To provide some guidance to the victims of hurricane Andrew in Dade County, we performed a study of various types of modern glazing systems that might be incorporated in windows for south Florida residences.
The dominant energy impact of residential windows in south Florida comes from the solar radiant heat gain entering these windows and the corresponding heat loads on cooling systems. Thus any extra dollars spent by homeowners to purchase improved replacement windows should be spent in lowering the solar gains of the windows purchased (by reducing glazing shading coefficients or by adding exterior shading devices or vegetation) rather than increasing the window's resistance to conductive heat transfers. Consequently our recommendations say more about the choice of the single pane glass used in replacement windows than about the frames and insulating characteristics of these windows.
The situation is more complicated than this, however. Windows are not appliances where it is possible to offer a simple single-number energy performance rating. Windows provide view, illumination and aesthetic qualities, and can be sources of wanted or unwanted sound transmission, air leakage, glare, and thermal discomfort, as well as energy costs and benefits and additions to the electric company's peak demand. Some glazing systems provide enhanced protection against intrusion by wind-blown objects and burglars. Others offer improved shatter resistance and protection from injury by large pieces of broken glass. The proper selection of a window should consider all of these factors and optimize all the window properties for the specific application. An additional complication is that not all rebuilding following the hurricane involves total window replacement. In some cases the old windows are still intact and viable and energy-efficient retrofit recommendations are needed for these cases.
Buildings - Windows
Florida Solar Energy Center and McCluney, Ross, "Selecting Windows For South Florida Residences" (1993). FSEC Energy Research Center®. 834.