Solar Power For Buildings

Preface

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.