Your home’s windows can be a major source of heat loss in winter and can absorb heat from sunlight during the warmer months. While using shades and drapes can help cut down on heat transfer from your windows, there are times when you want to pull them open and let the light in. When you do, there’s a type of window and coating that can prevent heat transfer through your windows without obstructing the view: Low-E windows.
What are Low-E windows?
Low-E windows are made from glass that has a microscopic metallic coating on it that is barely visible. You likely won’t notice the coating because it doesn’t change the way your windows look very much, but it insulates windows from heat transfer by reflecting UV and infrared light. Low-E coating narrows the wavelength of light that can come through your windows, cutting down on the wavelengths of light that transfer the most heat through the glass. By preventing heat from being absorbed through the windows, Low-E glass can keep the inside of your home cooler in summer and warmer in winter.
Windows with a Low-E coating can reduce heat transfer by 70%. That means that one of the biggest sources of energy expenditure on temperature control can be reduced by 70% with a low e coating. Low-E windows can save you 12% to 33% on energy by providing reflective insulation. Depending on where you live, this can amount to an annual saving of between $70 and $500. While the initial investment in Low-E windows can be 10% to 15% more than regular windows, the savings can be worth it if you live in an area with higher energy costs or where your HVAC is running year round.
Since Low-E coatings reflect UV light, having Low-E windows can prevent sun damage to carpets, artwork, and furniture. Cutting down on UV light can also help prevent bleaching on hardwood floors and woodwork. Some types of plastic can also be damaged by UV rays, so adding a Low-E coating can save you money on replacing or repairing furniture, flooring, and textiles by preventing that damage.
DIY Low-E coating versus new windows
Low-E windows can either come pre-coated from the manufacturer, or an e coating film can be applied on site by a homeowner. The DIY type of window film can be time consuming, and as with any window film, it can be tricky to get right. The upside to the DIY approach is that you can apply it to your existing windows for around $1.44/square foot or around $9 per window. The DIY type of Low-E window coating will last about 10 to 15 years if properly installed. While new windows with Low-E coating on them are significantly more expensive than the film, if you have older windows, they can be worth it for sealing up leaks and gaps that the film won’t fix.
Unlike other types of spectrally selective window coatings that can frost or tint windows, Low-E windows don’t need to have a visible tint. While in some cases, there can be a very slight tint, for the most part, the coating is invisible. That means you can have all the benefits of natural sunlight, plus a clear view while still keeping heat transfer to a minimum and reducing your home energy bill.