By James Piper, P.E.
When considering the environmental impact of windows, don’t overlook the effect of maintenance. All building components require maintenance, and windows are no exception. When properly maintained, windows can be expected to maintain their solar and thermal properties throughout their 30- to 35-year service life.
But neglecting maintenance on window components will result in a shortened service life and early replacement. Failing to properly maintain exterior surfaces will allow finishes to deteriorate and caulking to fail. Failed surfaces and caulking will allow water to enter, damaging the window and surrounding components. If the situation is allowed to continue uncorrected, it can result in the formation of mold within wall cavities or on interior surfaces surrounding the window.
Even with all the recent developments in window technology, manufacturers are looking for ways to improve performance even further. Some of these are available today, while others may be available in the near future. Most offer improvement in window performance by providing a mechanism to actively manage the window’s optical and thermal properties. In facility applications, these windows offer the potential of reducing a building’s peak cooling load by 20 to 30 percent while improving occupant comfort.
One of the new technologies available today is the motorized shade. When used as part of a building’s daylighting control, the units can provide an easy way to minimize solar heat gain in rooms with southern exposures. Controls for the units can be interfaced with room lighting controls or centralized building automation systems to regulate both light levels and solar heat gain.
One of the most promising developments is the “smart window.” Smart windows use a small electrical voltage to change the light transmission properties of the glass. Depending on the technology used, the windows can vary from translucent to reflective. By connecting the windows’ control to a building automation system, the properties of the window glazing for entire areas or buildings can be regulated to minimize heat gain or to maximize the use of daylight.