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There are more than a dozen different window styles to choose from. There are multiple glass treatments to select and several different levels of insulation to decide on. You may have heard about thermal windows but are unsure of what they are. Thermal windows can be an excellent investment for your home. Find out the difference between a standard window and a thermal window. You might even already have thermal windows in your home.

What is a Thermal Window?

A thermal window is a window designed to have a lower U-factor than most standard windows. The U-factor of a window is the speed in which heat is lost through the window. The higher this value is, the less efficient the window. Windows with the lowest U-ratings are known as thermal windows and they are designed to keep heat in or out depending on the season.

What are the Benefits of Thermal Windows?

The major benefit of thermal windows. They are designed to increase and preserve the heat that your home absorbs from sunlight in the colder months. In warmer months, they keep heat out more effectively and reduce your your cooling costs. Either way these windows can make a significant different in energy costs for your home as most energy efficient windows will offer.

Cut Down on the Noise

Thermal windows come with the added benefit of being more soundproof because they are always in the form of double or triple paned windows.

Should Gas Be Added?

Thermal windows are available with different filler gases. They can be filled with argon or krypton gas to give them a lower U-factor. Take a look at the U-factor of each window before the gas is added and then look at the difference after the gas is added. According to energy guide you could see a u-factor drop by over .1 when adding the gas, which is a significant jump in efficiency.

Special Thermal Coatings

There are special thermal coatings known as low-e or low emissivity coatings on the market today. They’re designed to effectively reflect heat energy either back into the home or away from the home. According to Efficient Windows Collaborative a clear sheet of glass only reflects about 16% of heat energy. Windows with a low-e coating can reflect up to 96% of heat energy. While most of the coatings are less effective than that in practice since they aren’t as dense, they can still make a significant difference compared to standard clear glass.

In colder climates, heat is allowed through the windows and then trapped inside and in warmer climates heat reflected.

A contractor installs a thermal window into a home

How to Find Quality Thermal windows

To find good quality thermal windows there are a couple different ratings that you should be aware of. Both the U-value of the window and the SHGC (Solar Heat Gain Coefficient) are important. The U-value of a window dictates how freely heat can move through the window from one side to the other. A high U-value means that heat can move freely and a low U-value means that heat is being kept in or out depending on the need.

The SHGC is the amount of heat light allowed into the home. A high SHGC allows most of the heat light into your home to warm it up, while a low SHGC would keep most of it out to keep your house cool. While you want a low U-value no matter what type of climate you live in, the SHGC level you want depends on where you live. In hotter climates you want a low SHGC rating and in colder climates you want a high SHGC rating to help bring in more infrared light to heat your home up.

Beware of Highly Tinted Windows

When you’re shopping for these windows you also need to pay attention to the VT or visible transmittance rating of the window. When special tinted layers and coatings are added to the window they distort your view of the outdoors and reduce the amount of natural light coming into your home. The VT rating of the window signifies how much light can pass through and how bright your home will be. When a rating is very low you will be blocking out light which might be perfect for certain rooms, like a home theater. Pay attention to the VT rating as you shop for thermal windows to make sure you find a window that fits your needs.

Hopefully you have a better understanding of thermal windows now. Many of the windows on the market today could be considered thermal windows. Anything with an ENERGY STAR label on it is probably considered a thermal window as well. They’re generally a good investment but they are more expensive overall. Consider the benefits and then decide if you want to spend the extra money on these windows.