Guide to Energy Ratings for Windows and Doors

Around the Delaware and New Jersey area, where both heating and cooling are almost equally important, energy-efficient windows and doors have an appreciable effect on your comfortable and expenses. Energy ratings make it easy to find models that do more than just look good.

U-factor — One of the most useful energy ratings in our cold-winter climate, U-factor indicates how well a window or door insulates. The lower the number, the more effectively the model insulates. Around Delaware, look for a U-factor of 0.4 or less. To become Energy Star-qualified for our area, a window must have a U-factor of 0.3 or less and an opaque door needs a U-factor of 0.17 or less.

Solar heat gain coefficient (SHGC) — This rating tells you how much heat from the sun the window or door transmits to the indoors. A lower number means less heat gets in. If keeping your home warm is your main concern, go for the highest SHGC you can find. If you often run your A/C in summer, however, look for a SHGC of up to 0.4. If you need cooling only occasionally, you’ll do well with a SHGC of up to 0.55. Energy Star-qualified windows in our area will have a SHGC of 0.4 or less, while no rating is required for opaque doors.

Visible transmittance (VT) — A rating given to windows and doors with windows, VT tells you how much light a design lets through. The higher the number, the more light you’ll see.

Air leakage — Although this is one of the less important energy ratings, it can still tell you something about how comfortable the window or door will keep you. The rating indicates how much air the design lets past, with a lower number indicating greater airtightness. Standard building codes call for a rating of 0.3.

At Sobieski Services, Inc., our goal is to help our customers in Delaware, Pennsylvania, Maryland and New Jersey learn more about energy and home comfort issues — especially HVAC and plumbing issues — so that they can save money and live in healthier, more comfortable homes.

Photo Credit: Alex L’aventurier, via Compfight cc