What Are Low-E Windows?

Your home’s windows are a critical-but-overlooked part of your home’s energy efficiency and, therefore, your utility bills. Windows provide natural light and views, but they may be a major source of heat loss in the winter and heat gain in the summer. 

Low-E windows could be a solution to lowering those bills, giving you more comfort, and saving energy. This guide explores the benefits of energy-efficient windows, particularly those with low-emissivity coatings, film, or tint, and offers other ideas to help you save energy and money year round.

What Are Low-E Windows?

Low-E is short for low emissivity. Heat naturally wants to move from a warmer area to a cooler area. When it’s cold outside, it’s warmer in your house and heat will escape through a window. When it’s hot out, the heat outside will naturally radiate or pass through a window into your home. 

A low-E window is a double- or triple-pane window and has a thin coating you can’t see, unless it is tinted, on one pane that slows the passage of heat in both directions, so it saves you energy and money year around. 

What Are the Benefits of Low-E Windows?

The primary benefits with low-E windows are better energy efficiency and savings for your home heating and cooling. More heat stays in your home in winter and more heat stays out in summer. Here are other positives to consider.

• Lower energy bills: Low-E windows let your HVAC system run less whether it’s heating or cooling. A range of commercial sites give a range of estimated annual savings of $27-$500. Savings depend on factors such as climate, energy rates, number of windows replaced, and the condition of the old windows (you’re likely to save more if you’re replacing older or single-pane windows).
• UV radiation protection: The low-E coating blocks most UV radiation which stops ambient heat as well as wear and damage to floors and furniture. 
• Natural light: While there are tinted options, non-tinted low-E windows give you the benefits of energy efficiency while still letting natural light in so you have the health benefits, aesthetics, and further energy savings of letting sunlight into your home.

Does Low-E Window Film or Tint Work?

There are window film and window tint products which can give you some of the same benefits as low-E windows while being more budget-friendly. 

Low-E film goes on the interior of a window pane and is primarily used to keep heat in or out and keep UV rays out. Drawbacks of using film are the product won’t have the likely lifespan or durability of new windows, or the air sealing effect of new windows, so heat/energy may still be lost in drafts or older windows or frames. Adding film may void a warranty if you have one on your windows.

Low-E tint decreases the solar energy and visible light passing through a window. So, in summer, tint reduces heat gain inside. Using only tint, but no low-E pane or film, makes a much smaller difference in heat loss during cooler weather and seasons.

Windows and Energy Efficiency

Installing new low-E windows or using film or tint to control heat loss or gain are good steps to greater energy efficiency and comfort in your home. There are other tips and projects you can do to make your windows part of saving energy and saving money year around. 

Data from the US Department of Energy shows 25-30% of heat gain or loss in an average house happens through the windows.

Shy of replacing your home’s windows, energy-saving tasks can include checking and adding caulk and weatherstripping along windows. Adding or remembering to use curtains or blinds can create shade and an extra layer of insulation when needed. Even outside around your windows and home, using awnings or planting trees and shrubs to create natural shade and windbreaks can moderate temperatures and take some of the load off your heating and cooling system. A home energy audit can check insulation levels, window sealing, and temperature differences between rooms or floors, or near windows and doors, to show you more ways to save.

If you’re looking at more ways to save energy or move toward home electrification, get actionable ideas and customized estimates with Palmetto’s savings maximizer tool.

Frequently Asked Questions

What are low-E windows?

Low-E windows have coated window panes to keep heat inside when it’s warmer inside than out, and heat outside when it’s warmer outside than in. Low-E windows may be an energy-efficient addition to your home plus give you more comfortable and consistent temperatures. 

Is low-E window film worth it?

Low-E window film can give you some of the same temperature control and energy efficiency as low-E window panes, but without the larger expense of new windows. They are generally not as effective as low-E windows.

How do windows affect a home’s energy efficiency?

Windows and window frames can be a major point of heat loss or gain in a home and heating and cooling is a major source of energy usage in most homes. Old, poorly-sealed, or single-pane windows can be drafty, leaky, and allow energy loss you wind up paying for.