What Are the Most Energy Efficient Windows?
Last Updated: Mar 20, 2025Windows in a home play an essential role in both your sense of well-being and the energy required to heat, cool, and light your house. On the upside: large energy-efficient windows placed generously throughout the home can bathe your home in natural sunlight. It can reduce energy demand from artificial lighting during daylight hours. They offer a biophilic architectural experience that connects your home with the surrounding natural world and even naturally warms your home with the heat from the sun. However, inefficient windows can be a significant source of heat loss and gain for your home. It will cost you money on utility bills, and negatively affect your thermal comfort.
Below, we look at the important function that energy-efficient windows play in the home and offer a complete rundown of the most energy-efficient window types for your house.
Table of Contents
- The Role Energy Efficient Windows Play in the Sustainable Home
- What to Look for in the Best Energy Efficient and High-Performance Windows
- The Top 3 Most Energy Efficient Types of Windows on the Market Today (and What They Cost)
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What to Look for in the Best Energy Efficient and High-Performance Windows
When searching for the best energy-efficient and high-performance windows, there are several different factors you need to focus on:
- U-Factor: The U-Factor is the primary insulation rating for windows. It measures the rate of heat transfer, and generally speaking, the lower the U-Factor, the higher the insulation capability of the window. (Another way to think of it: the U-Factor is the inverse of the R-Value used primarily for insulation in walls and roofs. It takes into consideration both conduction and radiation for the entire window assembly.)
- Solar Heat Gain Coefficient (SHGC) Rating: This rating measures the amount of solar radiation emitted through a window, typically more prominent in southern, hotter climates. You can find information about how to choose windows with the maximum SHGC rating for your home here.
- The Glazing Package (number of panes): In much of Europe, triple pane windows are the norm for home construction and can lower the window's U-value by up to 50 percent. However, in North America, cost considerations often lead many homeowners to choose double pane windows, which have become the standard. While triple-pane windows might be the best option, double-pane options that rely on low emissivity (Low-E) glass are also a great option. It includes an invisible coating of metal oxide on one of the interior panes.
- The gas between the Glass: You should consider finding window options that fill the spaces with gasses such as argon, xenon, or krypton. It can reduce condensation and also increase the thermal performance of the window.
- Pane Spacers and Frame Materials: The pane spacers and frame materials are just as important as the glass itself when it comes to actual window performance. Pane spacers that contain little or no metal are known as warm edge spacers and can be much more energy-efficient. The frame materials can also affect the energy performance of the window. Although wood frames are the most natural and energy-efficient, they require maintenance and can lead to leaks. Composite frames that combine an inner timber frame covered with aluminum or plastic rely on wood while also reducing the need for maintenance.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
