The Difference Between Window U-Value and SHGC Ratings

When choosing new replacement windows for your home, one of the most important things to keep in mind is energy efficiency. Thanks to advancements in window technology, energy-efficient windows help ensure your indoor living spaces remain comfortable while lowering your home’s monthly energy expenditures. However, shopping for energy-efficient windows can be confusing, especially if you don’t know energy ratings.  

U-value and solar heat gain coefficient (SHGC) ratings are two ratings you might notice on stickers and fliers that come with replacement windows. Read on to learn the difference between the two. 

U-Value Rating

The window’s U-value rating, which is also referred to as U-factor, measures the rate the window transfers non-solar heat. This rating represents the insulation properties of your window. The U-value rating is between 0.20 and 1.20. The lower the U-value rating, the less heat gets transferred through the window glass. 

In general, finding a replacement window with the lowest U-value is optimal to help homeowners better utilize heating. In addition, you should also consider the climate where you live. For areas with unique microclimates, it’s crucial to look for a window with a U-value of 0.25 or less. Meanwhile, in foggier areas that require more heating, the U-Value rating of your windows should be as low as possible to lower the costs of heating bills. 

SHGC Rating

SHGC is a window rating that reflects the amount of solar heat that gets inside the home once it reaches the glass. This also includes the amount of sunlight absorbed by the glass and later reradiated to the room. The SHGC rating is measured between 0 and 1. The lower the SHGC ratings, the lesser the solar heat the glass allows from entering the house.

Keep in mind that SHGC and U-value ratings share a relative correlation. This means windows with higher SHGC ratings also have higher U-value ratings. For this reason, you also need to look for a low SHGC rating for optimal performance and lower costs. This includes a rating of 0.20 or less. If you like your home on the warmer side, however, you need an SHGC rating between 0.35 to 0.60 to allow natural solar heat in. 

Turn to Pressure Point Roofing, Inc. for high-quality window replacement services! We are proud to be an Energy Trust of Oregon Trade Ally Contractor, which means we strive to deliver significant clean energy benefits to our customers. Talk to us about incentives for upgrading your old windows. Call us today at (541) 772-1945, or fill out our online contact form to set an appointment. Our Oregon service areas include Grants Pass, Gold Beach, Eagle Point and Central Point.