We’re nearing the end of the winter season and transitioning into the summer months. What better time to reflect upon that magical combination of SHGC and southern facing windows and how a proper selection of window could have actually generated heat for your home all winter long. The matter of fact is that there is a sort of harmony where a window is actually generating more heat than it’s releasing during the winter month. How this effect is generated is a bit beyond the scope of this post but I’ll cover the basics for you below.

First, SHGC or (Solar Heat Gain Coefficient) is a important measurement displayed on the Manufacturer rating system. It’s purpose is to measure the heat transmitted from the sun blocked by the windows.

For cold weather climates where temperatures fall low enough, the SHGC for southern facing windows can actually best perform if it’s not at it’s lowest values. A low SHGC, where very little solar heat is transfered through the window would be a .30. A higher SHGC, where more heat is permitted through the window might be .50.

Our northern neighbors have a easier time determining when a SHGC should be higher or lower for the best energy efficient windows. The increased time during colder temperatures increases the significant changes a high SHGC can provide. In Colorado, this becomes more varied since your home may be too hot during fall and spring when a south facing window permits a lot of heat into the home that then must be cooled.

If you’re buying. A higher SHGC without sacrificing your U-value for southern windows should improve your energy savings over a low SHGC window. Consider a .50 SHGC or slightly higher effective at generating heat for your home in the window while maintaining a minimal difference. With a higher SGHC, during summer months you’ll pay a slightly higher cooling bill to offset the additional heat permitted to radiate through your window. The extra cooling costs in the sumer will be outweighed by the savings to heat your home in the winter.

For north facing windows, the SHGC rating of those windows isn’t worth worrying about as much. If you’ll be buying a different glazing or option for windows on different sides of your home you’re likely to save money by having a higher SHGC on northern windows. A higher SHGC is neither harmful or helpful for northern windows. Overall buy the northern windows according to what price will make the most sense.

For more information: Check this great post on Green Building Advisor.com

Have you ever considered the effects SHGC might have on your windows and winter heating costs? Did you realize you might save more money over a year with higher SHGC ratings rather than lower? Let us know! Post in the comments.