Transparent insulation materials: An overview on past, present and future developments

Transparent Insulation (TI) systems are regarded as one of the most promising technologies for providing thermal insulation along with transmission of solar energy. TI systems have a wide range of applications in energy conservation and harnessing solar energy. This paper provides an overview of TI systems and TI materials (TIM), by characterising TI systems on the basis of geometry, material used and general heat losses in these geometrical layouts. Evolution of TI applications is presented with the introduction of new materials. Two new types of TIM (polypropylene and cellulose acetate) are reported in this paper in contrast to previous reviews on TIM. A systematic survey of past literature was carried out to present latest research works and development on TI geometrical layouts and applications. An explicit study of TIM and TI system manufacturers has been carried out to show existing trends in TI applications and geometry. In the last decade, aerogels are most frequently used as TIM for providing insulation and daylighting in buildings. It is concluded that in existing TIM technologies, TI systems incorporating aerogel have the lowest thermal transmittance (U-value) and better solar transmittance (g-value) at lower thickness compared with TI systems incorporating other types of TIM. This paper highlights the availability of TIM geometry with desirable applications and TI systems for energy conservation.