The heating energy requirement of buildings can be reduced from today’s high levels to almost zero if buildings are thoroughly insulated, passive solar gains through windows are used efficiently, and the supply of fresh air takes place via a heat-recovery system. However, all buildings still have an energy requirement for electricity and warm water provision which cannot be met by passive measures. Active solar technologies are especially appropriate for meeting this energy requirement, as the elements can be integrated into the shell of the building, thus substituting classical building materials and requiring no additional area. Solar modules for photovoltaic electricity production can be built like glazing into all common construction systems, and are characterised by a simple, modular system technology. Thermal collectors with water and air as heat conveyors are installed for warm water provision and heating support, and can replace complete roof covers if the collector surface is large. For today’s increasing air-conditioning and cooling demand, especially in office buildings, thermally driven low-temperature techniques are interesting; these can use not only solar energy but also waste heat. Apart from electricity production, solar heating and cooling, solar energy is used in the form of daylight and thus contributes to a reduction in the growing electricity consumption. The intention of this book is to deal with all solar technologies relevant to meeting the energy requirements of buildings, so that both the physical background is understood and also concrete approaches to planning are discussed. The basic precondition for the sizing of active solar plants is a reliable database for hourly recorded irradiance values. New statistical procedures enable the synthesis of hourly radiation data from monthly average values, which are available world-wide from satellite data, and also partly from ground measurements. For the use of solar technologies in urban areas, an analysis of the mutual shading of buildings is particularly relevant.
Solar thermal systems with air – and water-based collectors are a widely used technology. For the engineer-planner, the system-oriented aspects such as interconnecting, hydraulics and safety are important, but for the scientific simulation of a thermal system the heat transfer processes must also be examined in detail. The fact that with thermal collectors not only heat can be produced, is pointed out in the extensive section on solar cooling. The current technologies of adsorption and absorption cooling as well as open sorption-supported air conditioning can all be coupled with thermal collectors and offer a large energy-saving potential, particularly in office buildings.
Photovoltaic generation of electricity is then discussed, with the necessary basics for current-voltage characteristics as well as the system-oriented aspects. Since photovoltaics offers particularly interesting building integration solutions, new procedures for the calculation of thermal behaviour must be developed. For these new elements, component characteristic values are derived, which are needed for the building’s heating-requirement calculations.
The book concludes with a discussion of passive solar energy use, which plays an important role in covering heat requirements and in the use of daylight. What is crucial for the efficiency of solar energy is the effective storage capability of the components, which must also be known in cases where transparent thermal insulation is used. Linking an outline of basic physical principles with their applications is designed to facilitate a sound knowledge of innovative solar-building technologies, and to contribute to their being accepted in planning practice.
This book is due to the initiative of my now retired colleague Professor Jenisch, who was always interested in solar technology, while working on classical thermal building physics. His contacts with the German publishing house Teubner led first to a German version of the current book, which appeared in 2001.
Within the Department of Building Physics at the Stuttgart University of Applied Sciences, solar technology is now very important. Without the support of the research group on solar energy, the broad subject range of the book would not have been possible. I would like to thank my co-workers Christa Arnold, Uwe Bauer, Volker Fux, Martin Huber, Guenther Maendle, Uli Jakob, Dieter Schneider, Uwe Schuerger and Peter Seeberger for their input and support with many of the book’s graphics. I also wish to thank my theory colleague, Professor Kupke, for his various suggestions regarding the section on passive solar energy use.
I am, however, most indebted to Dr Juergen Schumacher for his continuous support, which extends beyond the book’s content. It was with his simulation environment INSEL, at an intensive conference in Barcelona, that most of the calculation results were obtained.
Ursula Eicker, Stuttgart January 2003