Living with the Sun: Modern Technology in Solar Architecture

Living with the Sun: Modern Technology in Solar Architecture Helmut Tributsch Modern solar architecture has been greatly enriched by the scientific under­ standing of the natural laws of heat and light radiation as well as by drawing on information from traditional architec­ ture. Completing this has been the in­ creasing selection of newly developed materials—from cheap and efficient insulating materials and latent heatstorage materials to electronic semicon­ ductors that transform sunlight into electricity. Solar electricity has versatile applications and can play a decisive role in improving the quality of life and the comfort level in solar houses. The collection of the sun's heat through glass can be improved by using a radiation-selective coating or, in cases where light is not to be used for other Helmut Tributsch (researcher, scientist), Hahn-MeitnerInstitut Berlin GmbH, Glienicker Strasse 100, D-14109 Berlin, Germany. Received 17January 1995. Manuscript solicited by Jürgen Claus. This paper is an abbreviated version of Helmut Tributsch, "Living with the Sun," in H. Scheer, M. Ghandi, D. Aitken, Y. Hamakawa, W. Palz, eds., The Yearbook ofRenewable Energies (Bochum, Germany: Ponte Press, 1992) pp. 72-73. © 1992 Hermann Scheer. Reprinted by permis­ sion. purposes, through transparent heat in­ sulation. Sunlight can find its way to the blackened wall of a building through in­ sulating synthetic material with a capil­ lary structure or through layers of aero gels. The loss of the generated warmth to the outside can be effectively hin­ dered through the air-filled hollow spaces in the insulation layers. Walls and floors can have the capacity to effec­ tively store energy by using a construc­ tion in which they are filled with a material that, when heated, changes in constitution from solid to liquid. A lightcollecting structure on the roof, for ex­ ample a collector that does not need to follow the sun, absorbs its rays and trans­ fers them through carriers into the in­ side rooms, thus providing light. It is relatively simple to build small solar houses because of their favorable sur­ face/volume relationship and the fact that they receive relatively large amounts of sunlight. Research has not yet focused on solar buildings and energy-conserving struc­ tures in urban areas. In such densely populated areas, such buildings will be able to provide only a limited amount of the energy required. In addition, it will be imperative that a new aesthetic for urban solar structures be devel­ oped. The solar cells and other energytransferring elements, including transparent insulation structures and coated glass, must be an aesthetically integrated part of the facade—pleasing to the eye, useful and effective. The ef­ fort must be made to establish an aes­ thetic form for solar structures in which their active and passive systems fulfill their structural and energy-saving pur­ poses, while at the same time creating a cohesive, expressive artistic impression. As architectural emphasis shifts from massive to lighter building design, focus on the function of the exterior in­ creases. Lacking all storage capacity, the "outer shell" is responsible for maintain­ ing an interior temperature equilib­ rium. This trend will be a major element in solar architecture, considering the design advantages that such "intelligent exteriors" offer architects (Fig. 3). The function of solar buildings will be increasingly similar to that of living or­ ganisms whose outer skin systematically regulates and controls inner require­ ments. Modern solar houses could also be outfitted with movable walls and floors, foldable and mobile room divid­ ers, or they could be oriented toward the sun. These "skins" would alternate between functioning as light absorbers and light reflectors and, depending on specific conditions, could use air pock­ ets as insulators or be bridged by con­ ductors. Further, die flexible treatment of sunlight by concentrators, reflectors, diaphragms, lenses or tinted and photochromic or electrochromic glass would be possible through the use of multilayered , functional walls. Computers responsible for regulat­ ing this outer skin will be equipped with software capable of calculating and optimizing the energy transfer as well as meeting the demands of the inhabit­ ants. Thus, computers will minimize problems for the solar energy balance. These perspectives emphasize the im­ portance of specialized fields such as computer science and control...