Insulate Your Home Windows for the Summer
Liberty Home Guard

Expert-Reviewed Content: Guided by Editorial Standards

Ryan Merchant

Written By Ryan Merchant

Published 05/12/25
Home Maintenance

Different Ways to Insulate Your Home Windows for the Summer

Key Takeaways:

  • Window insulation can significantly reduce energy costs – Windows account for 25–30% of residential heating and cooling energy use, so proper insulation can improve comfort and lower utility bills.
  • There are insulation options for every budget and living situation – From low-cost DIY fixes like draft snakes and weather stripping to long-term investments like cellular blinds and window replacements, homeowners and renters alike can find suitable solutions.
  • Combining methods is most effective – Using a mix of air-sealing techniques (e.g., caulk, weather stripping),solar heat-blocking treatments (e.g., reflective film, blackout curtains),and exterior shading (e.g., awnings or trees) provides the best results.
  • Monitoring effectiveness is crucial – Simple methods like temperature tests or energy bill tracking can help confirm whether your insulation efforts are working and identify areas needing improvement.

Why You Need to Insulate Windows for Summer

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.

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How to Insulate Windows to Keep Heat Out

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.

1. Use a draft snake.

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.

2. Apply weather stripping.

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:

  • V-strip/tension seal: These plastic or metal strips spring open to seal the gap between the sash and the frame
  • Felt: Inexpensive but less durable, felt strips work well for windows that aren't opened frequently
  • Foam tape: Self-adhesive foam is easy to install and effective for sealing smaller gaps
  • Rubber gaskets: More durable option for windows that are opened regularly
  • Silicone caulk: For permanent sealing of non-moving parts of windows

3. Apply reflective window film.

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.

4. Hang blackout curtains.

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.

5. Install cellular, honeycomb, or solar blinds.

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.

6. Replace your windows.

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.

Additional Ways to Insulate Windows for Summer

Beyond the six methods mentioned above, here are some additional techniques to consider for summer window insulation:

7. Install exterior window shades or awnings.

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:

  • Fixed awnings: Permanent structures that provide consistent shade
  • Retractable awnings: Can be opened or closed as needed
  • Exterior roller shades: Mount outside the window and can be raised or lowered
  • Bahama shutters: Hinged at the top and prop open at an angle
  • Solar screens: Fine mesh screens that block UV rays while maintaining visibility

8. Plant shade trees or install trellises.

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.

9. Apply caulk to seal cracks and gaps.

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:

  1. Remove old caulk and clean the area thoroughly
  2. Cut the caulk tube nozzle at a 45-degree angle
  3. Apply a continuous bead of caulk to all joints and seams
  4. Smooth the caulk with a wet finger or caulk smoothing tool
  5. Allow to dry completely before painting (if necessary)

10. Use bubble wrap for a quick, temporary solution.

For rarely-used windows or temporary insulation, bubble wrap provides surprisingly effective insulation. This method is especially useful for basement or utility room windows.

11. Install window inserts or interior storm 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:

  • Install without any permanent modifications to your home
  • Can be removed seasonally if desired
  • Reduce noise transmission
  • Improve insulation without changing the exterior appearance
  • Typical cost: $100-$300 per window (much less than replacement)

Evaluating Which Window Insulation Method Is Right for Your Home

When deciding how to insulate your windows for summer, consider these factors:

Cost Considerations

 

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

 

Effectiveness Comparison

 

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

Rental-Friendly Options

If you're renting and need non-permanent solutions:

  • Draft snakes
  • Weather stripping (removable types)
  • Tension rod curtains
  • Removable window film
  • Portable window inserts
  • Free-standing outdoor umbrellas

Combining Methods for Maximum Effectiveness

For the best results, consider combining multiple insulation methods:

  1. Seal air leaks with weather stripping and caulk
  2. Apply reflective window film to reduce solar heat gain
  3. Add interior window treatments like cellular shades
  4. Use blackout curtains during peak heat hours
  5. Consider outdoor shading for south and west-facing windows

Seasonal Window Insulation Strategy

Different seasons require different approaches to window insulation. Here's a year-round strategy:

Summer Window Insulation (May-September)

  • Keep window coverings closed during the day, especially on sun-facing sides
  • Open windows and coverings in the evening when outside temperatures drop
  • Use reflective treatments to block solar heat
  • Install exterior shading where possible

Fall/Spring Transition Periods

  • Use adjustable window treatments to allow solar heat gain on cool days
  • Keep windows insulated on hot days
  • Remove and store seasonal treatments as needed
  • Check and repair weather stripping and caulking

Winter Window Insulation (November-March)

  • Allow sunlight in during the day to warm the home
  • Close insulating treatments at night to retain heat
  • Add plastic film insulation for additional protection
  • Use draft stoppers to prevent cold air infiltration

Measuring the Effectiveness of Your Window Insulation

After implementing window insulation methods, monitor their effectiveness:

Simple Testing Methods

  • Temperature test: Use a thermometer to measure the temperature near insulated vs. non-insulated windows
  • Candle test: Hold a lit candle near window edges (when not drafty outside) to detect air leaks
  • Thermal imaging: Use a smartphone thermal camera attachment to identify heat loss areas
  • Energy bill comparison: Track cooling costs before and after installation

Signs Your Window Insulation Is Working

  • Consistent indoor temperatures
  • Reduced need for air conditioning
  • Less noticeable temperature difference near windows
  • Decreased energy bills during peak cooling seasons  
     

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Creating a Cooler, More Efficient Home

Properly 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.

Frequently Asked Questions

  • How much can insulating my windows save on cooling costs?

    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.
     

  • Which windows should I prioritize insulating first?

    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.
     

  • Do window insulation films really work?

    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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  • Can I insulate windows without blocking the view?

    Absolutely. Several options provide good insulation while maintaining visibility:

    • Solar shades with 5-10% openness factor
    • Low-E window film (clear varieties)
    • Window inserts with clear acrylic or glass
    • Retractable exterior shades that can be adjusted based on sun position
    • Top-down/bottom-up cellular shades that allow partial coverage
  • What's the difference between R-value and U-factor when choosing windows?

    When insulating windows for summer, you'll often encounter these two measurements:

    • R-value measures resistance to heat flow (higher is better)
    • U-factor measures the rate of heat transfer (lower is better)

    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.

  • Are there any tax credits or rebates available for window insulation?

    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.
     

  • How do I insulate windows in a historic home without damaging them?

    Historic windows require special consideration:

    • Use removable interior storm windows or window inserts
    • Install custom interior shutters
    • Apply removable weather stripping that won't damage original wood
    • Use heavy drapes on decorative rods
    • Consider exterior awnings that complement the historic aesthetic
    • Choose traditional roller shades or roman shades with thermal backing

    These methods provide insulation without permanently altering historically significant windows.

  • Can plants really help insulate windows in summer?

    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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