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How to Decipher Energy Labels on Replacement Windows

While the climate is mostly mild in Contra Costa and Alameda counties, windows can do a lot a lot to mitigate unwanted heat gains and losses. But first homeowners need to understand how to read energy labels. This is the only way to compare the energy efficiency of different windows. And because replacement windows in Freemont, CA are such a lofty investment, homeowners need to make informed decisions. These tips will help make sense of the letters and numbers on energy labels and help homeowners find the right product for their homes. 

What is the NRFC? 

The National Fenestration Rating Council (NFRC) is a non-profit organization that tests products and establishes objective energy performance ratings. Efficiency matters because it can save homeowners as much as 30 percent on their energy costs. These ratings allow customers to compare products head to head. Understanding them is the best way to make informed purchase decisions on replacement windows for a certain climate. The measurements to know include:


This measurement tells customers how well a product keeps heat from escaping. Lower ratings mean the product is better at keeping heat in. Measurements range from 0.20 to 1.20. This isn’t always a top concern for homes in Freemont, CA but can help in colder months of the year. A good U-factor rating for the area would be approximately 0.4 or 0.5. 

Solar Heat Gain Coefficient (SHGC)

This measurement rates how well a window blocks solar radiation. Ratings go from 0 to 1 and lower numbers mean less solar heat gains. Lower numbers will minimize the need for air conditioning in the summer and help reduce energy costs. 

Visible Transmittance 

This measurement tells homeowners how much natural light gets into the home. Lower VT ratings mean a room will be dimmer, and higher VT ratings mean there is more natural light passing through. In the past windows with a high VT also usually had a high SHGC. But modern technologies and specialized coatings can boost visible transmittance while reducing solar heat gain. 

Air Leakage

This number shows how much air passes through a window frame in cubic feet per minute per square footage. Low numbers mean the window is more airtight. This can be a valuable rating if homeowners are choosing replacement windows for a windy area. 

Condensation Resistance

This last measurement has ratings from 1 to 100. Lower numbers mean more condensation is likely to build upon the surface between window panes. Higher numbers mean better condensation resistance, which is important for humid areas. 

Just because there is a blue and yellow Energy Star sticker on certain products does not mean they are the most efficient on the market. It only means they meet the minimum standard for the area. Contact the experts at Quality Windows and Doors to find the best replacement windows for Freemont, CA. Call (925) 484-1747 to schedule a free consultation or stop by our showroom located at 3732 Stanley Blvd. Ste. B, Pleasanton, CA 94566. 

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