ENERGY-EFFICIENT WINDOWS: PRESENT AND FORTHCOMING TECHNOLOGY

ABSTRACT Current research and development offers important opportunities for improved energy efficiency of architectural windows. This chapter covers the design criteria for different climates and reviews means to fulfill these criteria by proper materials selection. We discuss glass properties, the importance of multiple glazing, the many uses of surface coated glass, and possibilities connected with materials interposed between glass panes. Among the coatings, we treat those based on noble metals and on doped oxide semiconductors, both of which have static spectrally selective properties, as well as electrochromics-based and thermochromic coatings which enable a dynamic control of the throughput of radiant energy. The fascinating possibilities with electrochromic “smart windows” are pointed out. Angular-selective coatings are discussed briefly. Novel antireflection coatings make it possible to boost the transmittance both of coated and uncoated glass. Regarding materials interposed between the panes, the discussion includes gases and gas mixtures, coated plastic foils, silica aerogels, photochromic plastics, thermochromic cloud gels, and electrically switched liquid-crystal-based materials.