A u-factor is a measurement of the efficiency of a window or door. When considering a window purchase, it should be a key deciding point when choosing your windows.
Some people may think a window is just a window. That’s like saying a coat is a coat. While it’s technically true, you wouldn’t want to walk out into a Wisconsin blizzard with the same sort of coat you might wear while walking your dog in Florida. It’s the same thing with windows, but unlike a coat, you can’t tell just from looking at them how efficient or not efficient they are.
That’s where u-factors come in. A u-factor is a number assigned to a window by the independent National Fenestration Ratings Council. Also known as the NFRC, these ratings will tell you how efficient he window you purchased is. A word of caution. Some manufacturers and even some authorized dealers will stretch the truth when it comes to marketing their products with u-factors. What you need to find out is what the u-factor is on the windows you are looking at. It won’t do you much good to be told that a company has a great u-factor when you later find out that the testing was done on a 12 inch by 12 inch picture window and you are basing your entire purchase decision on the u-factor of a window that you’re not even putting in your house.
The federal stimulus package which covers window and doors purchased and installed through 2010, allows you to receive back 30% of the cost of your new windows up to $1500 as a tax credit as long as they meet two simple requirements. First they must have a u-factor no higher than .30 and a SHGC (Solar Heat Gain Coefficient) of no more than .30
When your windows are installed, you should look for the factory applied stickers on the glass of your windows. These stickers will feature the NFRC u-factors. Keep those stickers as they will act as proof for the government that the windows you purchased qualify for the federal stimulus tax credit.