Apr 18 , 2023

All About SHGC


Are you considering replacing your windows or installing new ones? Or perhaps you are just curious to learn more about their energy efficiency. In such cases, it is essential to understand the SHGC or Solar Heat Gain Coefficient.

The focus of this article is to look at the SHGC or Solar Heat Gain Coefficient concept. And go over various details, such as its rating system. You will also learn why it is so crucial to maintain your home's energy efficiency and what it measures. So, if you want to know all about SHGC, read until the end.

What Is SHGC?

Firstly, what is SHGC or Solar Heat Gain Coefficient? The SHGC, in a nutshell, monitors the amount of heat that is permitted to enter your house via your windows. Less heat enters your house, resulting in cheaper summer cooling expenses. It is also a result of a lower SHGC score.

The rating on a window label informs you of how efficiently the window deflects solar heat. A rating between 0 and 1 is shown, with a lower number signifying greater performance.

Why Is SHGC Important?

But why is SHGC important? So, it all boils down to your wallet and energy efficiency. It can significantly impact your energy costs by the amount of heat that enters your house via your windows. It is particularly true during the hot summer months.

A high SHGC rating for your windows indicates they let more heat into your house. It might force your air conditioner to work more to maintain the temperature of your house, which would raise your energy costs.

On the other hand, windows with a low SHGC rating will prevent ultraviolet rays from entering your home. As a result, your house will stay cooler, and your air conditioner won't be working as hard. Ultimately, this will greatly reduce your energy costs.

Additionally, it's crucial to consider the SHGC rating of your windows if you're planning to replace your windows or construct a new house. You may reduce your energy costs and improve the comfort of your house by selecting windows with low SHGC ratings. Also, it's good for the environment!

What Is the Difference Between U-Factor and SHGC?

Two key metrics used to assess the energy efficiency of windows are the U-factor and SHGC. Both numbers relate to heat transfer. However, they measure different types of heat.

The U-factor, which ranges from 0.20 to 1.20, measures the rate of non-solar heat transfer through the window, including conduction and convection. A lower U-factor indicates better insulation and a more effective window.

In contrast, SHGC counts the amount of solar heat that enters a space via a window. It includes the heat from the sun's rays and the heat the glass absorbs before reflecting back into the room. A value between 0 and 1 indicates SHGC, with a lower number signifying less solar heat gain.

The two measurements are crucial for several reasons. Windows with low U-factors are preferred in colder areas to retain heat inside the house, whereas windows with lower SHGC ratings are favored in hotter climates to lessen solar heat gain and maintain a cooler house. Nevertheless, a combination of low SHGC and low U-factor is preferable for maximum energy efficiency in all regions.

How Can the SHGC Value Be Reduced?

You can decrease the Solar Heat Gain Coefficient (SHGC) values of your window, sliding glass doors, French doors, and skylight's in several ways. Using exterior shade structures like pergolas, Venetian blinds, trees, and plants is one of the most popular methods. These Outside shading methods may effectively reduce the heat gained by limiting the solar heat entering the home.

Using Low-E coatings is another successful strategy for lowering the SHGC value. Low-E can significantly reduce the quantity of solar heat that flows through the glass. Low-E or low-emissivity coatings are which are essentially invisible when applied to windows.

These coatings are placed on the surface of the glass during manufacture and form from a thin layer of metal or metal oxide.

Moreover, Low-E coatings may be used on the interior of windows and doors to prevent or reduce the transmission of incoming solar radiation. This technique works well for situations when other shading styles are not appropriate. In the summer, Low-E films reflect between 70 and 80% of solar heat gain.

And they do this while retaining more than 50% of interior heat in the winter. In general, lowering the SHGC value may aid in lowering the heat gain via windows and doors, resulting in a more energy-efficient structure.

How Do These Values Determine Which Windows or Doors to Install?

Now that you know what SHGC is and why it is important, you might wonder how these values help you. How can you use these values to decide which window or door you should install in your home?

When selecting the proper window or door, consider the solar heat gain coefficient (SHGC). The SHGC informs you of the amount of solar radiation that enters your house via a window or door, converting it to heat.

Warmer Climates

For warmer regions, you should choose a window or door with a low SHGC rating. Typically, a rating between 0.06 and 0.31—is advised in warmer regions.

It is because it keeps the inside of the house cooler and reduces the need for air conditioning. Windows with this rating allow less solar radiation to enter.

Colder Climates

Conversely, a window or door with a higher SHGC rating would be preferable if you live in a colder region. It will trap heat in your home and keep you warmer. For this reason, an SHGC rating between 0.45 and 0.57 is ideal.

But bear in mind that there are more aspects to consider. Your home's orientation and the amount of outside shading have an impact on your SHGC.

For instance, even if you live in a cooler area, you may want to choose windows or doors with a lower SHGC rating. It is because if your property is situated such that it gets a lot of direct sunshine. And can lessen the likelihood of your house being uncomfortably hot throughout the summer.


Now that you know all about SHGC and how it may influence your chosen windows and doors. Remember that your home's ideal SHGC will depend on several factors, including your climate, orientation, and exterior shading.

Thus, get advice from a specialist before making any selections to ensure you choose the best product for your requirements.

All About SHGC

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