothe extent possible.

3.1 Energy pattern of the ECN Laboratory BuildingIn order to define the targets for energy savings in the ECN laboratory building after renovation, theenergy pattern of the building before renovation was measured.

The overall annual electricity consumption of the building was 286,000 kWh, i.e. 80 kWh/m2. Thisis high compared to other buildings dating from the same period. The large number of computers inthe building was responsible for this large consumption together with the inefficient lighting,heating and ventilation systems.

The overall annual heat consumption was 1750 GJ, i.e. approximately 140 kWh/m2, which wouldbe a normal energy consumption for a Dutch building from the 1960s. However, the actual heatdemand was much higher because the heat dissipated in the computers (65 kWh/m2year) was notaccounted for. Graph 1 shows the heat demand for the situation before renovation.

8 ECN-C-02-039

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Graph 1 Heat demand before renovation

Comfort in the building was far from ideal. This was partially caused by shortcomings in the façade(cold in winter) and partially by overheating in summer. According to the current standard in theNetherlands, indoor temperature of buildings should not exceed 25 oC for more than 130 hours peryear. As Graph 2 shows, the situation before renovation could not meet that standard.

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Graph 2 Temperature excess (above 25 °C) before renovation, 2nd and 4th floors

3.2 Targets for Energy SavingsIn 1994 ECN designed and constructed a new office building for the business unit RenewableEnergy, which was for several years the most energy efficient office building in the Netherlands.The heat demand of this building is 50 kWh/m2year. When defining the energy target for thelaboratory building after renovation, it was decided not to exceed this level. Such a target is rather

ECN-C-02-039 9

ambitious, because renovation of an old building entails many more restrictions than construction ofa new building. The electricity demand target should not exceed 40 kWh/m2year, which is 20%below the demand in the office building. These targets do not include energy demand related to thelaboratory processes.

Energy conservation policy in the Netherlands is based on the necessity to reduce CO2 emissions.Hence, reduction of primary fossil fuel consumption for energy generation is an important target. Inthis case, co-generation and application of photovoltaics, though not cost-effective yet, cancontribute substantially to this goal. Simulations with the TRNSYS program showed that thesemeasures, combined with lower energy demand, could reduce primary energy demand to 80kWh/m2year, which is 40% below the earlier-mentioned office building demand. Graph 3 shows thecalculated heat demand after renovation.

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Graph 3 Calculated heat demand after renovation

As previously mentioned, overheating is an important problem. In order to avoid energy swallowingair-conditioners – the building should be cooled by natural ventilation and summer night cooling -heat load should be as low as possible. In addition to efficient office machines and adequateautomatic switch-off appliances, outside sunshade devices should be applied to the extent possible.This requirement is one of the points of departure for the development of the PV system, whichshould be designed as a combined PV support/sunshade system, both on the façade and on the roof.Thus, temperature excess during the summer months can be reduced to far below the standard, ascomputer simulations have shown (Graph 4). In addition, PV will generate a considerable amountof electricity. Approximately 620.5 m2 of PV modules can be applied: 262.5m2 integrated in thefaçade shading device, 283 m2 as a sunshade roof construction and 75 m2 mounted as an awning.The PV system will produce in total 57.7 MWh per year.

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Graph 4 Temperature excess (above 25 °C) after renovation, 2nd and 4th floor

ECN-C-02-039 11

4. DESIGN AND DEVELOPMENT OF THE INTEGRATED PV-SUNSHADE SYSTEM IN THE FAÇADE, ROOF AND AWNING

4.1 Design Constraints of the FaçadeThe design of the integrated PV-sunshade system shows several interesting aspects. As the southfaçade has an overheating problem during the summer, it seems obvious that the PV modulesshould be integrated in the exterior sunshade system. Such a solution may• optimise solar gain for the PV modules• give adequate shading to the building during the summer, thus reducing the heat load• diffuse/distribute incoming daylight• facilitate maintenance of the building and cleaning of the windows (maintenance walkway)• optimise construction costs by the elimination of costs for a conventional PV module support

system.

A choice had to be made whether the shading device should be mounted close to the façade or at acertain distance from it. Furthermore, the size of the lamellas had to be determined: should a few,wide lamellas be preferable to a larger number of slim lamellas? What should be the length of thelamellas?An inventory of building integrated PV projects carried out by the IEA Task 7 experts providedsome interesting examples of PV integrated sunshade systems. Most of the systems seemed to bedesigned from a sunshade aspect. Compared to the available façade surfaces, only small quantitiesof PV were applied. In a few examples the application of PV was optimised. However, two lessonscould be learned from these projects: either the view from the rooms behind the façade wasobstructed by the PV modules or, if not, the PV modules were in a rather shaded position which ofcourse should be avoided.

Methods to avoid the shading of the PV-modules were studied using a 1:10 scale model of an officeroom with different façades (see Figure 3). The model was tested in a daylight chamber and on a so-called solar table. Special attention was given to the shading of the modules, the solar gain, the heatload of the building, the shading of the building, the view from within and daylight conditions.Methods to improve the obstructed view were studied. It seemed a good idea to make the lamellasmoveable at eye level so that a person in the room could move the lamellas in a horizontal positionand then, after some twenty minutes, the lamellas would automatically regain their original 37o tilt.As a result, the appearance of the building would continually change by the moving lamellas, thuscreating an interesting architectural feature.

The study showed that the best results for solar gain, shading and daylight illumination wereobtained by a model using four fixed lamellas per floor. Comparison of the PV yields revealed thatthe yield of a completely moveable system is only approximately 10% higher than that of a fixedsystem.In consideration of the considerable higher cost of a completely moveable system and the rathersmall difference in solar gain, a system was selected with the lamellas fixed in the optimal position(in the Netherlands 37o with the horizon) and one moveable lamella at eye level.

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Figure 2 The model at the solar table

As far as could be predicted from the study, the specific position of the lamellas would improve thedistribution of daylight in the rooms, so that the daylight situation throughout the rooms wouldbecome more even. However, to acquire more insight into the effect of the integrated PV/sunshadesystem on the daylight situation in the rooms, a separate study was desirable. Advanced daylightcomputer simulations with the help of the Radiance program were carried out, followed bymeasurements on a real scale mock up (see Fig. 9 and 10) Not only daylight aspects were examinedby means of the mock-up, but also implications for the construction, deterioration of moveableconstruction parts, manufacturing problems and colour options. Also, the acceptance by the users ofthe building was examined. The idea was that the more time and effort were spent in the prototypestage, the fewer mistakes would be made in the construction stage. This assumption has proved tobe fully right. One important conclusion must be drawn here: a large scale project as this PVintegrated shading system should never be made before testing the visual, physical andconstructional implications with the help of a mock-up.

To facilitate maintenance, accessibility and window cleaning, it was decided to construct theshading/PV device as a separate façade at approximately 80 cm from the building and connected tothe main structure of the building. The length of the lamellas followed from the width of the roomsof the building.

The PV façade consists of thirteen bays of three floors plus ground floor. The bays of the groundfloor are provided with two lamellas each, those of the second to the fourth floor with four lamellaseach. Each lamella is 840 mm wide, 3000 mm long and is covered by three standard multi-crystalline silicon PV modules on the front part. Because of the dimensions of the lamellas, the

ECN-C-02-039 13

building is shaded during the summer period. The efficiency of the shading system is about 85%, aswas proven at the solar table. For fine-tuning the glare of the sun, especially in the winter, a second,very simple interior shading system should be provided. Per floor the lamella at eye level ismovable over its horizontal axis, to provide the users of the space behind a better view.The lamellas are made of folded aluminium that has been powder coated for a larger durability.They are mounted between vertical galvanised steel IPE 120 profiles, which are interconnected withhorizontal IPE 120 profiles. These carry the metal grid for façade maintenance and are fixed on theconcrete floors of the existing building. The metal lamella rear side is provided with openings forgood ventilation of the PV modules. The electric wiring is led in the hollow corps of the lamellas.The vertical steel profiles are covered with aluminium sheet covers clipped on front and back.Under these clipped aluminium covers the vertical wiring is mounted. Along the steel elements thePV façade modules are vertically interconnected to form thirteen subsystems. Each subsystemconsists of an inverter, seven strings with six standard 49 Wp modules each from the lamellas andtwo strings of six transparent 44.4 Wp modules from the awning. All inverters, both for the façade,the awning and the roof, are installed underneath the upper roof, which covers an installation space.

Figure 3 Model measurements in the daylight room

14 ECN-C-02-039

Figure 4 Visualisation of Building 31 and the three modules of the new Building 42

Photo: Marcel van KerckhovenCopyrights: BEAR Architecten, Gouda

Figure 5 Detail of the PV-façade. The catwalk and the aluminium covered steel profiles areclearly visible

ECN-C-02-039 15

4.2 The PV Roofing SystemThe PV roofing system was originally planned as a kind of a parasol: a passive-cooling device forthe roof. The roof construction underneath should provide water tightness. As the interior design ofthe building began to take shape more and more, it became clear that the space between the parasoland the existing roof could be used for technical devices such as ventilators and air ducts. Hence, itwas decided to construct the parasol as a watertight but ventilated part of the building. The PVsupport construction provides water tightness; the frameless PV modules are mounted by means ofsmall square joints (BP Solar Sunflower system).The roof is constructed from curved IPE 240 steel profiles, which carry a corrugated steel sheet. Alayer of rock wool insulation, above which an EPDM foil is placed as a watertight layer, covers thesheet. Above this, standard PV modules are mounted with the BP Sunflower system. The profiles tohold the Sunflower module mounting nuts are fixed on pieces of laminated wood, which are fixedon the IPE 240 profiles with bolts.As it is not possible to walk over this construction, a roof trolley bridge has been installed, to enableeasy maintenance.

The PV roofing system consists of 456 mono-crystalline silicon standard modules with 19 inverters,in 38 strings of 12 modules. The total output of the roofing system is 38.76 kWp.

In the original plans about 100 m2 PV was included for cladding of the staircase wall. During thedesign process, however, ECN decided to have a new building built adjacent to Building 31. Forthis reason, the existing staircase was demolished and replaced by a new staircase with differentorientation. Thus the possibility for applying PV cladding in an appropriate way disappeared. Bycovering the roof with mono-crystalline silicon modules instead of multi-crystalline, the total outputof the systems is more than originally foreseen, thus compensating the left out PV cladding.

Figure 6 The PV roof Figure 7 Openings in the lamellas foradequate ventilation

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Figure 8 Building the mock-up

Figure 9 Two rooms in the test situation: the left one with PV-sunshading lamellas (mock-up) andthe right one without lamellas

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5. RESULTS

5.1 The original design plans compared to the final resultAs stated before, the original design plans differ from the final results. The main difference iscaused by the decision to demolish the staircase and make a new one. A PV cladding system on thenew staircase was not useful anymore. Second change is the application of mono-crystalline siliconmodules in the roof instead of multi-crystalline. This was caused by the desire not to diminish theinstalled total output of the PV project, and because of the fact that changed constructionalrequirements asked for frameless modules. At the time of trading with suppliers, BP modulesseemed to be the cheapest per Wp installed. Those modules were made of mono-crystalline silicon.Third change is the awning that was elaborated more in detail during the project. However, such arefinement during the design process is rather usual in building design processes.

A comparison between originally proposed systems and final design is shown in the table below.

Figure 10 ECN Building 31 before renovation Figure 11 ECN Buiding 31 completed

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Table 1 Comparison between originally proposed systems and final designOriginally proposed Final design

FaçadeModules make and type R&S (Shell Solar) IRS50 Shell Solar RSM 50Number of modules 672 546Nominal peak power per module 50Wp 49 WpTotal peak power of the façadesystem

33.6 kWp 26.75 kWp

Inverters make and type SMA Photovoltaic Inverters Mastervolt 2500Number of inverters 13

AwningModules make and type - Shell Solar IRD 50Number of modules - 156Nominal peak power per module - 44.4 WpTotal peak power of the awningsystem

- 6.9 kWp

Inverters make and type - Mastervolt 2500Number of inverters - Awning system electrically

integrated in façade system

RoofModules make and type R&S (Shell Solar) IRS50 BP Solarex 585-LNumber of modules 516 456Nominal peak power per module 50Wp 85 WpTotal peak power of the roofsystem

25.8 kWp 38,76 kWp

Inverters make and type SMA Photovoltaic Inverters SMA Photovoltaic Inverters, typeBP Sunny Boy 2400

Number of inverters 19

Cladding staircaseModules make and type R&S (Shell Solar) IRS50 -Number of modules 200 -Total peak power proposed 10 kWp -

Total peak power 69.4 kWp 72.4 kWp

ECN-C-02-039 19

5.2 Economic Analysis of the SystemsVisitors often ask “ What are the costs of the PV systems?”This question is more difficult to answer, as seems to be at first sight. The question is how tocalculate the costs. The following approaches could be considered:

1. Costs are defined as the total investment costs to get the PV structure realised. This means:included the costs for architect, engineering, co-ordination, support construction, labour on theelectrical system, etc. The difficulty is, that by definition costs for preparation of a buildingintegrated PV project like the ECN Building 31 cannot be split into a “PV project” part and an“other” part. A normative percentage could be taken, but it is debatable if such a percentagemeets the real situation.

2. Costs are defined as the investment in material, so PV plus support structure. This can be true,but how to calculate for instance the roof construction? The roof construction of the buildingthat should have been built without BIPV is quite a different one compared to the roof structureas it is now. In order to calculate the PV costs, the roof should be redesigned and costscalculated without PV, and distracted from the costs as they finally were.

3. Costs are defined as the net costs, i.e. the costs of the invested materials, minus the costs thatare saved. For instance the costs of an exterior sunshading system and the costs of a coolingdevice may be distracted from the costs of the PV integrated system.

4. Costs could be related to operational costs. But what costs should be taken into consideration?Investment costs –see above. Savings on energy costs: difficult to calculate as the alternative(building without BIPV) is hypothetical; what to do with tariffs of large consumers versus smallconsumers, taxes on energy, subsidies?

Taking the above notes into account in the interpretation, the following economic overview couldbe made.

Table 2 Overview of costsSystem Costs of the system (i.e.

including PV modules, inverters,wiring, installation costs) in €/(NLG)

€/Wp / NLG/Wp

Integrated PV-sunshading facade 181,820 / 400,000 6.66 / 14.65Awning 72,727 / 160,000 10.36 / 22.79Roof 251,555 / 553,422 6.45 / 14.19

Total of systems 509,101 / 1,113,422 6.90 / 15.18

As the eligible costs for the EC Thermie project have been calculated at € 997,024 /NLG 2,193,453,the costs for project preparation, design, management, commissioning, support constructions for thePV systems, reporting, dissemination and monitoring can be calculated at € 487,923 / NLG1,080,031.

This may seem rather much. However, as an integrated system implies both integration into thetotal energy system of the building and visual and technical integration of the PV modules in thesunshading system, the consequences of the PV system for the energy system of the building shouldbe taken into consideration too. In the first place, the integrated PV-sunshading system makes anoutside sunshading system superfluous, which means a reduction of costs of about € 181,820 / NLG400,000. Furthermore, the cooling capacity of the cooling system can be much lower, so that about

20 ECN-C-02-039

€ 113,640 (NLG 250,000) can be saved on investment costs. (As this is a laboratory building, acooling device is still necessary as high temperature experiments are foreseen.) In the third place, anreduction on electricity costs can be expected, as the distribution of the daylight enables workingwithout additional blinds for the greater part of the year, and, as a consequence, without electricallight at the daytime. In combination with daylight sensor operating, the reduction on electric energyconsumption can be calculated as follows (using the TRNSYS computer simulation program):

Table 3 Calculated energy use before and after renovationEnergy for: Before retrofit After retrofit

Heating 1,750 GJ 425 GJBuilding related cooling 25,000kWh 0 kWhInstallations, pumps, ventilators 60,000kWh 30,000 kWhElevator 12,000 kWh 12,000 kWhArtificial lighting* 42,000 kWh 20,000 kWhComputers etc** 145,000 kWh ≤ 122,000 kWh

Total energy consumption 1,750 GJ (100%) + 286,000kWh(100%)

425 GJ (25%) + 184,000 kWh(65%)

* The reduction is obtained by using High Efficiency light fittings and High Efficiency fluorescenttubes. And by the fact that due to the lamella system the daylighting level in the rooms is moresuitable for computer screen working, which makes the use of blinds and, as a consequence,artificial light superfluous.

** Consumption is not building related, the dissipated heat however is important to be considered.

The electricity demand before and after renovation is 81 respectively 52 kWh/m2 per yearThe electricity yields of the PV system are estimated at 57,920 kWh per year. ECN is a large energyconsumer and the kWh price is for large consumers much lower than for small consumers likehouseholds. Therefore the direct economic benefits of the electricity production by the PV system islimited. The benefits lay in reduction of CO2 emissions.

Apart from the above mentioned costs one important other cost factors should be mentioned. TheThermie contract was signed in 1997. Included in the contract was a time schedule. It’s true, that theschedule has certain flexibility, but the internal organisational developments within ECN made it –unforeseen- difficult to work according to the schedule. In order to fulfil the requirements of thecontract and have the building process started and ended in time, an additional € 450,000 had to beinvested in temporary office units. Though this investment should not fully be written off from theproject, the investment should not have been necessary if the time constraints were not that severe.

5.3 MonitoringThe monitoring will start after all PV-systems have been commissioned and will last at least 24months from that date. The monitoring consists of two parts: supervision monitoring and analyticalmonitoring.

5.3.1 Supervision monitoringSupervision monitoring aims at the detection of systems with a sub-optimal performance. For thispurpose all 32 PV-systems have been equipped with individual kWh-meters. Furthermore 8integrating radiation sensors are used in order to validate shading models and for redundancy. Theradiation data and production data of the individual PV-systems are monitored daily.

ECN-C-02-039 21

5.3.2 Analytical monitoring.One PV-system of the roof and one PV-system of the façade are monitored analytically in fullcompliance with the procedures laid down in the documents of the CEC Joint Research CentreISPRA, in the Dutch Guidelines (RC 4154) and in the IEC 61724 standard. Additionally the outputof 9 individual strings of one PV-system on the façade will be monitored for research on shadingeffects.Because the modules have various orientations the irradiance are measured on 8 different positionson the building, as well as the corresponding module temperatures.The data acquisition is performed with a sample frequency of about 1 Hz and the results are storedas averaged data over periods of 10 minutes for subsequent off line evaluation.

5.3.3 Preliminary evaluationAs the monitoring process was in full operation only in August 2001, it is not possible to give afinal evaluation of the monitoring results and the effect that the PV sunshading facade and roof haveon the energy consumption of the building. This will be reported at the end of the year 2003, whenthe PV monitoring and thermal monitoring process has finalised. From a first visual survey can belearned, that the effect of the sunshading system is in accordance with the results of the simulationsThe amount of light seems to be sufficient, whilst an additional, simple indoor sunshading systemhas to be added in order to reduce the sunlight in winter.

About 21 June, when the sun is at its highest, the upper row of PV cells are partially shaded duringmidday, as was foreseen in the design stage. The chosen configuration however is the optimumbetween sunshading and electricity yield over the year.

An energy research centre like ECN is very pleased of course with a PV system like this formonitoring and analysis. In addition to the budget for monitoring that was included in the Thermie-project, a budget is available for extended monitoring activities. The measurements started inAugust 2001. The results will be sent to JRC-Ispra until 2003.

By analysing the yields of the systems weekly it has been found that many of the systems did notwork as they should. The roof system consists of 19 inverters SMA-SunnyBoy 2400. Shortly aftercommissioning of the system, five inverters proved to fail because of deteriorated AC fuses. It wasfound that during switching on the system, very high current peaks could occur (200 Amps througha 10 Amps fuse). The problems have been solved by the manufacturer of the inverters.The lamella facade is provided with 13 inverters Mastervolt SunMaster 2500. One of the invertersseemed to be defect. Sometimes two of the inverters stopped operating for days, without anydetectable reason. The manufacturer of the inverters has solved the problems.Monitoring the functioning of the inverters will continue until August 2003 at least.

Infrared photography offers an interesting opportunity to detect quickly failures in the PV modules.When a cell does not provide electricity for some reason or other, it will become warmer than thecells that produce electricity. An infrared camera can directly detect this. Using this method anumber of modules seemed not to work. This was caused by wrong wiring (interchanging plus andminus connections). The installer has solved the problem.

22 ECN-C-02-039

020406080

100120140160180

8-01 /9-01

9-01 /10-

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nr1nr2nr3nr4nr5nr6nr7nr8nr9nr10nr11nr12nr13

Graph 5 Energy output per inverter in kWh for the combined facade and awning systems, in theperiod 1 August 2001 to 1 March 2002.

This year the building included the PV systems and the environment will be modelled using theSwiss computer programme PVSYST. The monitoring results will be compared to the data of themodel in order to validate PVSYST. Furthermore, the energy losses of the various PV systems willbe quantified.

5.4 DisseminationIn addition to the normal intermediate and final publications in the open literature also a public webpage will be maintained. This web page (in Dutch) shows the momentary power data as well as thetotal energy data obtained over various periods. See http://www.ecntsc/pvdaq4/

.

41.5°C

52.9°C

50

Figure 12 Infrared photo of the lamella facade. The light coloured modules dysfunction

ECN-C-02-039 23

0

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8-01/9-01 9-01/10-01 10-01/11-01 11-01/12-01 12-01/01-02 01-02/02-02 02-02/03-02

nr1nr2nr3nr4nr5nr6nr7nr8nr9nr10nr11nr12nr13nr14nr15nr16nr17nr18nr19

Graph 6 Energy output per inverter for the roof system, in the period 1 August 2001 to 1 March2002.

24 ECN-C-02-039

Table 4 Energy output per inverter in kWh for the combined facade and awning systems, in the period 1 August 2001 to 1 March 2002.

Facade Systems; Energy Output in kWh and irradiation in kWh/m2 and MWhMonth Inverter

nr1 nr2 nr3 nr4 Nr5 nr6 nr7 nr8 nr9 nr10 nr11 nr12 nr13 kWh/m2

MWh

August 01 165,5 88,6 55,4 162,1 156,2 161,6 159,1 155,7 161,9 162,2 156,9 161,4 159,2 92.7 31.3September 01 165,3 91,1 90,7 161,3 158,5 161,4 158,5 158,4 161,7 162,9 160,6 161,5 155,9 87.5 29.6October 01 145,5 80,9 0 143,1 143,2 143,6 138,8 133,8 143,1 143,1 141,4 142,8 0 74.0 25.0November 01 64,9 63,7 59,3 63,9 61,4 63,9 62,2 60,4 63,6 63,7 63,2 63,8 0 33.3 11.2December 01 58,1 58,1 46,6 60,8 51,3 61,3 59,4 50 61,4 61,4 61,1 0 0 31.8 10.7January 02 83,3 81,4 82,1 82,2 82,5 82,5 80 52,9 82,6 82,5 82 0 82,4 40.9 13.8February 02 132,7 130,8 131,4 130,7 131,4 130,2 127,9 14 130,4 130,5 129,5 130,5 129,6 65.4 22.1

Table 5 Energy output per inverter in kWh for the combined facade and awning systems, in the period 1 August 2001 to 1 March 2002.

Roof Systems; Energy Output in kWh and irradiation in kWh/m2 and MWhMonth inverters

nr1 nr2 Nr3 nr4 nr5 nr6 nr7 nr8 nr9 nr10 nr11 nr12 nr13 nr14 nr15 nr16 nr17 nr18 nr19 kWh/m2 MWhAugust 01 0 147,4 145,5 149,8 148,9 148,5 143,5 0 145 147 147,2 143,3 26,6 150,8 148,7 151,4 151,4 145,8 101,7 101.7 29.2September 01 0 142,8 140,7 141,7 35,5 36,3 35,6 138 0 138 141,5 143,1 139 63,3 142,8 141,9 145 143 129,6 90.3 26.0October 01 0 99,4 100,4 100,5 0 0 0 97,1 0 97,7 99,8 101,2 98,7 55,4 101 100,7 102,2 101,1 98,7 64.8 18.6November 01 1,2 39,9 40,1 1,6 1,5 38,5 1,7 38,5 1,7 38,5 39,8 40,4 36,4 1,7 40,2 40 40,5 40,1 39,3 27.2 7.8December 01 20,2 28,8 29,1 29,3 28,1 28,8 27,8 28 29,1 27,9 29 29,6 26,4 29,2 29,5 29,1 29,5 29,3 28,8 20.8 6.0January 02 26,6 40,9 41,5 41,7 40,2 41,1 39,7 39,8 41,3 39,6 41,3 42,1 38,6 41,1 41,8 41,4 41,6 41,7 41 27.8 8.0February 02 53,7 79,1 80,5 80,7 79 80,5 78 77,7 80,5 77,7 80,1 81,3 77,3 62,5 80,9 80,6 81,4 80,9 79,3 51.3 14.8

ECN-C-02-039 25

6. CONCLUDING REMARKS

1. The integrated PV-sunshade façade contributes considerably to the energy efficiency of therenovated building. The electricity generation by the PV modules is rather high: PV willcover approximately 90% of the electricity consumption of the building related electricityuse. Also, the energy saving effect of the sunshade system should not be underestimated.Application of such a system will reduce the heat load of the building considerably, thusavoiding the need for an energy swallowing cooling system.

2. Computer simulation programs such as TRNSYS, ADELINE and REDUCE confirm that aconsiderable improvement of the interior climate and comfort can be achieved by using theintegrated PV/sunshade façade and roof to avoid external heat load, by using night coolingwith fresh air and by reducing the internal heat generation by efficient use of daylightillumination.

3. However, certain matters like the exact effect of the lamellas on the daylight in the rooms,and the staff’s perception of the new situation cannot so easily be predicted by simulationprograms. Also, effects from colour, dazzle, perforation of the lamellas and consequencesfor the layout of the rooms (where to place computers, desks, tables etc.) require the use of amock-up.

4. A large scale project as this PV integrated shading system should never be made beforetesting the visual, physical and constructional implications with the help of a mock up.

5. As the design process advanced, there were increasingly urgent questions to be solved.Because the project largely involved the development of a new product, many of thesequestions were production related. Can the lamellas be folded at a width of 3.3 meter? Whatabout ventilation openings? Adequate ventilation is needed to cool the PV panels and alsoto prevent condensation. Experiments have shown that minimum ventilation openings of 2 x50 cm2 per module (0.5 m2) are required. These openings have been made at several placesin the lamella, and seem to be adequate. Further experiments with a mock-up could provewhich places for ventilation openings might give the best results.

6. Questions had to be solved involving wiring. The modules must be correctly coupled(parallel and serial) with a minimum loss in the wires. In addition, the wiring should bemounted soundly, accessible and invisible to the extent possible. The wiring of the movablelamella must be made so that deterioration by frequent motion is impossible. Practice mustshow whether the performance of the construction is satisfactory.

7. The deterioration of the hinges and the drive mechanism of the movable lamellas have beenestablished using the mock-up. The Danish manufacturer of the lamellas, Dasolas, hasconsiderable experience with moveable sunshade devices, though not so much with thelarge size as is required for this project. Experience with the mock-up has led to designchanges.

8. Because the building where the integrated PV/sunshade system has been applied is situatedin a windy area only 200 meters from the North Sea, the influence of wind (noise), salt andsand was examined with a mock-up. The awning construction was not examined in themock up, as the mock-up concerned the ground floor and the first floor, and as the design ofthe awning changed during the process. It resulted in damage and construction improvementafter the first storm.

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9. The above demonstration project certainly served the purpose of IEA Task 7 case studieswhere experts were able to discuss questions regarding design, production, wiring,interconnection of PV and lamellas, and also non-technical aspects such as the involvementand role of the local government, the utility and the owner/user. The project has receivedmuch attention, both on a national and international level. It will undoubtedly encourage theapplication of PV systems as an energy-conscious retrofit.

Zonne-energiesysteem Gebouw 31

Momentane situatie:

Opbrengstwaarden:

Periode Instralingsenergie-dichtheid (kWh/m2)

Horiz. vlak Array-vlakGisteren

Vorige weekVorige maand

Vanaf 1/6/2001(*) Genormeerd

Figure 13 Visualisation of the envisaged public web-pa

xxxW/m2

ZonnepanelenHorizontaal vlak

xxxW/m2

xxx

Elektrische energie(kWh)

DC AC

naar een Standaard jaar

ge (in Dutch)

DC/AC-omvormer

W

xxx

ECN-C-02-039

Specifiekeopbrengst(*)kWh/kWp

voor Nederland

W

elektriciteitsnet