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What Exactly is Low-E Glass?

This is a question we get a lot at Freelite windows and doors. In short, Low-E means low emissivity, or more specifically, low thermal emissivity. Glass is one of the most versatile building materials in use today. In part, it is because of the constant improvement in solar and thermal performance. Low-E glass can be used in both windows and doors and makes these exterior products more energy efficient. So, what is low emissivity glass and how does it work in windows and doors? Here is what you need to know.

By nature, glass is highly thermal emissive, especially clear glass. It transfers and absorbs a ton of energy without reflecting much. This means, if you have clear glass in your windows, your home is absorbing all that heat from the sun with very little acting as a buffer. It also means the windows don’t retain radiant heat from inside, so heat accumulated during the day is released back out at night.  That is why the house is so hot during the day—not something you want for a home in Scottsdale, AZ. You are using your cooling appliances more than necessary and paying more as a result. So, to improve thermal efficiency in a window, manufacturers apply a film coating to raw glass.

How Does Low-E Glass Work?

At a glass manufacturing plant, the coatings are designed and applied to one or more surfaces of a glass unit. Usually, windows and doors with double panes have a coating on the inside of the outer pane. The coating is designed to reflect radiant infrared energy.  So it lets in visible light, but keeps the energy on the same side it originates from. Say the sun shines on a Low-E coated window. A lot of the energy gets reflected back towards the outdoors instead of unwanted heat passing through the glass. The same goes for running your heater inside. When energy from the heater comes up against a Low-E window, the heat is reflected back inside the home. No unwanted heat is lost or gained.

What is the Process for Low-E Glass?

There are some unique methods used for coating glass. For hard coat, manufacturers apply pyrolytic coatings at very high temperatures. Usually, these are a tin dioxide, or a hard coat. Hard coat glass is considered medium grade for energy efficiency. And while the hard coat windows and doors are more durable, they do have a higher solar gain and run the risk of developing a slight haze over time.

The second method is Magnetron Sputtering. For this process, manufacturers place glass in a vacuum chamber and add several thin layers of silver with antireflective properties. This is a soft coat and must be enclosed between the panes to protect it. Soft coat is the most efficient Low-E glass and has the best performance, but the process also makes it more expensive.

Getting Low-E Windows and Doors from Freelite

Low-E glass is definitely the way to go in Scottsdale, AZ. Most companies will offer both hard coat and soft coat Low-E glass Scottsdale, AZ products. Regardless of what you choose, they will perform better than clear glass windows. Call us today at (602) 233-1981 or visit us at 331 W. McDowell Rd., Phoenix, AZ 85003 for a hassle free consultation and quote.