How Replacement Windows Earn an ENERGY STAR® Label

Heat gained and lost through drafty windows account for 25% to 30% of residential heating and cooling costs, according to the Department of Energy. That’s why it makes financial sense to invest in energy-efficient replacement windows. 

How can you tell if a window is energy-efficient? By looking for the ENERGY STAR® label. Only windows that have met the government-run agency’s stringent performance standards can receive this label. 

How exactly do products like replacement windows earn an ENERGY STAR certification? Renewal by Andersen® of Knoxville, your local window contractor, explains in this guide.

General Criteria for Products 

 For a product to be considered for an ENERGY STAR certification, it has to meet the EPA’s criteria. These include: 

• The product must be able to contribute significant energy savings nationwide 
• Energy savings should be achieved using technology that isn’t protected as a trademark or under a brand name and can, therefore, be used by several manufacturers. 
• If an energy-efficient version of the product is more expensive than a conventional, less-efficient version, consumers should be able to recoup their investment through reduced utility bills over a reasonable amount of time. 
• The product’s energy consumption and/or efficiency can be measured through standardized testing. 

Criteria for Window Replacements 

What about window replacements? To get certified, a window replacement needs to be: 

• Manufactured by an ENERGY STAR partner like Renewal by Andersen 
• Independently tested by the National Fenestration Rating Council (NFRC)
• Meet the NFRC ratings and guidelines set by the EPA 

What Are NFRC Ratings? 

NFRC ratings are located below the ENERGY STAR label and tell you whether certain replacement windows are suitable for your area. Remember: One feature alone isn’t enough to make a window energy-efficient. You should take into account a window’s total performance—the NFRC ratings can help you do just that. 

Here’s an overview of the ratings: 

• U-factor – The U-factor indicates a window’s insulative capabilities. The higher a window’s U-factor, the better it can prevent heat transfer. 
• Solar Heat Gain Coefficient (SHGC) – The SHGC gives you an idea of how much heat from the sun can pass through a window. The lower a window’s SHGC, the less heat that can pass through its glass panes. 
• Visible transmittance – A window’s visible transmittance gives you an idea of how much sunlight can pass through the window glass. The higher the visible transmittance rating, the more natural lighting a window can provide. 
• Air leakage – As the term suggests, the air leakage rating indicates how much air can enter their homes through windows. The lower the air leakage rating, the fewer drafts a window will let in. 

What Are the Ideal NFRC Ratings for Temperate Climates? 

What are the ideal NFRC ratings for windows in areas with temperate climates like Tennessee? In general, most contractors would recommend choosing a window with a low U-factor and a high SHGC. The best place to install your new windows would be on the south side of your home. Since the south side receives the highest amount of sunlight, installing your replacement windows there allows you to take full advantage of natural lighting. For more on how to make the most of your new windows, consult your local window contractor. 

Here’s a tip: It’s important to choose a window frame material that can handle abrupt temperature changes. Some window frame materials expand when exposed to high temperatures and contract when temperatures plunge below zero. These repeated expansions and contractions can cause window damage. 

If you’re looking for a material that can handle cold and hot temperatures, you might want to try looking at our Fibrex® frames. Fibrex is a wood-and-vinyl composite that’s exclusive to leading window company Renewal by Andersen can maintain its rigidity and stability in all climates and has excellent insulative capabilities. 

Want to learn more about our Fibrex windows? 

Renewal by Andersen of Knoxville offers a wide variety of premium windows. What sets us apart as a window company is our Signature Service: We customize each window according to our customers’ needs and preferences, ensuring your windows will always be a great fit for your home. To schedule a free consultation, call us at (866) 609-5033 or fill out this form. We serve homeowners in Knoxville, TN, as well as the surrounding communities in Tennessee.