If you’re thinking about new windows for your home, you may have seen the term solar heat gain coefficient (SHGC). But what does SHGC mean for your windows, and why does it matter? In this blog post, Renewal by Andersen® explains SHGC ratings and how they can help you choose the right replacement windows for your home.
SHGC is one of the main factors that affects your windows’ energy efficiency. It measures how much solar radiation, or sunlight, a window lets into your home.
SHGC ratings use a number between 0 and 1. The closer the number is to 0, the less solar heat enters your home. For example, a window with an SHGC of 0.25 lets in less solar heat than a window rated at 0.50.
The rating measures more than sunlight that passes straight through the glass. It also includes solar energy the window absorbs and releases into your home as heat. This makes SHGC helpful for understanding solar heat gain, but it doesn’t tell you everything about a window’s energy efficiency.
You’ll often see SHGC and U-factor when comparing energy-efficient windows, but they measure different things. SHGC tells you how much solar heat comes through a window. U-factor measures how easily heat moves through the whole window. With U-factor, a lower number means the window does a better job of resisting heat flow.
Think of SHGC as how your windows handle heat from the sun. U-factor tells you how well the window insulates your home. Looking at both ratings gives you a better idea of how replacement windows may perform.
A higher SHGC rating means more heat enters your home, which is often helpful in colder climates. A lower SHGC rating means less heat gets inside, making it a better fit for warmer climates.
In places with warm summers and cold winters, you’ll need the right balance. The right SHGC rating can help keep your home comfortable throughout the year.
During colder months, a higher SHGC rating lets more warmth from the sun enter your home and may reduce the need for heating. During warmer months, a lower SHGC rating can help keep extra heat outside.
Two windows in the same home may get very different amounts of direct sunlight. That’s why the direction each window faces can affect which SHGC rating works best.
East-facing windows usually get more direct sun in the morning. West-facing windows can get stronger sunlight in the afternoon. South-facing windows may get plenty of sunlight throughout the day, though this changes with the seasons. North-facing windows usually get less direct sun.
Window size also matters. A room with a large area of sun-exposed glass may handle solar heat differently than a room with a smaller window. Looking at each window’s location helps you choose glass that fits that part of your home instead of using the same option everywhere.
Direction isn’t the only thing that affects how much sunlight reaches a window. Trees, roof overhangs, covered porches, nearby buildings, and other features can shade your windows at different times of day.
For example, two west-facing windows may point in the same direction but get very different amounts of afternoon sun if a large tree shades one. Looking at the actual sunlight along with the direction helps you understand how much solar heat each window needs to handle.
The National Fenestration Rating Council (NFRC) label gives you standard ratings that make windows easier to compare. You’ll find SHGC on this label along with other measurements, such as U-factor and visible transmittance.
Visible transmittance, or VT, measures how much visible light comes through a window. That’s different from SHGC, which measures solar heat gain. Knowing the difference can help you understand that natural light and solar heat aren’t the same thing.
When comparing windows, look for the whole-window SHGC rating. This rating covers the complete window instead of measuring only the center of the glass. That gives you a more useful way to compare complete window products.
Choosing the best SHGC rating for your replacement windows isn’t the same for every home. Your home’s layout, window size, shade, and insulation can all play a role.
With your local weather, energy efficiency, and home comfort in mind, talking with a window replacement specialist can help. They can look at your home’s needs and recommend an SHGC rating that makes sense for you.
If you’re ready to upgrade your windows and want expert help, talk with Renewal by Andersen. We can help you find windows and doors that fit your home and needs. Explore our double-hung windows, bow and bay windows, casement windows, sliding windows, picture windows, awning windows, and specialty windows. You can also learn about our entry doors, patio doors, and storm doors. If you’re in Seattle or Bellevue, WA, call (206) 775-7533 or schedule your consultation online.
