PV-INTEGRATION IN SOLAR SHADING (RENOVATION) AND PV-INTEGRATION IN ATRIUM GLAZING (NEW BUILDING), ECN 31 AND 42 - PETTEN (NL) ir. Tjerk Reijenga BEAR Architecten P.O. Box 349, NL-2800 AH Gouda, The Netherlands tel.: +31 182 529899, fax: +31 182 582599, e-mail: [email protected], internet: www.bear.nl The renovation of laboratory building 31 and the new office- and laboratory building 42 of the Netherlands Energy Research Foundation ECN in Petten are a good examples of the building integration of photovoltaic energy. Besides, the buildings demonstrate and increase the know-how and experience of the company on the sustainable use of energy in the built environment. The laboratory (building 31) was built in 1963 and is (during the renovation) equipped with a PV integrated sun shading system for the south facade and a PV roof. The capacity of the system is about 72 kWp. The building lay-out of the new building 42 is designed to lower the energy use by maximising solar gain and the use of daylight. The glass-covered corridor on the first floor, with its entrances to the laboratory and office- modules, is the connecting element between the existing laboratory building 31 and the new building 42. The use of photo voltaic laminates in the curved glass roof prevents overheating in summer and provides diffuse lighting. The capacity of this PV system is about 43 kWp. More information can be found on the website: www.bear.nl. Keywords: Building integration - 1: Photovoltaic - 2: Shading – 3: Sustainable Figure 1: ECN buildings 42 (left) and 31 (right). 1. INTRODUCTION 1.1 Aim of the project The aim of the project is to construct energy- efficient and sustainable buildings and demonstrate the use of renewables in the built environment. Both, the retrofit of building 31 and the new office- and laboratory building 42 of the Netherlands Energy Research Foundation ECN in Petten are a demonstration of these aims. The projects are supported by EU Thermie, NOVEM and the utility NUON. In order to make PV more economical, PV integration in buildings is an option that may save money on supporting systems, savings in roofing materials, and savings in floor space.
PV-INTEGRATION IN SOLAR SHADING (RENOVATION) AND PV-INTEGRATION IN ATRIUM GLAZING (NEW BUILDING), ECN 31 AND 42 - PETTEN (NL)
Mar 29, 2023
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Microsoft Word - vb2.7paper.docir. Tjerk Reijenga BEAR Architecten
P.O. Box 349, NL-2800 AH Gouda, The Netherlands tel.: +31 182 529899, fax: +31 182 582599, e-mail: [email protected], internet: www.bear.nl
The renovation of laboratory building 31 and the new office- and laboratory building 42 of the Netherlands Energy Research Foundation ECN in Petten are a good examples of the building integration of photovoltaic energy. Besides, the buildings demonstrate and increase the know-how and experience of the company on the sustainable use of energy in the built environment. The laboratory (building 31) was built in 1963 and is (during the renovation) equipped with a PV integrated sun shading system for the south facade and a PV roof. The capacity of the system is about 72 kWp. The building lay-out of the new building 42 is designed to lower the energy use by maximising solar gain and the use of daylight. The glass-covered corridor on the first floor, with its entrances to the laboratory and office- modules, is the connecting element between the existing laboratory building 31 and the new building 42. The use of photo voltaic laminates in the curved glass roof prevents overheating in summer and provides diffuse lighting. The capacity of this PV system is about 43 kWp. More information can be found on the website: www.bear.nl. Keywords: Building integration - 1: Photovoltaic - 2: Shading – 3: Sustainable
Figure 1: ECN buildings 42 (left) and 31 (right).
1. INTRODUCTION
1.1 Aim of the project The aim of the project is to construct energy-
efficient and sustainable buildings and demonstrate the use of renewables in the built environment. Both, the retrofit of building 31 and the new office- and laboratory building 42 of the Netherlands Energy Research Foundation ECN in Petten are a demonstration of these aims.
The projects are supported by EU Thermie, NOVEM and the utility NUON.
In order to make PV more economical, PV integration in buildings is an option that may save money on supporting systems, savings in roofing materials, and savings in floor space.
2. APPROACH
2.1 ECN Petten The buildings are located at the site of he
Netherlands Energy Research Foundation ECN in Petten, the Netherlands. ECN is attractively situated in the dunes in the Northern part of Holland, close to the village of Petten.
2.2 Building 31 In 1997 the ECN unit for ‘Renewable Energy in the
Built Environment’ made a study to evaluate the building condition of laboratory building 31 as well as facts of energy consumption. The survey showed that the existing building (constructed in 1963) has several major technical and thermal shortcomings, which will be taken care of in the renovation process.
Building 31 had several technical and thermal problems:
• bad insulation of the envelope and thermal bridges; • overheating in mid summer; inefficient lighting
system; • high rate ventilation system for the laboratories
with low efficiency and comfort; • high heating and electricity demand; • facade in bad condition led to draught due to
thermal bridges; • draught, due to ventilation system and badly
distributed heat. Table 1: Problems of laboratory 31.
For the laboratory 31 a PV-integrated shading system have been designed. The project is a co- operation between ECN, BEAR Architecten, utility NUON, Shell Solar Energy and the Italian architect Cinzia Abbate (Rome). The Danish manufacturer Dasolas/Alco is involved in producing the combined PV support / sun shading system.
Figure 2: Integration of PV in solar shading (building 31)
To prevent overheating during summertime, the south façade has been provided with sunshades. PV modules have been integrated in this shading system. To optimise solar gain there needs to be a certain distance between the lamellas of the system. For fine tuning the shading system, a simple second system i s placed on the inside. Furthermore, the shading system diffuses the daylight and the structure allows easy
access to the façade for building maintenance and window cleaning.
A PV roofing system has been designed and installed in co-operation with BP Solar. The installed capacity of the system is approx. 35 kWp.
When the building renovation is completed, the primary energy demand will be reduced with 75%. The amount of PV that will be applied is about 72 kWp : 50% integrated in the façade and 50% at the roof. All together the PV system will produce about 56,440 kWh per year.
The renovation project is part of the EC Thermie program (SE 0115/97/NL/DK) and financially supported by the EC. The project is constructed in the years 2000- 2001.
2.3 Building 42 The office building 42 consists of three building
units. The construction of the first unit is finished in March 2001. The other unit’s wil be built in the next years.
Figure 3: The corridor between the buildings.
The building has been designed to maximise the use of daylight and to minimise the use of artificial light. To accomplish this the structure of the building i s compact and the building has several atriums allowing a maximum use of daylight. All working places are situated in the daylight zone near the facade. The glass- covered corridor on the first floor, with its entrances to the office-units, will be the connecting element between the building. The use of photovoltaic cells in the curved glass roof and a lot of natural ventilation prevent overheating in the summer. The 43 kWp PV system i s installed by BP Solar.
Realized options for building 42: • compact building form; • high insulation values for floor, roof, windows and
facades; • unheated corridor (conservatory) space as a climatic
buffer; • reduction of cooling load by the ventilated corridor
with PV glazing (parasol idea); • daylight controlled artificial lighting system; • ventilation concept with heat recovery system; • natural summer night ventilation by automatic
opening windows; • optimized daylight through the corridor and atrium; • air-heating system to cover the low demand.
Table 2: Options realized in building 42
3. THE PV SYSTEM
3.1 Building 31, the façade The building had a problem of overheating in
summer. An outer sunshading system was necessary. It was clear that the PV modules should be integrated in the sunshading system. Such a solution may: • give good shading of the building in summer; • optimize solar gain; • diffuses daylight; • give easy access for maintenance of the building and
cleaning of the windows (maintenance walkway). Besides there is more than one reason that justifies
the use of integrated PV modules in the shading device: construction costs will be optimized by the elimination of costs of a conventional PV module support system; interior light and temperature will be improved and energy is produced directly where needed.
The choice should be made whether the shading device should be mounted close to the facade or at a certain distance. Furthermore, the size of the lamellas had to be discussed: should a few, wide lamellas be chosen or a larger number of slim ones? What should be the length of the lamellas?
From the point of view of maintenance, accessibility and window cleaning it was decided to have the shading/PV device constructed as a separate facade, about 80 cm from the building, connected to the main structure of the building. The length of the lamellas followed from the building structure grid.
In order to make a choice for the width of the lamellas various solutions for an integrated system were examined: • two large lamellas with modules, at a vertical
distance of 1.5 m in a fixed position; • idem with moveable tracking system; • seven small lamellas with modules, at a vertical
distance of 0.5 m in a fixed position; • idem with moveable tracking system.
The study was carried out with a model of a laboratory room scale 1:10 in a daylight chamber and on a solar table. It focused on the solar gain, the heat load of the building, shading of the building, shading of the modules, outside view from the interior and daylight conditions. This study showed, that the best results for solar gain, shading and daylight were obtained with a model using 4 fixed lamellas per floor. Considering the solar ratio between a fixed vertical system and a moveable vertical system, the solar gain i s only approximately 10% higher with a moveable one.
Considering the high costs of a moveable system compared to a fixed structure, and the small difference of solar gain it was decided to select a system that i s fixed in the optimal position (in the Netherlands 37° with the horizon). However, the occupant of the rooms behind can move one lamella, at eye level, in a horizontal position, in order to have a good outside view. After a defined space of time, for instance 20 minutes or so, the lamella will automatically take its position of 37° again. Thus, a continuously varying architectural view is created.
Each lamella will be about 840 mm wide, 3000 mm long and will be covered by three standard multi- crystalline PV modules on the front part. Because of the dimensions of the lamellas the building is shaded
during the summer period. The efficiency of the shading system is about 85%. For fine-tuning the glare, especially in winter, a second, very simple interior shading system is provided.
Because of the new exterior PV/shading system overheating of the south facade will be avoided and an expensive, energy consuming, air-conditioning system is not necessary.
As far as can be predicted from the study, the specific position of the lamellas might improve the distribution of the daylight in the rooms compared to the existing situation. The daylight situation through the rooms might be more equal. However, to be sure about the effect of the integrated PV/sunshading system on the delighting of the rooms behind, a separate study is carried out. This study, consists of advanced daylight computer simulations. After evaluation of the results a mock-up has been built, followed by measurements. But not only daylight aspects are examined by means of the mock-up. Also constructive implications, deterioration of moveable construction parts, questions of manufacturing, color and acceptance by the users of the building are examined in the prototype stage. By spending time and money for the prototype, mistakes are avoided in the construction phase.
3.2 Building 31, the roofing system The PV roofing system was originally meant as a
kind of a parasol, a passive-cooling device for the roof. The roof construction underneath should provide water tightness. As the design of the interior of the building got more and more shape, it became clear that the space between the parasol and the existing roof should be used for technical installations. So it was decided to construct the parasol as a watertight part of the building.
Figure 4: The roof of building 31
3.3 Building 42 Special emphasis has been given to architectural
and constructional aspects of integrating the PV modules in the building.
The glass-covered corridor on the first floor, with its entrances to the office-modules, is the connecting element between building 31 and building 42. In the roof of this unheated and strongly ventilated conservatory, PV modules are integrated. The transparent modules have a 2 centimeters free space between the cells. Thus providing daylight in the conservatory. In this way the use of photovoltaic in the
curved glass roof prevents overheating in summer and provides diffuse daylight. The glass roof is like a parasol for the building under it.
4. SCIENTIFIC INNOVATION AND RELEVANCE
The scientific innovation and relevance of the project are high. The PV system is architecturally integrated in the buildings. The use of solar energy had an important role in the design process. The project shows how new sustainable concepts enriches the architectural value of buildings.
The interest in the project, both from national and international sides, is large. Thus the project may encourage the application of PV systems. The innovative constructions for PV integration in the roofs and in the facade contributes highly to the reduction of heat load of these buildings. Thus, energy consuming air-condition equipment is avoided.
The project is regarded as innovative because of its contribution to new developments in the sun shading industry, the architectural solution, the integration of PV, shading, passive cooling and daylight, the good outside view by moveable lamellas and the good inside view by diffuse lighting. Integration of PV systems in shading devices or in atriums can result in considerable cost reduction.
5. RESULTS / CONCLUSIONS
P.O. Box 349, NL-2800 AH Gouda, The Netherlands tel.: +31 182 529899, fax: +31 182 582599, e-mail: [email protected], internet: www.bear.nl
The renovation of laboratory building 31 and the new office- and laboratory building 42 of the Netherlands Energy Research Foundation ECN in Petten are a good examples of the building integration of photovoltaic energy. Besides, the buildings demonstrate and increase the know-how and experience of the company on the sustainable use of energy in the built environment. The laboratory (building 31) was built in 1963 and is (during the renovation) equipped with a PV integrated sun shading system for the south facade and a PV roof. The capacity of the system is about 72 kWp. The building lay-out of the new building 42 is designed to lower the energy use by maximising solar gain and the use of daylight. The glass-covered corridor on the first floor, with its entrances to the laboratory and office- modules, is the connecting element between the existing laboratory building 31 and the new building 42. The use of photo voltaic laminates in the curved glass roof prevents overheating in summer and provides diffuse lighting. The capacity of this PV system is about 43 kWp. More information can be found on the website: www.bear.nl. Keywords: Building integration - 1: Photovoltaic - 2: Shading – 3: Sustainable
Figure 1: ECN buildings 42 (left) and 31 (right).
1. INTRODUCTION
1.1 Aim of the project The aim of the project is to construct energy-
efficient and sustainable buildings and demonstrate the use of renewables in the built environment. Both, the retrofit of building 31 and the new office- and laboratory building 42 of the Netherlands Energy Research Foundation ECN in Petten are a demonstration of these aims.
The projects are supported by EU Thermie, NOVEM and the utility NUON.
In order to make PV more economical, PV integration in buildings is an option that may save money on supporting systems, savings in roofing materials, and savings in floor space.
2. APPROACH
2.1 ECN Petten The buildings are located at the site of he
Netherlands Energy Research Foundation ECN in Petten, the Netherlands. ECN is attractively situated in the dunes in the Northern part of Holland, close to the village of Petten.
2.2 Building 31 In 1997 the ECN unit for ‘Renewable Energy in the
Built Environment’ made a study to evaluate the building condition of laboratory building 31 as well as facts of energy consumption. The survey showed that the existing building (constructed in 1963) has several major technical and thermal shortcomings, which will be taken care of in the renovation process.
Building 31 had several technical and thermal problems:
• bad insulation of the envelope and thermal bridges; • overheating in mid summer; inefficient lighting
system; • high rate ventilation system for the laboratories
with low efficiency and comfort; • high heating and electricity demand; • facade in bad condition led to draught due to
thermal bridges; • draught, due to ventilation system and badly
distributed heat. Table 1: Problems of laboratory 31.
For the laboratory 31 a PV-integrated shading system have been designed. The project is a co- operation between ECN, BEAR Architecten, utility NUON, Shell Solar Energy and the Italian architect Cinzia Abbate (Rome). The Danish manufacturer Dasolas/Alco is involved in producing the combined PV support / sun shading system.
Figure 2: Integration of PV in solar shading (building 31)
To prevent overheating during summertime, the south façade has been provided with sunshades. PV modules have been integrated in this shading system. To optimise solar gain there needs to be a certain distance between the lamellas of the system. For fine tuning the shading system, a simple second system i s placed on the inside. Furthermore, the shading system diffuses the daylight and the structure allows easy
access to the façade for building maintenance and window cleaning.
A PV roofing system has been designed and installed in co-operation with BP Solar. The installed capacity of the system is approx. 35 kWp.
When the building renovation is completed, the primary energy demand will be reduced with 75%. The amount of PV that will be applied is about 72 kWp : 50% integrated in the façade and 50% at the roof. All together the PV system will produce about 56,440 kWh per year.
The renovation project is part of the EC Thermie program (SE 0115/97/NL/DK) and financially supported by the EC. The project is constructed in the years 2000- 2001.
2.3 Building 42 The office building 42 consists of three building
units. The construction of the first unit is finished in March 2001. The other unit’s wil be built in the next years.
Figure 3: The corridor between the buildings.
The building has been designed to maximise the use of daylight and to minimise the use of artificial light. To accomplish this the structure of the building i s compact and the building has several atriums allowing a maximum use of daylight. All working places are situated in the daylight zone near the facade. The glass- covered corridor on the first floor, with its entrances to the office-units, will be the connecting element between the building. The use of photovoltaic cells in the curved glass roof and a lot of natural ventilation prevent overheating in the summer. The 43 kWp PV system i s installed by BP Solar.
Realized options for building 42: • compact building form; • high insulation values for floor, roof, windows and
facades; • unheated corridor (conservatory) space as a climatic
buffer; • reduction of cooling load by the ventilated corridor
with PV glazing (parasol idea); • daylight controlled artificial lighting system; • ventilation concept with heat recovery system; • natural summer night ventilation by automatic
opening windows; • optimized daylight through the corridor and atrium; • air-heating system to cover the low demand.
Table 2: Options realized in building 42
3. THE PV SYSTEM
3.1 Building 31, the façade The building had a problem of overheating in
summer. An outer sunshading system was necessary. It was clear that the PV modules should be integrated in the sunshading system. Such a solution may: • give good shading of the building in summer; • optimize solar gain; • diffuses daylight; • give easy access for maintenance of the building and
cleaning of the windows (maintenance walkway). Besides there is more than one reason that justifies
the use of integrated PV modules in the shading device: construction costs will be optimized by the elimination of costs of a conventional PV module support system; interior light and temperature will be improved and energy is produced directly where needed.
The choice should be made whether the shading device should be mounted close to the facade or at a certain distance. Furthermore, the size of the lamellas had to be discussed: should a few, wide lamellas be chosen or a larger number of slim ones? What should be the length of the lamellas?
From the point of view of maintenance, accessibility and window cleaning it was decided to have the shading/PV device constructed as a separate facade, about 80 cm from the building, connected to the main structure of the building. The length of the lamellas followed from the building structure grid.
In order to make a choice for the width of the lamellas various solutions for an integrated system were examined: • two large lamellas with modules, at a vertical
distance of 1.5 m in a fixed position; • idem with moveable tracking system; • seven small lamellas with modules, at a vertical
distance of 0.5 m in a fixed position; • idem with moveable tracking system.
The study was carried out with a model of a laboratory room scale 1:10 in a daylight chamber and on a solar table. It focused on the solar gain, the heat load of the building, shading of the building, shading of the modules, outside view from the interior and daylight conditions. This study showed, that the best results for solar gain, shading and daylight were obtained with a model using 4 fixed lamellas per floor. Considering the solar ratio between a fixed vertical system and a moveable vertical system, the solar gain i s only approximately 10% higher with a moveable one.
Considering the high costs of a moveable system compared to a fixed structure, and the small difference of solar gain it was decided to select a system that i s fixed in the optimal position (in the Netherlands 37° with the horizon). However, the occupant of the rooms behind can move one lamella, at eye level, in a horizontal position, in order to have a good outside view. After a defined space of time, for instance 20 minutes or so, the lamella will automatically take its position of 37° again. Thus, a continuously varying architectural view is created.
Each lamella will be about 840 mm wide, 3000 mm long and will be covered by three standard multi- crystalline PV modules on the front part. Because of the dimensions of the lamellas the building is shaded
during the summer period. The efficiency of the shading system is about 85%. For fine-tuning the glare, especially in winter, a second, very simple interior shading system is provided.
Because of the new exterior PV/shading system overheating of the south facade will be avoided and an expensive, energy consuming, air-conditioning system is not necessary.
As far as can be predicted from the study, the specific position of the lamellas might improve the distribution of the daylight in the rooms compared to the existing situation. The daylight situation through the rooms might be more equal. However, to be sure about the effect of the integrated PV/sunshading system on the delighting of the rooms behind, a separate study is carried out. This study, consists of advanced daylight computer simulations. After evaluation of the results a mock-up has been built, followed by measurements. But not only daylight aspects are examined by means of the mock-up. Also constructive implications, deterioration of moveable construction parts, questions of manufacturing, color and acceptance by the users of the building are examined in the prototype stage. By spending time and money for the prototype, mistakes are avoided in the construction phase.
3.2 Building 31, the roofing system The PV roofing system was originally meant as a
kind of a parasol, a passive-cooling device for the roof. The roof construction underneath should provide water tightness. As the design of the interior of the building got more and more shape, it became clear that the space between the parasol and the existing roof should be used for technical installations. So it was decided to construct the parasol as a watertight part of the building.
Figure 4: The roof of building 31
3.3 Building 42 Special emphasis has been given to architectural
and constructional aspects of integrating the PV modules in the building.
The glass-covered corridor on the first floor, with its entrances to the office-modules, is the connecting element between building 31 and building 42. In the roof of this unheated and strongly ventilated conservatory, PV modules are integrated. The transparent modules have a 2 centimeters free space between the cells. Thus providing daylight in the conservatory. In this way the use of photovoltaic in the
curved glass roof prevents overheating in summer and provides diffuse daylight. The glass roof is like a parasol for the building under it.
4. SCIENTIFIC INNOVATION AND RELEVANCE
The scientific innovation and relevance of the project are high. The PV system is architecturally integrated in the buildings. The use of solar energy had an important role in the design process. The project shows how new sustainable concepts enriches the architectural value of buildings.
The interest in the project, both from national and international sides, is large. Thus the project may encourage the application of PV systems. The innovative constructions for PV integration in the roofs and in the facade contributes highly to the reduction of heat load of these buildings. Thus, energy consuming air-condition equipment is avoided.
The project is regarded as innovative because of its contribution to new developments in the sun shading industry, the architectural solution, the integration of PV, shading, passive cooling and daylight, the good outside view by moveable lamellas and the good inside view by diffuse lighting. Integration of PV systems in shading devices or in atriums can result in considerable cost reduction.
5. RESULTS / CONCLUSIONS
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