What is Low E Glass?
Posted on June 26, 2017 in Energy Efficiency
You might hear the terms ‘Low-E glass’ and ‘Low-E coatings’ frequently when you are researching your options for windows and replacement windows. They are increasingly popular as window tech, but what exactly is it? What does it do? And how does it differ from other coatings, such as solar film?
What is Low-E glass?
Low-E glass stands for low emissivity glass. It has a coating that helps block out a substantial portion of ultraviolet (UV) light and infrared (IR) light while allowing the majority of visible light to pass through. This is important because of the impact of UV light and IR light on your home:
- UV light is typically known for its role in causing skin cancer, which is certainly a good reason to be cautious of it, but that’s not the full extent of damage it can cause. It can also contribute to the fading of various materials - ‘bleaching’ things left in the sun.
- IR light is closely associated with heat energy - for the most part, the heat you feel from sunlight is the heat of infrared light. The exact relationship between infrared and heat is complicated, but it’s important to understand that controlling IR light increases control over the passage of heat through your window.
How does Low-E glass work?
Low-E coatings help you to block out the majority of UV and IR wavelengths of light while still allowing most of the visible light through your window. They also differ from something like a solar film in the manufacturing and application process. A Low-E coating is microscopically thin and is applied during the initial manufacturing process. It’s closely bonded to the glass to the point that you’ll struggle to notice it. But one consideration is that you can’t apply the Low-E coating after your windows have been purchased and installed. If you want Low-E windows, you need to purchase Low-E windows. As a bonus, Low-E glass is applied from the manufacturer, so there is no risk in the coating voiding your warranty, which can happen with solar film.
In cold weather, Low-E glass can also help with energy efficiency by reflecting heat back into the home, helping to maintain warmth. In warmer months, it reflects heat away from the home, keeping it cooler. Blocking UV rays helps to prevent fading that can damage fabrics within your home including carpets, window treatments, and furniture.
Is Low-E glass worth it?
Quality Low-E glass does help block out UV and IR rays, giving your home a wide range of benefits. Blocking UV light can help reduce the wear and tear on fabrics and other materials in direct sunlight. Blocking IR light can help improve the efficiency of heating and cooling your home, by controlling the passage of heat in and out of windows.
There are other solutions that can block heat and UV similarly - standard thermal films, thermal curtains and blinds, etc. But unlike most of these, Low-E glass allows you to maintain a clear view with plenty of natural, visible light entering your home. You don’t have to sacrifice access to the sun to get rid of its downsides if you install Low-E glass.
It’s important to realize the insulation of Low-E glass applies to all forms of heat, not just the incoming IR of the sun. That means that during the winter, it helps trap heat inside your home, keeping you more comfortable.
How to clean Low-E glass
If you've done much research on Low-E, you may have read that it can require special care. While this is true, special care is not required often. The majority of insulating glass has Low-E coatings between multiple panes of glass, instead of being exposed to the surface, meaning that it will not require cleaning. In other cases where the Low-E coating is exposed and will need to be cleaned, you may need to avoid using ammonia-based cleaners, abrasive cleaning instruments (such as squeegees), and instead need to use a lint-free cloth or microfiber cloth with a basic ammonia-free window cleaner. Be sure to read your manufacturer's suggested care instructions for proper cleaning.
Exploring your options
There are a variety of options within the confines of Low-E glass, so look for the proper fit for your home, climate, and budget. Consider window energy ratings to help evaluate the options and find a product truly suitable for your home. If you have questions or want more information, visit your local Pella Showroom. There you will find information on the