Aerogels are solids with high porosity (<100 nm) and hence possess extremely low density (∼0.003 g/cm3) and very low conductivity (∼10 mW/mK). In recent years, aerogels have attracted more and more attention due to their surprising properties and their existing and potential applications in wide range of technological areas. An overview of aerogels and their applications as the building envelope components and respective improvements from an energy efficiency perspective including performance is given here. This overview covers thermal insulation properties of aerogels and studies regarding structural features which will be helpful in buildings envelope. The improvements of thermal insulation systems have future prospects of large savings in primary energy consumption. It can be concluded that aerogels have great potential in a wide range of applications as energy efficient insulation, windows, acoustics, and so forth.

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CaCu 3 Ti 4 O 12 (CCTO)-silicone resin composites with various CCTO volume fractions were prepared. Relatively high dielectric constant (ε = 119) and low loss (tan δ = 0.35) of the composites with CCTO volume fraction of 0.9 were observed. Two theoretical models were employed to predict the dielectric constant of these composites; the dielectric constant obtained via the Maxwell-Garnett model was in close agreement with the experimental data. The dielectric constant of CCTO-silicone resin composites showed a weak frequency dependence at the measuring frequency range and the loss tangent apparently decreases with increase in frequency.