What is SHGC and why do I care?

Before buying new windows for your home you should check out the NFRC label. The NFRC, or National Fenestration Registration Council, is a nonprofit organization whose goal is to provide uniform, accurate information about the energy performance of windows. The easiest way to compare windows on a fair and equal basis is to look for the NFRC label. One of the most important ratings on this label will be the SHGC or Solar Heat Gain Coefficient. A good SHGC rating is important; especially here in New Mexico where air conditioning bills are a big deal.

The Solar Heat Gain Coefficient, SHGC, measures how well a window blocks heat from the sun. Therefore, the lower the SHGC, the lower the amount of heat gain. A window with a low SHGC rating will reduce the amount of heat that comes in through your windows from the outside. We know that our afternoon sun can be murderous, especially in the summertime. A window with a low SHGC cuts down that heat significantly and means lower cooling bills.

The SHGC rating on the labels is shown as a number between 0 and 1. The lower the number, the better the window is at blocking solar heat. Low-E glass is the hero here. Low-E glass has a coating that reflects heat back to its source. So the better the glass is at reflecting heat the lower the number will be on the sticker.

2015 NFRC labelRight now to meet Energy Star ratings in New Mexico the window must have a SHGC of .30 or lower. At Glass-Rite all of our vinyl windows meet this requirement or beat it with their standard glass. There is a variety of glass with Low-E coatings on the market, and some are designed to focus on reducing heat, others focus on reducing cooling, and some are good at doing both.

The purpose behind a Low-E glass that is good at reducing heat and cold is to keep the room at a more constant temperature. A comfortable constant temperature means you run your appliances less. This is especially important to us here in the summertime. A window that keeps the cooled air inside the house instead of passing through the glass to the outside is a window we want!

So when you are shopping for new windows for your home look for that NFRC label. If a window does not display a label, or has a number that is a little high, you may want to rethink your choice. The SHGC rating is an important part of a replacement window and it’s worth checking out the number to make sure you’re getting a good product. To learn more, or to see our choices of Low-E glass, please visit our showroom or give us a call to set up a free no-pressure estimate.