Advancing superwindows in the United States: overcoming technical and institutional barriers

摘要

Abstract: Simulation studies have shown that windows with total U-values under 0.8 W/m$+2$/-C and solar heat gain coefficients greater than 0.5 will admit more useful solar heat gain than they will loose by conduction/convection and radiation in virtually all locations in the continental United States, independent of orientation. Such fenestration products, when used in typical homes, thus become net energy gainers. Laboratory and field testing/simulations conducted as part of LBL's superwindow research program have proven that glazing systems with three glazing layers, two low-emissivity coatings, and the appropriate low-conductivity gas-fill can achieve this performance level. Beginning in 1990 several U.S. manufacturers started to offer such products commercially. However, laboratory and field testing, as well as computer simulations, have also shown that existing frame/edge designs and materials significantly reduce the total performance of windows using such superglazings. Current research focuses on the use of simulation tools and a high resolution laboratory infrared thermography imaging system to work with manufacturers to develop highly insulating frames and edges. !8