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PV in buildings - the influence of pv on the design and planning process of a building
WREC 1996
PV IN BUILDINGS - THE INFLUENCE OF PV ON THE DESIGN AND PLANNING PROCESS OF A BUILDING I. HAGEMANN
Planungsbiiro HAGEMANN Annuntiatenbach 43, D-52062 Aachen, Germany, Fax/Phone: +49/241/30547
ABSTRACT The incorporation of photovoltaic modules in the structure of a building is becoming popular. Advances in PV-technology allow today to use PV-modules in addition to an electricity production for several other purposes on a building, like for example as a roof-light, a wall-cladding or a window-pane. To achieve the goal, that a PV-System is becoming on all levels of construction and design an integral part of an overall concept of a building a close collaboration among all the people, being involved in the design process of a building, is necessary. Such a collaboration is still missing. Therefor this paper describes the reasons for this present situation and gives a perspective of changes in the design and building process, which are necessary to be able to realise successfully Building Integrated-PV-Systems.
KEYWORDS Photovoltaic; Building-Integrated-Photovoltaic (BIPV); Architecture; Architectural Design Process;
INTRODUCTION In recent years, society has become aware and therefore sensitive to the destruction of the natural environment with its unforeseeable economic and ecological consequences. With the purpose of conservation, goals have now been set to reduce the consumption of fossil fuels and to utilise energy more efficiently and cost-effectively. As a result of these goals, specifications and requirements for the construction and design of buildings have also changed. In the centre of interest is the building envelope, the interface between the outside and inside worlds. Owing to the growing expectations of today and tomorrow, the building interface has become a complex, multifunctional component. New technological developments have allowed completely different visions of a conventional facade or roof to be created. Apart from providing protection against the weather and acting as a defence mechanism against intruders, the envelope must increasingly meet society' s growing insistence on comfort, the obligation to save fossil energy, the need to avoid the unwholesome effects of a man-made environment such as noise pollution, waste gas emissions or other influences and the demand to make use of active and passive solar design principles and techniques. One of the new requirements which has only arisen most recently with respect to the multi-functionalism of 467
WREC 1996 a building exterior is the incorporation of photovoltaic modules in the structure of a building with the aim to convert solar energy into electric power. This technology can be used in different ways in both existing and new buildings. Apart from generating electricity, photovoltaic modules can be used today for different purposes on a building, like for example as a shading system, window pane, semitransparent glass facade, building exterior panelling, skylight, exterior panelling, parapet unit or roofing material or roofing system.
PRESENT SITUATION OF BIPV-SYSTEMS The evolution of photovoltaic systems has been dominated by electrical engineering concepts. Only most recently the research and development of the prerequisites for successful photovoltaic applications in buildings in relation to architectural planning and design has begun. An analysis of buildings in which photovoltaic systems have been used has shown that the simultaneous integration of design, technological and energy aspects has been successful in only a very few cases. The reasons for the majority of failures can be traced back to various sources: • Construction personnel and architects lack information about PV • The architects does not have the appropriate planning tools to make competent decisions • The complexity and interdependence of the demands set on the building are inconceivable for one single person • The overall concept is not taken into account; isolated view of individual aspects • Communication problems arise among those involved in the building process • Co-operation among those involved in the building process is lacking and thus the view and purpose of the total concept are lost • Due to the lack of knowledge, understanding and interest, the parties involved do not take the time or trouble to examine the work and the targets set by the others involved in the building and planning process
CHARACTERISTICS OF ARCHITECTURAL PLANNING AND DESIGN The architectural design of a building not only focuses on meeting functional, rational and cost-effective needs. Architecture also has to do with the conscious effort to direct a play of the senses of perception with the view to create an experience of the shape and structure of an overall space. This can be achieved, for example, by the creation of a relationship and thus a comparison between views of indoor and outdoor spaces, by the play of light and shadows and by the aesthetic design of shapes and surfaces. The more senses which are addressed and the more multi-layered the information to be obtained is, the more intriguing a space experienced appears to us. The term, "space", is to be understood in this case as indoor enclosures and outdoor spaces as well as the courtyard enclosures and street open-air spaces. Architectural design is based on the assumption of an experience of overall space, but is made up of more than the sum of its individual parts. If the experience of space is broken down into parts, the significance of the individual parts within the whole is lost. This means that the completed puzzle arrangement of the individual parts alone does not create an experience of space. More important are the correlation and interrelationships among the individual elements and their multi-layered correlation to one another and their contribution to the coherence of the whole. This exposition on the characteristics of architectural planning and design will provide an initial impression on the importance of taking the design concept into account with regard to the mounting of the photovoltaie modules on buildings. Only in this way can the photovoltaic modules act as an essential part of the overall experience of space and design. Photo 1 and 2 show two examples of buildings with aesthetically and successfully design-integrated photovoltalc systems. 468
WREC 1996
Photo 1: Wall cladding with PV; Church Steckborn, Switzerland
Photo 2: PV-S, .hading system, South face of the Education Centre of the Hamburg Electricity Works, Germany
PV-SYSTEMS IN THE CONTEXT OF AN ENERGY - CONSCIOUS DESIGN Using photovoltaic systems is only one option in the field of harvesting active and passive solar energy in buildings. Solar energy use must always been seen in the context of building procedures because techniques can be used to complement one another or can be used next to one another while other techniques, in turn, exclude each other as different requirements for their realisation must be met, or they would have a negative effect on each other. Here are two examples: Photo 2 show a building where creepers, which have big green leaves in summers, use the vertical steel structure at the south face of the building as a climbing post. The benefit of these leaves is that they act as a kind of "passive" cooling system. The leaves evaporate water and in summer shelter the south-facing exterior from direct sunlight which reduces the heat load in the rooms as building exterior does not heat up and gives glare-free light. On the other hand, the big leaves are also a drawback as they cast shadows or partial shadows on some of the photovoltalc modules. This results in losses in the electricity production of some or even most of the installed photovoltaic modules at a time where an optimal electric power generation would be possible. Consequently, the use of greenery on the face of the building in this form is not consistent with the simultaneous use of photovoltaic elements on the building exterior. To avoid such design defects it is necessary to know and to take into account the requirements and limits of the different active and passive solar energy techniques for buildings and to take these into account in the general concept. An overall energy scheme must be developed for the building right at the beginning of the construction project because the energy requirements for a building are initially determined and affected decisively in the drawing board stage by the layout of the building shape, orientation and use. The chances of having any influence on the future energy requirements decrease with every further step of the planning and building process and the effort to make any changes to these requirements increases accordingly (see Fig. 1). In principle, the architect must have considerable knowledge of the various options with regard to active and passive solar energy applications and must be in possession of the proper information to make decisions so that he is in a position to select quickly and with little effort the most suitable solar energy techniques according to cost-effectiveness. This decision procedure is already difficult for the architect in small projects and in larger projects cannot be 469
WREC 1996 managed alone. These projects are so complex that an individual cannot keep all the details in mind in order to make rational decisions concerning the energy requirements. When the requirements are not sufficiently clear, the architect customarily uses his intuition in order to find a solution. In the planning of energy requirements for a building, this method only leads to unsatisfactory results as any energy-related decisions for building can only be based on scientific knowledge, insights and rational decisions. This is why it is necessary to expand the drawing board procedure to include a scheme for energy requirements and to allow for rational decisions. The architect can no longer produce the initial design of a new building and then include the experts involved in the construction process in the subsequent planning stage. In future, all those involved in the building and designing process must work together at the beginning of a new project to create a new building (see Fig. 2).
Phases of the Development of a Building
High
i
! Lay Down of the Energy Consumption of a Building
Design and Calculmtion of the Energy Consumpiton of a Building Respohsiblli~ in the Past:
Responsibility in the Future:
LOW m Beginning
Fig. 1:
Building Process
End
Determination of the future energy requirements of a building
Fig. 2:
¢,
Architect Engineer (For Energy, Statics, Building Technology, etc
Engineer (For Bne~ly, StaBc~,
Planning responsibilities and lay down of energy consumption
CONDITIONS FOR A SUCCESSFUL COLLABORATION ON BIPV-SYSTEMS It must be made clear that the integration of photovoltaic systems in the drawing board drafts, design and building construction is always the result of a mutual effort of all experts. None of the experts involved is in the position to find the best possible solution on his own. Successful architecture is the result of optimum interdisciplinary teamwork. In order to achieve this end, certain conditions must be met and observed: • Teamwork among experts only brings fruit to bear when everyone shares the same attitudes, values and objectives, for instance, with respect to the quality of design, dedication to work etc. • Each expert must take time to listen to the others • Direct communication is required • Confidence in all involved is essential • Prejudices, including the own ones, need to be questioned • All planning preconceptions or ideas must be given up in favour of a mutually worked out approach • Each contribution should not be seen as an end in itself, but as a contribution to the common aim to create the best possible solution.
REFERENCES Photo 1 and 2; Fig. 1 and 2: Ingo Hagemann, Germany 470
PV IN BUILDINGS - THE INFLUENCE OF PV ON THE DESIGN AND PLANNING PROCESS OF A BUILDING I. HAGEMANN
Planungsbiiro HAGEMANN Annuntiatenbach 43, D-52062 Aachen, Germany, Fax/Phone: +49/241/30547
ABSTRACT The incorporation of photovoltaic modules in the structure of a building is becoming popular. Advances in PV-technology allow today to use PV-modules in addition to an electricity production for several other purposes on a building, like for example as a roof-light, a wall-cladding or a window-pane. To achieve the goal, that a PV-System is becoming on all levels of construction and design an integral part of an overall concept of a building a close collaboration among all the people, being involved in the design process of a building, is necessary. Such a collaboration is still missing. Therefor this paper describes the reasons for this present situation and gives a perspective of changes in the design and building process, which are necessary to be able to realise successfully Building Integrated-PV-Systems.
KEYWORDS Photovoltaic; Building-Integrated-Photovoltaic (BIPV); Architecture; Architectural Design Process;
INTRODUCTION In recent years, society has become aware and therefore sensitive to the destruction of the natural environment with its unforeseeable economic and ecological consequences. With the purpose of conservation, goals have now been set to reduce the consumption of fossil fuels and to utilise energy more efficiently and cost-effectively. As a result of these goals, specifications and requirements for the construction and design of buildings have also changed. In the centre of interest is the building envelope, the interface between the outside and inside worlds. Owing to the growing expectations of today and tomorrow, the building interface has become a complex, multifunctional component. New technological developments have allowed completely different visions of a conventional facade or roof to be created. Apart from providing protection against the weather and acting as a defence mechanism against intruders, the envelope must increasingly meet society' s growing insistence on comfort, the obligation to save fossil energy, the need to avoid the unwholesome effects of a man-made environment such as noise pollution, waste gas emissions or other influences and the demand to make use of active and passive solar design principles and techniques. One of the new requirements which has only arisen most recently with respect to the multi-functionalism of 467
WREC 1996 a building exterior is the incorporation of photovoltaic modules in the structure of a building with the aim to convert solar energy into electric power. This technology can be used in different ways in both existing and new buildings. Apart from generating electricity, photovoltaic modules can be used today for different purposes on a building, like for example as a shading system, window pane, semitransparent glass facade, building exterior panelling, skylight, exterior panelling, parapet unit or roofing material or roofing system.
PRESENT SITUATION OF BIPV-SYSTEMS The evolution of photovoltaic systems has been dominated by electrical engineering concepts. Only most recently the research and development of the prerequisites for successful photovoltaic applications in buildings in relation to architectural planning and design has begun. An analysis of buildings in which photovoltaic systems have been used has shown that the simultaneous integration of design, technological and energy aspects has been successful in only a very few cases. The reasons for the majority of failures can be traced back to various sources: • Construction personnel and architects lack information about PV • The architects does not have the appropriate planning tools to make competent decisions • The complexity and interdependence of the demands set on the building are inconceivable for one single person • The overall concept is not taken into account; isolated view of individual aspects • Communication problems arise among those involved in the building process • Co-operation among those involved in the building process is lacking and thus the view and purpose of the total concept are lost • Due to the lack of knowledge, understanding and interest, the parties involved do not take the time or trouble to examine the work and the targets set by the others involved in the building and planning process
CHARACTERISTICS OF ARCHITECTURAL PLANNING AND DESIGN The architectural design of a building not only focuses on meeting functional, rational and cost-effective needs. Architecture also has to do with the conscious effort to direct a play of the senses of perception with the view to create an experience of the shape and structure of an overall space. This can be achieved, for example, by the creation of a relationship and thus a comparison between views of indoor and outdoor spaces, by the play of light and shadows and by the aesthetic design of shapes and surfaces. The more senses which are addressed and the more multi-layered the information to be obtained is, the more intriguing a space experienced appears to us. The term, "space", is to be understood in this case as indoor enclosures and outdoor spaces as well as the courtyard enclosures and street open-air spaces. Architectural design is based on the assumption of an experience of overall space, but is made up of more than the sum of its individual parts. If the experience of space is broken down into parts, the significance of the individual parts within the whole is lost. This means that the completed puzzle arrangement of the individual parts alone does not create an experience of space. More important are the correlation and interrelationships among the individual elements and their multi-layered correlation to one another and their contribution to the coherence of the whole. This exposition on the characteristics of architectural planning and design will provide an initial impression on the importance of taking the design concept into account with regard to the mounting of the photovoltaie modules on buildings. Only in this way can the photovoltaic modules act as an essential part of the overall experience of space and design. Photo 1 and 2 show two examples of buildings with aesthetically and successfully design-integrated photovoltalc systems. 468
WREC 1996
Photo 1: Wall cladding with PV; Church Steckborn, Switzerland
Photo 2: PV-S, .hading system, South face of the Education Centre of the Hamburg Electricity Works, Germany
PV-SYSTEMS IN THE CONTEXT OF AN ENERGY - CONSCIOUS DESIGN Using photovoltaic systems is only one option in the field of harvesting active and passive solar energy in buildings. Solar energy use must always been seen in the context of building procedures because techniques can be used to complement one another or can be used next to one another while other techniques, in turn, exclude each other as different requirements for their realisation must be met, or they would have a negative effect on each other. Here are two examples: Photo 2 show a building where creepers, which have big green leaves in summers, use the vertical steel structure at the south face of the building as a climbing post. The benefit of these leaves is that they act as a kind of "passive" cooling system. The leaves evaporate water and in summer shelter the south-facing exterior from direct sunlight which reduces the heat load in the rooms as building exterior does not heat up and gives glare-free light. On the other hand, the big leaves are also a drawback as they cast shadows or partial shadows on some of the photovoltalc modules. This results in losses in the electricity production of some or even most of the installed photovoltaic modules at a time where an optimal electric power generation would be possible. Consequently, the use of greenery on the face of the building in this form is not consistent with the simultaneous use of photovoltaic elements on the building exterior. To avoid such design defects it is necessary to know and to take into account the requirements and limits of the different active and passive solar energy techniques for buildings and to take these into account in the general concept. An overall energy scheme must be developed for the building right at the beginning of the construction project because the energy requirements for a building are initially determined and affected decisively in the drawing board stage by the layout of the building shape, orientation and use. The chances of having any influence on the future energy requirements decrease with every further step of the planning and building process and the effort to make any changes to these requirements increases accordingly (see Fig. 1). In principle, the architect must have considerable knowledge of the various options with regard to active and passive solar energy applications and must be in possession of the proper information to make decisions so that he is in a position to select quickly and with little effort the most suitable solar energy techniques according to cost-effectiveness. This decision procedure is already difficult for the architect in small projects and in larger projects cannot be 469
WREC 1996 managed alone. These projects are so complex that an individual cannot keep all the details in mind in order to make rational decisions concerning the energy requirements. When the requirements are not sufficiently clear, the architect customarily uses his intuition in order to find a solution. In the planning of energy requirements for a building, this method only leads to unsatisfactory results as any energy-related decisions for building can only be based on scientific knowledge, insights and rational decisions. This is why it is necessary to expand the drawing board procedure to include a scheme for energy requirements and to allow for rational decisions. The architect can no longer produce the initial design of a new building and then include the experts involved in the construction process in the subsequent planning stage. In future, all those involved in the building and designing process must work together at the beginning of a new project to create a new building (see Fig. 2).
Phases of the Development of a Building
High
i
! Lay Down of the Energy Consumption of a Building
Design and Calculmtion of the Energy Consumpiton of a Building Respohsiblli~ in the Past:
Responsibility in the Future:
LOW m Beginning
Fig. 1:
Building Process
End
Determination of the future energy requirements of a building
Fig. 2:
¢,
Architect Engineer (For Energy, Statics, Building Technology, etc
Engineer (For Bne~ly, StaBc~,
Planning responsibilities and lay down of energy consumption
CONDITIONS FOR A SUCCESSFUL COLLABORATION ON BIPV-SYSTEMS It must be made clear that the integration of photovoltaic systems in the drawing board drafts, design and building construction is always the result of a mutual effort of all experts. None of the experts involved is in the position to find the best possible solution on his own. Successful architecture is the result of optimum interdisciplinary teamwork. In order to achieve this end, certain conditions must be met and observed: • Teamwork among experts only brings fruit to bear when everyone shares the same attitudes, values and objectives, for instance, with respect to the quality of design, dedication to work etc. • Each expert must take time to listen to the others • Direct communication is required • Confidence in all involved is essential • Prejudices, including the own ones, need to be questioned • All planning preconceptions or ideas must be given up in favour of a mutually worked out approach • Each contribution should not be seen as an end in itself, but as a contribution to the common aim to create the best possible solution.
REFERENCES Photo 1 and 2; Fig. 1 and 2: Ingo Hagemann, Germany 470