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Written By Ryan Merchant
The days are getting longer, and the temperatures are creeping up. It will be time to turn on the AC before we know it.
Now is a great time to assess the efficiency of your windows in maintaining a comfortable indoor temperature. Drafty windows, thin glass, and insufficient window treatments make it easier for the stifling summer heat to find its way into your home, making your AC work that much harder and increasing your energy bill. In fact, the Department of Energy estimates that windows account for 25-30% of residential heating and cooling energy use.
You can insulate windows for summer in multiple ways. Some methods are more effective—and expensive than others. Let’s review the most common insulation options so you can pick the treatments that work for you.
You can insulate windows for summer in multiple ways. Some methods are more effective—and expensive—than others. In this comprehensive guide, we'll review the most common insulation options so you can pick the treatments that work for you, helping you stay cool while reducing your energy costs.
Here’s how to insulate windows to keep your home cool through the summer. These six solutions are roughly ordered from least expensive to most expensive. Bear in mind that the best window insulation for summer entails a combination of the options described below.
If your windows have an imperfect seal, a draft snake or stop is a quick, inexpensive solution. A draft snake is just a few dollars, and it’s readily available online and in hardware and home goods stores. There’s no installation to speak of. Simply wedge the snake where the window sash meets the sill.
Draft snakes have their uses, but they can be a bit bulky to place on a window. They also do nothing to prevent drafts that might come from the top or sides of a window’s framing.
DIY Draft Snake Option: You can make your own draft snake by filling a tube sock with rice, dried beans, or even sand, and then sewing or tying the open end shut. This homemade solution costs next to nothing and works just as well as store-bought options.
Just like a draft snake, weather stripping can limit the exchange of air through a drafty window. Weather stripping is a little less conspicuous, though, and you can apply it to the entire perimeter of a window.
Weather stripping is inexpensive and easy to apply. Simply measure an appropriate length of stripping, peel back the covering to expose the adhesive, and apply firmly to your window framing. You can remove weather stripping whenever you like, so it’s a great way to insulate apartment windows.
Types of Weather Stripping for Windows:
Draft snakes and weather stripping won’t stop the hot summer sun from warming your home. If your windows get a lot of sun, you can apply a thin film to reflect sunlight. Some inexpensive film is made for any homeowner to install. Other kinds of higher-grade film must be installed by a professional.
Reflective film is good at keeping a home cool in the summer, but some homeowners don’t find it to be aesthetically pleasing. For this reason, reflective film is sometimes more common on office buildings and storefronts.
Blackout curtains are made of thick fabric that is especially effective in blocking light and, by extension, heat. Think of the curtains you might see in a hotel room.
Blackout curtains tend to be heavy, so they might require stronger mounting brackets, but they are otherwise no harder to install than any other kind of curtain. Some people find blackout curtains to be a little too effective, however. They can completely darken a room in the middle of the day, which some people find disorienting. You might want to mitigate the heat from the summer sun, but not at the expense of losing all the natural light in your home.
Cellular, honeycomb, and solar blinds are elegant, attractive, and can trap or reflect the sun’s heat while still allowing some ambient light to pass through. They’re a wonderful way of keeping your home cool and comfortable, but quality blinds can be expensive. The costs add up when you consider professional installation.
Finally, you can make your home more energy efficient by replacing your windows entirely. Thermal, double-paned, or heat-proof windows are more than twice as effective as standard glass when it comes to keeping your home cool in the summer and warm in the winter. Most models use two panes of glass with insulating argon gas sealed between them.
The downside is that replacing your windows is quite expensive. The argon between the panes escapes slowly over time, too, so you may need to replace these windows again in about 20 years.
Beyond the six methods mentioned above, here are some additional techniques to consider for summer window insulation:
Exterior solutions prevent heat from reaching the glass in the first place, making them more effective than interior options. Awnings can reduce solar heat gain by up to 65% on south-facing windows and 77% on west-facing windows.
Types of Exterior Window Coverings:
Natural shade is an eco-friendly way to keep your windows cool. Deciduous trees are ideal because they provide shade in summer but allow sunlight through in winter when they lose their leaves.
Before adding any window treatments, make sure your windows are properly sealed. Caulking is an inexpensive way to seal small cracks around window frames.
How to Apply Caulk Effectively:
For rarely-used windows or temporary insulation, bubble wrap provides surprisingly effective insulation. This method is especially useful for basement or utility room windows.
Window inserts are custom-built acrylic or glass panels that create an additional insulating air space inside your existing windows. They're less expensive than replacement windows but offer significant energy savings.
Benefits of Window Inserts:
When deciding how to insulate your windows for summer, consider these factors:
Insulation Method | DIY Cost per Window | Professional Installation | Longevity |
Draft snake | $5-15 | Not needed | 1-2 years |
Weather stripping | $10-20 | Not needed | 2-5 years |
Reflective film | $25-100 | $200-400 | 5-10 years |
Blackout curtains | $40-200 | Not needed | 3-7 years |
Cellular blinds | $50-200 | $50-100 per window | 7-10 years |
Window replacement | $300-1,000 | Included in price | 15-30 years |
Exterior awnings | $200-3,500 | $200-500 | 5-15 years |
Window inserts | $100-300 | Often included | 10+ years |
Insulation Method | Heat Reduction | Light Control | Air Leakage Prevention | Visual Appeal |
Draft snake | Low | None | Moderate | Low |
Weather stripping | Low | None | High | High (not visible) |
Reflective film | High | Moderate | None | Moderate |
Blackout curtains | High | High | Low | High |
Cellular blinds | Moderate-High | Adjustable | Low | High |
Window replacement | Very High | Varies | Very High | High |
Exterior awnings | Very High | Moderate | None | High |
Window inserts | High | Low | Very High | Moderate |
If you're renting and need non-permanent solutions:
For the best results, consider combining multiple insulation methods:
Different seasons require different approaches to window insulation. Here's a year-round strategy:
After implementing window insulation methods, monitor their effectiveness:
There's a reason Liberty Home Guard was rated the #1 Home Warranty Service by U.S. News and World Report for 2021, 2022, 2023, and 2024. Check out our services.
Learn MoreProperly insulating your windows for summer is one of the most effective ways to improve your home's energy efficiency and comfort during hot weather. By implementing some of the strategies outlined in this guide—whether simple DIY solutions like weather stripping and window film or more substantial investments like high-efficiency window replacements—you can significantly reduce your cooling costs while creating a more comfortable living environment.
For comprehensive protection of your home's cooling system during the hot summer months, consider supplementing your window insulation efforts with a home warranty from Liberty Home Guard. Our plans provide peace of mind and financial protection against unexpected AC breakdowns when you need cooling the most.
According to the U.S. Department of Energy, properly insulating windows can reduce cooling costs by 25-30%. For the average American household spending $300-400 on summer cooling, that's a potential savings of $75-120 per season. The exact savings depend on your local climate, existing window efficiency, and the insulation methods you choose.
Focus on south and west-facing windows first, as they receive the most direct sunlight and heat during summer months. Large picture windows and windows in rooms that feel particularly hot during the day should also be priorities. If you can't insulate all windows at once, addressing these high-impact areas will give you the best return on investment.
Yes, quality reflective window films can reduce heat gain by 70-80% on sun-facing windows. These films work by reflecting solar radiation before it can enter your home. While they're not as effective as exterior shading or high-efficiency replacement windows, they offer one of the best cost-to-performance ratios for summer window insulation, especially for renters who need non-permanent solutions.
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Absolutely. Several options provide good insulation while maintaining visibility:
When insulating windows for summer, you'll often encounter these two measurements:
U-factor is the inverse of R-value (U = 1/R). While a single-pane window typically has an R-value of 0.9, double-pane windows range from 2.0-3.3, and triple-pane windows can reach R-5.0 or higher. When shopping for energy-efficient windows, look for a low U-factor (ideally below 0.30) for better summer performance.
Many utilities and government programs offer incentives for energy-efficient home improvements, including window insulation. Check with your local utility company for rebate programs on window treatments or replacements. The federal government periodically offers tax credits for energy-efficient home improvements through programs like the Energy Efficient Home Improvement Credit. Local and state governments may offer additional incentives.
Historic windows require special consideration:
These methods provide insulation without permanently altering historically significant windows.
Yes, strategic landscaping can significantly reduce heat gain through windows. Deciduous trees planted on the south and west sides of your home can block 70-90% of summer sun while allowing winter sunlight through after leaves fall. Fast-growing vines on trellises can provide quicker results while waiting for trees to mature. Even potted plants on exterior windowsills can create cooling microenvironments that reduce heat transfer.
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