FAQs
Everything you need to know about Low-E glass windows
If you can feel the heat of the sun shining through the windows in your home, that’s the effect of ultraviolet (UV) rays transferring through the glass. While additional warmth might feel great in the winter, it’s not ideal on a hot summer day.
Also, if despite having your furnace running constantly when colder weather arrives you still feel a chill, it might be a result of heat loss through the glass in your outdated windows.
Keep reading to get the facts on low-emissivity (Low-E) glass windows, learn about their benefits, and decide what level of Low-E coating is right for your home.
%3Afill(transparent)&w=2000&q=75)
Key points
Low-emissivity (Low-E) glass windows can keep your house cool in the summer and warm in the winter — potentially lowering your monthly energy costs
Pros and cons of Low-E glass in your home
The right level of Low-E glass in your home depends on your climate, budget, and the direction your home is facing
What is Low-E glass and how does it work?
When comparing Low-E glass versus regular clear glass windows, the difference is in how much heat is allowed through the panes. Glass alone will not reduce the effects of radiant heat transfer, but window options like Low-E coatings can.
Low-E glass has a microscopic coating that is applied to the exterior or both sides of the window. The Low-E levels are named according to how many coats are used.
Low E1 is the lowest glazing option and features one layer of coating. This option is ideal for homes in colder climates with direct sun exposure.
Low E2 features two layers of coating that reflect heat that contacts the window surface and is best used for homes in moderate climates.
With three layers of coating, Low E3 does a better job at blocking solar heat while still letting desirable sunlight into your home. This glazing option is appreciated in climates with year-round intense sun exposure.
Offering the highest level of protection is Low ERS, which has a coating on the interior side of the glass and is paired with either Low E2 or Low E3 on the exterior. The interior coating reflects heat back into the room to ensure maximum energy efficiency in every season.
%3Afill(transparent)&w=2000&q=75)
%3Afill(transparent)&w=2000&q=75)
How Low-E windows can contribute to lower energy bills
Upgrading from single-pane to double-pane or triple-pane windows will improve their energy efficiency but adding Low-E coatings is the key to truly optimizing your home. The main way Low-E windows help keep monthly bills low is by preventing heat loss and gain through the glass.
Having a Low-E3 coating on a window can improve energy efficiency by up to 70%. Its thin, metallic layer reflects UV rays and blocks excess solar heat, helping keep your home cooler during the summer months and reducing your reliance on air conditioning. This can translate to energy savings of up to 13% on your monthly energy bills, according to ENERGY STAR savings estimates.1
The pros and cons of Low-E glass
Pros of Low-E glass
Protecting your furniture and belongings
Furniture, flooring, and upholstery can fade over time due to damaging UV rays that easily pass through single-pane window glass. Low-E glass can help limit UV exposure while still letting natural light in, preserving the longevity of your valued belongings.
Increased comfort
Since Low-E coatings prevent the transfer of heat through windows, your indoor temperature will remain more consistent during warmer months. It also means that you can sit in your favorite cozy chair and read a book while staying cool.
Lower energy bills
You'll waste less energy and can save more money each month when your air conditioning runs less often, thanks to the protection from UV rays that Low-E glass provides.
Resale value
Another big reason why energy-efficient windows with Low-E coatings are a smart investment is that they can help boost your home’s resale value. As a result, you can often recoup some of the investment you made in your windows when it's time to sell.
Cons of Low-E glass
Cost
Selecting Low-E glass upgrades can result in a higher upfront cost for windows, but the improved comfort and lower energy bills might be worth the investment.
Slight tint to the glass
Low-E glass coatings are less than paper thin, so you might not notice that there is a subtle tint to the surface.
Dims daylight
Even though the difference is minimal, the tinting used in Low-E glass reduces the amount of daylight that enters through the window.
Condensation
Because Low-E glass does such a good job of reflecting heat, condensation might form on the surface because the window doesn’t get hot enough for the moisture to evaporate.
What Low-E glass level is the right choice for your home?
Low-E coatings aren’t a one-size-fits-all solution for every home. The right choice depends on your climate, personal preferences, your budget, and the direction your home is facing.
Most premium windows today come standard with a Low-E coating to meet current ENERGY STAR version 7.0 guidelines, while your home’s location might require an upgrade to a Low-E2 window coating or higher.
For example, if you live in a climate that experiences extreme heat, it might make sense to invest in a Low-E3 coating. Alternatively, if your winters are long and cold, a Low-ERS glazing option on windows and patio doors would help keep your home cozier by reflecting internal heat back towards the room.
Where your house sits on your lot also makes a difference when it comes to which windows receive the most direct sunlight.
You might choose to invest in a Low-E2 or Low-E3 coating for south- or west-facing windows where it will have the most impact, while selecting Low-E1 for the rest of the home. It’s a logical and budget‑friendly strategy, given that higher coating levels cost more.
Your personal comfort might be the most important factor when it comes to which type of Low-E coating you choose. While reducing the amount of heat lost through your windows will save money on energy bills, having a consistent temperature in your home is something you can’t put a price on.
Thinking about a window or patio door upgrade, but you’re not sure where to start? Get a free, no-pressure consultation from an Infinity consultant in your community.
1 ENERGY STAR at energystar.gov. Savings estimates are based on EnergyPlus 9.5 modeling for typical homes in 132 U.S. cities. Ranges are based on the average savings among homes in modeled cities. Actual savings will vary based on local climate conditions, utility rates, and individual home characteristics.