Energy Performance Ratings on Replacement Windows

So much focus is put on energy performance. But climate regions vary across the United States. So the National Fenestration Rating Council (NFRC) has come up with a label designed to help contractors and homeowners choose products that meet their energy performance needs. Looking at the NFRC label on replacement windows in Portland, OR can help ensure windows will perform well in a certain climate. But customers need to know and understand what they are looking at. Here is a brief breakdown  

 

U-Factor 

The U-factor is one of the most prominent ratings on an NFRC label. It is very similar to the R-value on insulation products, measuring the product’s level of insulation. The U-factor measures thermal transmission through solid materials like metal, vinyl, and glass. The special coatings and glazing technologies on replacement windows will largely determine the U-factor. Because no material can completely block heat transfer, these ratings usually fall between 0.2 and 1.2. The lower the U-factor, the more efficient the product is. 

 

Solar Heat Gain Coefficient (SHGC) 

The U-factor and the SHGC are very similar. But the SHGC measurement is directly related to how well the material stops solar heat from the sun. The values of SHGC go between 0 and 1. A low SHGC means the windows block a lot of heat from the sun. These types of windows work well in regions in the south where outside heat can have a significant impact on cooling costs. But a higher SHGC isn’t always a bad thing. In colder climates, solar heat can help warm the home and save on the cost of heating.  

 

Visible Transmittance (VT) 

These ratings are essential for understanding how much natural light comes through the windows. In the past, windows that were good insulators often blocked a lot of visible light. But glazing technologies have come such a long way. Now windows have glazing options that block radiant heat but do not block the visible light. Again, the VT ratings are between 0 and 1. The higher the number, the more visible light you have. And a high VT does not correlate to warmer room temperatures.  

 

Air Leakage (AL) 

As the name suggests, this rating measures the amount of air that passes through the window. And again, there is no way to completely stop air from coming through the window. The ratings range from 0.1 to 0.3. Air leakage is even more important in windy areas.  

 

Condensation Resistance (CR) 

This rating shows how well a window resists the formation of condensation on the inside pane. Measurements range between 0 and 100. And while the measurement does not predict the rate of condensation, it helps give customers a point for comparison. The higher the number the better the condensation resistance.  

 

For more information about reading the NFRC, contact the window experts at EnergyGuard Windows & Doors. They can help you navigate the energy labels and compare the top of the line products so you can find the best replacement windows in Portland, OR.