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It may come as no surprise that heating-related costs make up the majority of monthly energy expenses for most U.S. households. For many homes, windows bear at least some of the blame for sky-high energy bills, drafty days, and layered sweaters.

Just how much heat is gained and lost through these portals, exactly? Anywhere from 25% to 30% of your home’s overall heating and cooling energy use on average. But simple improvements can make a world of difference, and not just in terms of comfort and energy costs. Done right, it can help fast-track the timeline from initial investment to increased home resale value of 5% or more, too.

Bearing all of that in mind, there are basically two approaches to winter window sealing:

  • Going the lower-cost DIY route

  • Investing in material upgrades and getting professional help

We’ll detail best practices for both below, but as you’ll see, they aren’t mutually exclusive — the appropriate initial step is the same either way. And for homeowners interested in taking performance measures into their own hands, it might make the most sense to start with simple DIY fixes, see how far that takes you, then decide whether or not to level-up the investment from there.

Arrange a Home Energy Audit

For any homeowner who wants their dwelling to be safe, healthy, comfortable, and energy efficient, arranging to have a home energy audit carried out by a licensed professional is the essential first step.

Why? Because these energy assessment professionals bring to the equation not just specialized training, knowledge, and expertise, but also an arsenal of tools you won’t be able to replicate through any amount of DIY ingenuity. Think: infrared cameras to monitor the movement of heat through your home’s walls, high-powered fans to depressurize your home as part of the all-important blower-door test, and so on.

As a result, the energy audit will help you get to the bottom of more than window-related air leaks. Ultimately, the audit should provide you with a comprehensive overview of where your home stands in terms of energy efficiency, which should make prioritizing upgrades — and investing in the right ones — a whole lot easier going forward.

Of course, if you’re really committed to winter-sealing your windows without bringing in outside assistance, there are a couple of DIY workarounds that might be effective — but no promises. One is to buy several sticks of incense, set them up in various rooms in your house, then study the direction in which the smoke drifts — in theory, it might help you locate sealing gaps in or around windows. Another, slightly more reliable solution is to purchase a bonafide temperature sensor and use it to validate if and where cold pockets exist near windows.

Related Post: What's a Home Energy Audit and When Do I Need One?

The DIY Route: 5 Relatively Quick and Low-Cost Fixes

If heat is found to be leaking through minor gaps or spaces in or around your home’s windows, then plugging them, in one way or another, is going to be your first line of defense, obviously — and your best bet will almost certainly be one of the following five options.

1. Remove the Trim

This step only applies if the exterior or interior window trim can be removed. Remove the trim. Inspect the insulation between the window frame and the window opening. If there are obvious gaps, fill those gaps with either proper foam insulation or with loosely-packed fiberglass insulation.

2. Caulk

Window caulking is a straightforward, relatively inexpensive and reliably effective fix for most homeowners. Just take the following two-step approach:

  • First, going outside, caulk around the exterior perimeter of the windows in question.

  • Next, moving inside, caulk any gaps or cracks that you find between the window “casements,” or their interior trim, and the wall, as this is typically where heat escapes. A clear caulk may create a more visually appealing finish between the window trim and the wall surface.

Finally, in the event you don’t plan to open the window for the duration of the winter, which isn’t altogether unusual in colder climates, it might be best to simply caulk around the entire window, creating a comprehensive shield to prevent heat loss. Just be sure to use a removable caulk, such as rope caulk, if you do so. And avoid caulking the entire window if it’s a point of egress, like a bedroom window.

3. Window Film

The goal of window film — like most of these solutions — is to construct a thin, yet insulating, barrier capable of finally closing any gaps that exist between the window and your home’s interior. Inexpensive, available at most hardware stores, and usually sold as a kit, window film can be affixed to your windows in various ways — some are interior-only and some are exterior-only. Some kits rely on double-sided tape alone, for example, while others will need to be lightly heated with a hair dryer.

4. Bubble Wrap

Not just a packaging solution, bubble wrap can add a valuable layer of thermal insulation to interior windows, but note that this is mostly helpful when the windowpane — the glass itself — is the issue. Of course, you won’t be able to see out your window if you use this method. Here are the steps:

  • Measure the window and cut the bubble wrap to size (a guillotine trimmer can be used).

  • Thoroughly clean the window, as well as the window frame, and let them dry.

  • Spritz some water on the inside of the windowpane, then press the bubble wrap (with the bubbles facing out) against the wet glass.

  • Hold the bubble wrap in place and seal its edges with tape. You should be careful about the type of tape you use, however — otherwise, when you remove the bubble wrap come spring, you might pull up any adjacent paint along with it.

5. Magnetic Window Insulation or Thermal Curtains

Both of these solutions have one “working” advantage over most of the others, which is that they’re very easy to put up and take down once they’ve been properly installed. On the other hand, installation itself isn’t going to be seamless, with tools and assembly required. Anecdotally, you’ll probably have to spend around $100, minimum, for either of these options, and in all likelihood you’ll need to go to a large retail hardware store in order to shop for them.

Related Post: Second Step to a High-Performing Home: Air Sealing

The Professional Route: Investing in Upgrades

If the energy audit has found that you’re spending more than you should on heating costs due to window-related heat loss, then you might want to invest in a wholesale upgrade. In fact, swapping out heat-leaking windows for more energy-efficient alternatives makes bottom-line sense in most cases.

For one, homes featuring ENERGY STAR®-rated windows have been shown to have 7%-15% lower annual energy costs compared to those with traditional windows in general, depending on the location and type of window being replaced. In fact, when combined with saved energy costs, these upgrades frequently pay for themselves, reliably delivering ROI between 60% and 70% on the resale market at time of sale. On top of that, you can take advantage of tax credits on these and other performance-related projects right now through the Inflation Reduction Act (IRA) of 2022.

Related Post: The Green Door Guide to Energy-Efficient Window and Door Rebates and Tax Credits

In the meantime, if you’re still at the consideration stage, a qualified contractor should be able to advise you on the best windows to invest in based on the findings of your home energy audit. Sign up or login to Pearl’s free Green Door app to locate a vetted contractor near you. You can also use this Window Selection Tool from the National Fenestration Rating Council (NFRC) as a way to prep for your conversation with your contractor. (Fun fact: Pearl’s own senior sustainability analyst Kerry Harp designed the original version of this tool!)

Related Post: Pearl’s Guide to Energy-Efficient Windows

Next Steps

There’s no good reason to suffer through the interminable months of winter huddled around radiators or cocooned in layered sweaters. After all, you can measurably improve your home’s energy efficiency during the cold season by following the simple window-sealing best practices outlined above. What’s more, you should expect to recoup your investment at time of sale and to capture additional savings thanks to the IRA. 

Ultimately, regardless of the approach you decide to take, downloading Green Door, the free app from Pearl Certification, can make these projects easier to plan and execute. You’ll find it comes with all the tools and resources you need to approach home performance improvements with far greater confidence. For instance, you might use the app to connect with qualified contractors and real estate professionals in your area, certify your investments (a requirement in order to take advantage of certain IRA rebates) — and a whole lot more.

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