Few things are worse than the brutal, scorching heat of summertime in the south. From buying fans and misters to simply staying indoors with the AC on full blast, the season seems to be a delicate balance of getting the right amount of sunlight versus avoiding it at all costs.
Windows play a huge factor in balancing heat levels inside your home. Whether you’re in the process of building a new home or looking to upgrade before Mother Nature turns the heat up, it’s important to consider the SHGC Factor for the windows you may be considering and how that rating will affect your comfort year round.
When shopping for windows, you may notice a National Fenestration Rating Council (NFRC)↗ label that shows a range of different ratings for things like U-Factor, Visible Transmittance and Air Leakage. In the top right corner of the label under Energy Performance Ratings, you’ll see a number between 0-1. That’s the Solar Heat Gain Coefficient (or SHGC Factor). This number measures the amount of solar heat that reaches a window against the amount of heat that filters through to the inside.
The best rating for your home is determined by the placement of windows (east vs west), varying low-e coatings, and the climate you live in, among other factors.
The best SHGC rating for your home is determined by the placement of windows (east vs west), varying low-e coatings, and the climate you live in, among other factors.
In warm climates, or in rooms with a tendency to overheat during the day, you’ll want to consider a lower SHGC rating (as low as 0.25 is considered good). In cooler climates, a higher SHGC rating is generally better (range of 0.42 – 0.63).
For a comprehensive look, here is the breakdown of acceptable SHGC ratings per climate zone, as indicated by the Efficient Windows Collaborative (EWC):
Discuss all of your options free of charge with a Brennan window specialist to ensure you’re getting exactly what you want for the best value. We have more than four decades of experience helping customers find the perfect window for their lifestyle and budget.
In short, yes. The tint or film on your window affects the SHGC Factor. For warmer climates, you’ll want to choose a film with a VT rating greater than the SHGC Factor. To make the best decision, divide the window VT Rating by the SHGC value. The higher the number, the more selective the film will be in filtering light in warm climates.
EWC Recommendation: If air conditioning is not a concern, look for a high SHGC (0.35-0.60) so that winter solar heat gains can offset a portion of the heating energy need. If cooling is a significant concern and no shading is available, select windows with a SHGC less than 0.32. Select skylights with a SHGC of 0.40 or less.
For more information on Solar Heat Gain Coefficient and other performance and energy ratings, review the Energy Star breakdown here↗.
A higher SHGC rating is generally better for cold climates, while a lower SHGC rating is generally best for warm climates. Although, there are many more factors to consider before making a purchasing decision. Talk to a specialist, and do your research.
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What if we told you windows could actually improve your health? Exposure to natural light offers a vast array of health benefits – more Vitamin D (for healthy bones), avoidance of seasonal depression, improved sleep and reduced risk of migraines and eye strain. By simply sitting next to a window with a high visible transmittance rating, you’re (literally) absorbing all the good stuff your window is allowing to filter through.
What is Low-E window glass? Low-E glass boosts the insulating power of your windows, learn more about how they work and what options are available in this post.