Will new windows really save you money by keeping your house warmer in winter and cooler in summer? Yes, and you can even measure a window’s performance. An independent national organization called the National Fenestration Rating Council (NFRC) conducts laboratory tests on windows to measure and rate several factors that affect thermal performance. Look for the NRFC label on any window you buy for your home or commercial property. Here is what you will discover: U-Factor: this shows how well...