Windows are one of the most important energy saving or wasting features in your home. At Kwaske Construction, we believe that staying educated about new technologies available for maximum energy efficiency is essential for helping you choose the best windows for your home.
Below is some terminology and information that will be helpful for you to know in learning what is best for your windows*. The more information you have, the better likelihood that you will get the product and service you need from us.
U-factor tells you how well the window will insulate, or keep heat in (during the winter) or out (during the summer). The lower the number the better.
Solar heat-gain coefficient (SHGC) This number tells you “how well a window blocks heat from incoming sunlight” (Easley, 2011, p. 2). Again, the lower the number between 0 and 1, the better.
Visible transmittance (VT) is how much light comes through the window. It is again a number between 0 and 1.
Air leakage (AL) tells you a measure of air coming in. The lower the number, the less air is coming through.
Condensation resistance (CR) measures how well the window keeps from forming condensation. In this case, the number is between 0 and 100, and the higher the number, the better is the window from getting condensation.
Low-E (Low-emittance) refers to a coating manufacturers put on the window which helps prevent heat loss. There are also Spectrally Selective Low-E coatings, which allow sunlight in while blocking the sun's heat. They are categorized into high, medium, or low. Where you live in terms of climate will help determine from which category you will choose. Some windows are made with three or four panes with a low-E coating in each space.
A low-E window will help prevent fading of fabrics and artwork in your home as well. Low-E windows also have special gasses put between the panes to help increase performance. Check the manufacturer's warranty on gas retention.
It used to be that the spacers used between the panes were metal and caused condensation to form around the bottoms of the glass. More recently, manufacturers are using different materials that do not cause this problem. Low-E windows and certain types of glazing can also help reduce condensation formation. The humidity in your home has an impact on whether or not condensation will form on your windows. This can influence the kind of window you should purchase.*
Going from clear glass to low-E windows will pay off through heating and cooling cost savings and cessation of other issues such as condensation. Please call Kwaske Construction and speak to us about a quote for your next window replacement project.
*All information is taken from: Easley, S. (2011). Builder's guide to windows. The Journal of Light Construction, October, p. 1-7