How Low-E Film Can Benefit Your Home and Wallet

I love stepping into my house after a long day and finding a warm, inviting space. What’s my secret? It’s not just about tasteful interior design or the mismatched, well-worn, but much-loved furnishings.

My windows are covered with low-E film. It’s a simple solution that makes my home more energy efficient and helps regulate internal temperature all year round.

What Is Low-E Film?

Low-E, or low-emissivity, film is a thin coating applied to window surfaces to reduce heat transfer. It is a sustainability technique that modern day sustainable builders incorporate in their work for a sustainable environment.

The film features microscopic layers of metal or metallic oxide, reflecting heat while still allowing light to pass through. The result? A more comfortable, energy-efficient home environment, with all the natural light you love.

Low-E film pros

• Energy efficiency: By reflecting heat back to its source, low-E film can drastically reduce your energy costs. It keeps your home cooler in the summer by reflecting sunlight and heat outside, and warmer in the winter by reflecting heat back inside.
• Comfort: It helps maintain a consistent, comfortable temperature throughout your home, minimizing hot and cold spots. I have several large windows in my kitchen. In the summer, the room was unbearably hot unless I closed all the drapes and put the air conditioning on full blast. And the same room was bitterly cold in the winter. But with the low-E film in place, the kitchen feels much cozier year-round, apart from on the very hottest and coldest days.
• UV protection: Low-E film blocks up to 99% of the sun’s harmful UV rays, protecting your skin and preventing furnishings and flooring from fading.
• Versatility: It can be applied to existing windows, offering a less expensive and disruptive option than full window replacement.

Low-E film cons

• Cost: While less expensive than full window replacements, the initial cost might still be higher than other window treatment options.
• Aesthetics: Some people may not like the slightly shiny appearance of low-E film, which can change the look of your windows.
• Professional installation: In the U.S., it’s hard to find direct-to-consumer low-E film to self-install. Pro installation adds to the cost.

Low-E Film vs. Window Insulation

Low-E film and window insulation aim to improve energy efficiency. But they function in different ways, and each has its own advantages.

Window insulation works by creating an airtight seal, reducing drafts and preventing cold air from entering or warm air from escaping. Installing window insulation works best for homes with older, drafty windows, and it’s pretty easy and cost-effective to do yourself — about $2 to $3 per window.

Low-E film, on the other hand, focuses on controlling radiant heat transfer. It’s particularly effective in homes in hot climates or with large, sun-facing windows.

While it doesn’t prevent drafts like window insulation does, it’s less intrusive and can offer significant energy savings. However, because film isn’t typically available to DIY in the U.S., it costs between $4 and $19 per square foot for materials and labor.

Your choice will depend on your home’s specific needs.

Low-E Window Film Installation

While there are many types of DIY window film available to consumers in the U.S., we couldn’t confirm a source for low-E window film sold to consumers for DIY installation. If you buy window film to install yourself, be sure you understand its intended purpose.

I live in the United Kingdom, where DIY low-E film is readily available. I found self-installation a manageable project, although it requires precision to fit correctly, without creases or bubbles. Remember, too, that it goes on the inside of your windows.

Here’s a general how-to:

1. Measure your window: Accurate measurements are key to getting the right fit.
2. Clean your window: Any dirt or dust can interfere with the film’s adhesion.
3. Cut the film: Roll out your film and cut it slightly larger than your window.
4. Apply the film: Spray the window with a wetting solution, remove the backing and apply the film to the glass.
5. Smooth out bubbles: Use a squeegee to remove any bubbles, working from the center outward.
6. Trim excess film: With a sharp knife, carefully trim the edges for a perfect fit.
7. Wait: Check the manufacturer’s directions to see how long you need to wait for the film to fully adhere before you start using the window again.

Low-E Window Film Maintenance

Maintaining your low-E film is straightforward. Cleaning can be done with standard glass cleaning products and a soft cloth or squeegee.

Avoid any abrasive materials that could scratch the film. I use a simple 50/50 white vinegar and water spray and a microfiber cloth.

Maximizing the Energy Efficiency of Your Windows

There’s not much point in installing low-E film if you’ve got drafty frames and other heat transfer problems. Since you’re already giving your windows a thorough cleaning to install the film, you may as well take advantage and do some other window winterizing tasks.

Start with checking the seals around the frame, inside and out. If the caulk is old, degraded or damaged in any way, it’s a really good idea to remove the old stuff and re-caulk your windows, inside and out.

Next, check the exterior of your windows and, if you don’t have it already, add weather stripping. If you do and it’s damaged, replace it. And consider installing storm windows to add an extra layer of protection during the winter months.