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When choosing a skylight, Look Beyond Center-Of-Glass U-Factor

April 21, 2021

Choosing a Skylight

Center-of-glass (COG) thermal performance is a term that only industry experts can love, but which consumers begin to understand when they’re buying new windows and skylights. Also called the U-factor or the U-value COG performance values are just one way to measure the energy efficiency of a product. 

What Is COG U-Value?

The U-value (or U-factor) of a window is the rate of heat loss. Lower U-factor numbers correspond to better energy efficiency. Center-of-glass U-factor is the performance of the window glass (also called glazing) without the frame. In most cases, the COG U-factor will be lower than the window’s overall U-factor, because some energy is often lost through the connection between the frame and the glass. This makes the whole window U-factor a higher number than the COG U-factor. 

When Is Low U-Factor Important?

Low U-factors are most important in climates where winter heating is important for maintaining a comfortable indoor temperature. If you live in a climate where summer cooling is more important, U-factor is still a consideration, but other factors come into play to determine the total energy efficiency of the window. 

Why You Should Look Beyond COG U-Factors

Center-of-glass U-factors only tell part of the story in terms of a skylight or window’s energy efficiency. Glazing and frame must work together to provide resistance to heat flow. Installation methods, materials and design must work in tandem to seamlessly create an overall energy-efficient product. Whether the COG value is low or not, if the whole window U-factor is much higher, performance issues will still be present.

Signs Your Skylights Are Inefficient

If your home has older skylights, there are many signs you can look for that your skylights are inefficient.

  • Condensation appears on the skylight in winter.
  • A layer of ice or frost appears on the inside of your skylight when temperatures outside drop below freezing.
  • Water leaks and signs of water damage occur around the frame or on the ceiling near the skylight. 

Watch for these signs. Know when to replace your skylights. 

What VTECH Does Different

VTECH Skylights are created to be leak-free, including air leaks. Our solid-state skylights are all one piece, fused together by a chemical bonding process. 

We Use LoĒ³ 366 Glass

Made by Cardinal Glass Industries, LoĒ³ 366 glass includes a clear coat of silver on the surface to reflect heat into the atmosphere. This is the key to raising resistance to heat. Even while providing superior thermal insulation, LoĒ³ 366 also allows visible light to pass through the glass, to illuminate your home or building naturally. In fact, LoĒ³ 366 blocks up to 95 percent of UV rays. 

Our Frames Are Made With Reaction Injection Molding (RIM) Processing

The RIM process is the same process that your car company uses to make sunroofs that don’t leak in your vehicle. At VTECH, our RIM processing skylights are made from a combination of COLOFAST® Polyurethane and Isocyanate injected together into a mold to create the frame.

These two materials are our preferred materials because they’re long-lasting, durable, and capable of withstanding the harshest conditions. Whether you live in a climate that is subjected to freezing cold temperatures in winter or blazing hot summers, we’re confident our skylights are up to the task. 

Then It’s All Fused Together

We say our skylights are solid-state because we take that LoĒ³ 366 glass and COLOFAST® Polyurethane and Isocyanate frame and fuse them together in a chemical process. Ultimately, the glass and frame become all one piece, with no screws or caulking to hold it together.

That means no air leaks and low overall U-factor. And, because our skylights are all one piece, there’s No maintenance required to prevent air leaks. Whereas some skylights need regular inspections and recaulking to maintain their energy efficiency, VTECH skylights require little to no maintenance over the years.

They’re convenient and designed to maintain their energy efficiency throughout their service life. That’s why our products are protected by a 20-year system warranty. We tell our customers their skylights may outlast their roof!

Contact VTECH for Truly Energy Efficient Skylights

VTECH Skylights are designed to last and help your home stay comfortable, even at times of the year when the summer sun blazes down, or when the winter chill puts a deep freeze on your home. To find out more about how our skylights can improve your home’s overall performance and energy efficiency, contact VTECH today

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