All About Solar Heat Gain Coefficient

Windows provide your home with light, warmth and ventilation. They can also negatively impact your home’s energy efficiency if you don’t do your research. You can easily reduce energy costs by installing energy-efficient windows in your home, or making improvements to the ones you already have. Knowing your windows’ solar heat gain coefficient (also called SHGC) is key to controlling your home’s temperature and to preventing damage to your property.

solar heat gain coefficient

Saving money isn’t the only guarantee that energy efficient windows can give you. They can also shield your home from the sun’s harmful rays and protect your belongings from permanent damage. Below is everything you need to know about SHGC and how to make sure your windows more energy efficient.

What is Solar Heat Gain Coefficient (SHGC)?

A technical answer for what SHGC is would be the amount of solar radiation admitted through a window. In layman’s terms, it’s the amount of ultra violet rays that pass through your window.

Just like when you suntan, there’s a difference between UV rays and sunlight. Sunlight can still enter your home, but UV rays can damage your floors, windows and furniture.

How Do You Measure SHGC?

Most companies display a window’s SHGC number, so you know what you’re getting before you buy it.  The SHGC is found by multiplying the shading coefficient by 0.87.

The shading coefficient is the old metric that window companies used to determine the thermal performance of a glass unit. The lower the number, the better solar heat gain coefficient your window has.

Why is SHGC Important?

When replacing your windows, solar heat gain coefficient can make the difference between a comfortable home and a miserable home. If the weather outside is sweltering hot and the sun is beating through the windows, your home will obviously become warmer.

SHGC determines the solar radiation that’s admitted through the window.  This information alone will help lowers your home’s overall temperature.

UV rays can damage your walls, floors and furniture just as they do your skin. If your windows have a high SHGC, the more UV rays will get into your home and cause damages.

A window that’s Energy Star Certified will lower your energy usage and save you money. Energy Star Certified products are clearly labeled with a blue sticker and awarded to the best of the best energy efficient products.

What is a Good SHGC?

The National Fenestration Rating Council (NFRC) is the governing body responsible for testing windows based on their energy performance. They use rating systems to measure your windows’ ability to help your home conserve energy and then provide the window with a certification.

The certification is based on the u-factor and solar heat gain coefficient. The SHGC has rating values 0 to 1 and for windows to receive the Energy Star, they must have a rating of 0.25 or less.

What is the Difference Between SHGC and U-factor?

U-factor indicates the rate of heat that’s transferred and shows how well the window is insulated regarding that heat. If the number is low, there’s little heat transfer and the window has a higher quality of insulation. Solar heat gain coefficient measures how well the window blocks heat from the sun.

two people relaxing by an energy efficient window

Any home with single-pane windows should consider replacing them to new double-pane windows with high performance, low-e glass. Always look for the NFRC label and blue Energy Star for certification.

Qualifying for Tax Credits

For windows to qualify for a tax break, both the u-factor and SHGC need to be equal or less than 0.3. You’re also required to have the manufacturer’s signed statement that the product complies with IRS requirements.

NFRC measures are based on the entire unit, not just the window glass itself. The NFRC label will list five measurements that help you judge how well a window will perform in a particular application.

Where you live affects which measurements are most important, but the tax credit requirements are the same across the country. The tax credit qualification requirement is 0.3 or less. The SHGC needs to balance with an efficient U-factor for your area.

Where Can You Buy With a Good Solar Heat Gain Coefficient

Purchase windows from a manufacture who sells energy efficient products and meets the recommended u-factor and solar heat gain coefficient in your climate.

They also need to have a reputation for excellent customer service and warranties for the unit. There are many organizations in which manufacturers can participate in to indicate that they care about the quality of their product and the product’s energy efficiency.

When you’re shopping for new windows, whether they’re custom or replacement, there are many things to consider. Looks are important, but energy-efficient windows will let just the right amount of light in without making your home to hot or too cold.

Always consider solar heat gain coefficient for your new windows in your home to help protect your belongings and save you money.

If you live in Chicago and need energy efficient windows with a great solar heat gain coefficient, then get a free quote from Feldco. Our high quality, vinyl windows are made to withstand Chicago’s unpredicatable weather and will keep your home comfortable no matter the temperature.

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