What are the benefits of triple-pane windows?
Weighing the costs and benefits of upgrading to triple-pane glass? We’ll walk you through what you need to know in order to make the best choice for your project.
In short, windows and doors made with triple-pane glass give you greater thermal and sound performance. Read on to understand more about the difference triple-pane glass makes and how it compares to standard dual-pane glass — plus, get to know your options.
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How do triple-pane windows make a difference?
The specific performance benefits of windows with triple-pane glass include:
- Improved insulation: A window with triple-pane glass will be more insulating than a window with standard dual-pane glass. The additional pane of glass and additional air space combined with opportunities for multiple Low-E coatings slow down the transfer of heat.
- Reduced sound: Windows with triple-pane glass will almost always outperform windows with dual-pane glass from a sound perspective. This is because they’re thicker. The thickness of the two air spaces and three panes of glass slow down the transmission of sound.
How is thermal performance measured?
The thermal performance of windows and doors is measured with U-Factor values. Looking at a window's U-Factor value will help you compare between manufacturers and understand if the performance will meet standards for various energy-efficient building programs.
It’s important to look at the U-Factor value for the entire window assembly — glass, frame, etc. — when assessing performance. To do this, look for the “whole unit” U-Factor value rather than the “center of glass” U-Factor value. It’s particularly important to look at U-Factor performance when you live in a cold climate because it will help you understand how well the unit will help keep in warm air during the winter. (In a hot climate, Solar Heat Gain Coefficient would be the thermal performance value to evaluate because it gives an indication of how well the unit will help keep the sun’s heat out).
What’s the difference between R-Value and U-Factor?
- R-Value is a measurement of resistance to energy (or heat) flow, with larger numbers indicating better resistance. In other words, a window’s R-Value is a measurement of how well the window keeps heat from escaping the home, or how insulating the window is. Although both measures relate to thermal performance, it’s most common to see R-Value used to measure wall assemblies and U-Factor to measure window assemblies.
- U-Factor is the inverse of R-Value. Instead of measuring resistance to heat flow, it is a measurement of heat loss, with smaller numbers indicating a slower rate of loss. U-Factor is also the measure used by the National Fenestration Ratings Council (NFRC), which is a nonprofit organization that has established window, door, and skylight energy performance ratings.
Want to understand more about the difference between R-Value and U-Factor values?
How is sound performance measured?
The measures used to evaluate sound performance are sound transmission class (STC) and outdoor-to-indoor transmission class (OITC). A higher value indicates better sound reduction for both STC and OITC. We provide STC and OITC ratings through the testing we do — find performance documents.
How do Low-E coatings improve triple-pane glass performance?
The more coatings applied, the better the thermal performance will be. Low-E coatings can be applied to triple-pane glass in various ways. Here’s what you should know:
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2. Enhanced triple-pane glass (two Low-E coatings)
Enhanced triple-pane glass options include two surfaces with Low-E coatings, which further enhances thermal performance. Here are some combinations to be aware of:
- Low-E4 Enhanced Triple-Pane Glass has one pane with Low-E4 coating plus an additional Low-E coating on another light of glass. This combination of Low-E coatings helps windows perform well in all seasons while also allowing the warmth of the sun to help heat the home. It’s a good option in northern climate zones.
- Low-E4 SmartSun™ Enhanced Triple-Pane Glass has one pane with a SmartSun coating plus an additional Low-E coating on another light of glass. This combination helps keep homes cool in summer and warm in winter, with the added benefit of blocking 95% of harmful UV rays. It’s a good option where there are both heating and cooling bills along with lots of direct sunlight.
- Low-E4 PassiveSun Enhanced Triple-Pane Glass has one pane with a PassiveSun coating plus an additional Low-E coating on another light of glass. This option helps improve thermal performance while avoiding a lot of tint. This enhanced version of triple-pane glass allows in the most heat from the sun’s waves, so it’s a good option for passive homes or homes designed to handle higher solar heat loads in the northernmost climate zones.
