Solera Transparent Insulation

Transparent insulation was developed to increase the thermal performance of glazings without significantly reducing the light transmission. One pioneer in transparent insulation, Dr. K. G. T. Hollands of the University of Waterloo in Ontario, was initially looking for ways of improving performance of solar water heating collectors. By creating a honeycomb matrix of transparent film between two layers of glazing, small air pockets are created that effectively block convective currents. One of Hollands’ doctoral students, Douglas Milburn, went on to found a company to commercialize this concept: Advanced Glazings, Ltd. After pursuing markets in the passive solar and commercial greenhouse industries, the company shifted its focus to commercial daylighting and in late 2000 introduced Solera®.

Solera is referred to as a translucent glazing unit (TGU). Two layers of glass are separated by 2.5 inches (64 mm), and the interglazing space is filled with honeycomb transparent insulation made from clear acrylic film. Because of the geometry of the transparent insulation—optimally sized honeycomb channels are formed that are perpendicular to the glazing plane—both convective and radiative heat loss through the glazing are significantly reduced. Less than 5% of heat flow through Solera glazing is due to convection, according to Milburn, while convective heat flow through conventional glazing—in which there is an unbroken air space the area of the glazing unit—is far greater. The honeycomb structure effectively suppresses heat flow no matter what the pitch of the glazing—from horizontal to vertical, says Milburn.

The listed U-factor for Solera is 0.25 to 0.20 (1.2 to 1.4 W/m2·°C). Neither low-e coatings nor low-conductivity gas fill (such as argon or krypton) are required to achieve this exceptional energy performance. Because air is used in the Solera TGU, risk of lowered energy performance if the gas leaks out is not a worry. A capillary tube in the Solera TGU is part of the “equilibrium moisture dynamics” system used to prevent moisture condensation and equalize pressure inside the TGU. This approach also eliminates risk of breakage or seal failure if the product is shipped over high-elevation passes—a problem with sealed insulated-glass units (see