One quality to look for in new windows is energy efficiency, especially if you live in the St. Louis area where the summers are scorching hot and the winters are freezing cold. But shopping for energy-efficient windows is a bit more complicated than just purchasing the first window with an “energy saving” sticker on it.

Here are four features to look for when you’re shopping for windows that reduce your heating and cooling bills.

Low-E Glass

Heat travels very easily through a pane of glass. In the winter, this means that a lot of your costly heat is lost through the glass. In the summer, it means the warmth from outside is always seeping in through the windows, counteracting your air conditioner’s efforts.

Low-E coatings are materials that can be applied to the surface of the glass to reduce the rate at which heat transfers through it. (The “E” stands for emissivity, a measure of the rate at which heat is transferred through a material.) There are several kinds of Low-E windows, but in an area like St. Louis where the winters are cold, you want to look for the variety called passive Low-E windows. 

Passive Low-E window are made to allow short, infrared energy from the sun to pass through the glass, which will help keep your home warm in the winter. However, they reflect the longer heat waves back into your home, reducing heat loss and your heating bills.

In the summer, they block the longer heat waves from the sun while still letting in the shorter infrared waves, so your home still looks sunny in spite of feeling cooler.

Double- or Triple-Pane Glass

Double-pane windows consist of two sheets of glass with a thin layer of air between them. The layer of air acts as an insulator, greatly reducing the amount of heat lost through the glass. Most windows today are double pane, and they offer sufficient heat retention for many homeowners.

However, if you’re really dedicated to creating as energy-efficient a home as possible, you may want to opt for triple-pane windows, which have three sheets of glass with two layers of air trapped between them. By some estimates, they’ll save you about 2% to 3% on your heating bill compared to double-pane windows.

Argon Gas Filling

Another way window manufacturers make windows more energy efficient is to replace the air between the panes of glass with argon gas. Argon gas is a heavier than air, which makes it a better insulator. Your home will stay warmer in the winter and cooler in the summer.

As an added bonus, the argon increases the soundproof quality of the windows, which may be beneficial if you live on a busy street. The argon also slows down the corrosion of the window material, so your new windows won’t grow loose and leaky as quickly.

Fiberglass Frames and Sashes

It’s also important to consider the material around the glass in your windows. In many cases, if your goal is energy efficiency, fiberglass sashes and frames are the best option. Fiberglass contracts and expands at roughly the same rate as glass, so it stays in close contact with the glass as the temperature fluctuates. This means your windows won’t be as leaky, even after years of exposure to varying temperatures and humidity levels.

Fiberglass itself is also a rather poor conductor of heat, so you won’t experience as much direct heat loss through fiberglass sashes and frames.

In St. Louis, you need windows that keep the sun’s hot rays out in the summer and your home’s heat inside during the winter. If you look for the features above, you’ll be off to a good start. Stop by our showroom to see our various window options in person.