We know deciphering all those letters and numbers on your window labels can be stressful. However, understanding those terms can help you the next time you need replacement windows in San Francisco.
Put a Label on It
If your window has been tested for energy efficiency, it should have a label detailing its fenestration features. The National Fenestration Rating Council (NFRC) authorizes these labels for all units that are part of the Environmental Protection Agency’s ENERGY STAR® program. The NFRC labels allow you to compare products to help you decide whether they will be right for your heating or cooling needs. They include ratings, two of which we discuss in the section below.
Solving Solar Heat Gain Coefficient (SHGC)
Don’t let the complicated name scare you. The concept behind Solar Heat Gain Coefficient (SHGC) is actually pretty simple. This rating measures how much solar radiation a window allows to enter. The SHGC you want depends on many factors: your home’s location, the time of the year and the placement of the window, among others.
The lower the SHGC, the greater the insulation value. Windows with a lower SHGC rating transmit less solar heat and work best in an area with a warmer climate. A unit with a low SHGC rating will help keep cooling costs low on hot days. A value under 0.40 should suffice for this function.
Having a higher SHGC isn’t necessarily a bad thing. It simply means that the unit works better at collecting solar heat than deflecting it. It makes sense to install them in colder areas.
Understanding U-Factor
It’s not only the sun’s rays your San Francisco windows affect. U-factor generally refers to the overall energy efficiency of the window assembly, which includes the window frame, glazing and spacer. This rating tells you how well the unit insulates. Energy-efficient units have low U-factor values. When the rate of heat transfer is low, a window lets out less warm air on cold days. For homeowners in the North-Central region, we recommend choosing units with U-factor ratings lower than 0.35.
If you still don’t understand these ratings, don’t worry! The experts at Renewal by Andersen® of San Francisco are here to help. Turn to us for assistance in selecting energy-efficient replacement units. Give us a ring at (866) 609-5033 to schedule an in-home consultation and let’s discuss the most suitable windows for your situation.
