Windows that obstruct ultra-violet radiation reduce fabric fading. Pick windows which provide high UV protection. Expect to locate windows off-the-shelf that block greater than 75 percent of the UV energy. Some producers use the Krochmann Damage Function and UV transmission values to speed a window’s ability to restrict fabric fading potential.
This might just be the value at the middle of the glass. Do not settle for high glass worth. Start looking for “whole-window” worth of U-0.33 or better. Windows with low U-values are commonly available in most styles. Some manufacturers extend low-e coated plastic film inside the gas-filled airspace of double-glazed components to give an effective third or fourth “pane”. These components are expensive, but these high tech models can be more energy efficient than partitions in very cold climates. The R-value is lower than a normal wall, but if the triple-glazed units are designed with a high SHGC, they may be net energy gainers in certain layouts.
If you have lived in a cold climate, you have seen condensation and even suspend windows. No surprise. The advantage is where most double-paned glazing is held apart from aluminum spacers. Aluminum spacers are highly conductive, so the coldest portion of a glazed unit is about its borders. Moist conditions support the growth of mold, decay and collapse of finishes. Condensation affects durability and relaxation. Warming the borders reduces the chance for condensation to form.
It’s virtually impossible to construct a window which does not have a thermal bridge. But the material and form of the material used to produce the spacer can substantially affect the speed that heat travels through a window edge. Many window manufacturers now offer warm-edge spacers as standard fare. Conventional aluminum spacers aren’t acceptable! The best windows utilize less reflective materials such as thin stainless steel, plastic, rubber and foam. But more to the point, condensation is reduced. These spacers raise the advantage temperature by approximately 5 degrees. What is significant is that the window you purchase includes a warm-edge spacer system. And if you’re worried that the argon gas will flow out of the window, all signs are that a properly constructed seal will easily last 20 years.