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If you’re wondering does plastic on windows help in summer, the answer depends on the season. People generally add plastic to windows as a method of winter insulation. But when you’re on the hunt for relief from summer heat, you might think about wrapping your windows in plastic. After all, it can help create an extra barrier against cold air, reducing heat loss and improving energy efficiency.
In the summer, the opposite is true. Adding plastic to your windows will make your home feel hotter and trap heat inside the plastic.
What are the best windows to keep heat and cold out?
The best windows for blocking heat and cold use Low-E glass coatings paired with double or triple pane glass.
What is a window insulation kit and does it work?
A window insulation kit is a plastic film you tape over windows to block winter drafts. It’s not a good consideration for cooling your home in the summer.
The Short Answer: No, Plastic on Windows Does Not Help in Summer
Plastic on windows does not help in the summer. It will not keep you cool or lower your energy bills. This is not an approach you want to use during the dog days of summer here in New England!
3 Reasons Why Plastic Heats Up Your Home in Summer
Here’s the hard truth about using plastic on windows in summer: it doesn’t just fail to cool your home — it actively works against you. There are three key reasons why.
Plastic Film Acts Like a Greenhouse
Plastic film acts like a greenhouse on your windows. Here’s a breakdown of how it traps heat:
- Solar heat absorption: The plastic film absorbs a significant amount of the sun’s heat energy that would normally be reflected away by the glass.
- Heat trapping: The absorbed heat is then trapped inside the plastic layer, creating a warm microclimate between the plastic and the window glass.
Infrared radiation: The plastic film is often not designed to reflect infrared radiation (heat), which further contributes to the warming effect.
Plastic Blocks Cooling Airflow and Cross-Ventilation
Plastic on windows can impede airflow and stop your home from cooling down effectively. This is because:
- When you open a window, the plastic film creates a partial blockage, limiting the amount of fresh air that can enter your home.
- Cross-ventilation, which involves opening windows on opposite sides of a room, is a common cooling strategy. Plastic film on these windows can drastically reduce the effectiveness of this method.
- Even when windows are slightly open, a natural draft can help to circulate air and cool down a space. Plastic film can disrupt this natural process.
Plastic Traps Moisture and Causes Foggy Windows
Do you have foggy house windows in the summer? Part of the culprit might come from plastic on windows. Condensation can form on plastic-covered windows for several reasons:
- Moisture Barrier: Plastic acts as a barrier, trapping warm, moist air from your home between the plastic and the glass.
- Temperature Difference: The temperature difference between the warm indoor air and the colder outdoor temperature causes the moisture in the air to condense on the coldest surface, which is the window glass.
- Reduced Ventilation: The plastic film can impede airflow, preventing the moisture-laden air from escaping and being replaced with drier air.
Foggy windows in summer moisture buildup can lead to several problems:
- Mold and Mildew Growth: Constant moisture provides an ideal environment for mold and mildew to thrive.
- Damage to Window Frames: Prolonged exposure to moisture can damage the wood or paint on your window frames.
- Health Issues: Mold and mildew can cause respiratory problems and allergies.
If you’re already seeing condensation or moisture between your panes, that may be a separate issue worth addressing. Learn more about what to do when my windows are leaking water (foggy windows).
Does Plastic on Windows Help Keep Heat In?
Yes — but only in one direction, and it’s not the one you want in summer.
Plastic film works by trapping air between the plastic layer and the glass, slowing the movement of heat through the window. In winter, that’s useful. In summer, it means heat from the sun gets trapped inside rather than escaping back outside. The plastic doesn’t distinguish between heat you want to keep and heat you want to lose. Unfortunately, plastic holds heat inside in the worst way possible.
Does Bubble Wrap on Windows Help in Summer? (Spoiler: No — Here's Why)
Bubble wrap on windows does not help in summer. Like plastic film, it traps solar heat against the glass rather than reflecting it, making your home warmer, not cooler.
Homeowners sometimes try bubble wrap windows for summer comfort as a low-cost DIY fix. It’s understandable — bubble wrap is cheap, easy to apply, and does create an air gap. But that air gap works very differently depending on the season, and in summer it works against you.
How Bubble Wrap Differs from Plastic Window Film
Bubble wrap and plastic window film might seem similar, but they behave differently on glass.
Bubble Wrap vs Plastic Window Film: At a Glance
Standard plastic window film is thin and sits flush against the pane. Bubble wrap creates a larger air pocket between the plastic and the glass due to its raised bubble structure.
That air pocket sounds like insulation — and in a technical sense, it is. The problem is that insulation is a two-way street. The same air pocket that slows heat loss in winter also slows heat escape in summer.
Unlike professionally manufactured window films, bubble wrap has no Low-E coating. It cannot selectively reflect infrared radiation. It simply traps whatever is on its warm side. In summer, that means trapping the sun’s heat inside your home.
Why Bubble Wrap Makes Summer Heat Worse
Using bubble wrap on windows in summer creates the same greenhouse effect as plastic film — only the bubble structure makes it slightly worse. Here’s why:
- Greenhouse effect: The bubbles trap a warm air layer directly against the glass, raising the surface temperature of the window and radiating that heat into your room.
- Trapped infrared radiation: Without a Low-E coating, bubble wrap cannot reflect infrared heat back outside. Solar heat passes through the glass, gets absorbed, and has nowhere to go.
- No ventilation relief: Like plastic film, bubble wrap interferes with natural airflow when windows are cracked open, compounding the heat problem.
It’s worth noting that bubble wrap can provide marginal benefit in winter — the trapped air pocket does reduce some cold-air infiltration around drafty single-pane windows. But that same property is exactly what makes it counterproductive once temperatures rise.
What About Garbage Bags, Cellophane, and Cling Film?
If bubble wrap and plastic film don’t work, what about other household materials? Homeowners across New England try all kinds of DIY fixes when summer heat hits — black garbage bags, cellophane, cling wrap, and shrink-film kits. Here’s an honest look at each one.
Black Garbage Bags on Windows: A Word of Caution
Of all the materials on this list, black garbage bags on windows are the most likely to make your heat problem worse — not better. That’s because:
- Black is the least reflective color on the visible spectrum.
- It absorbs heat rather than deflecting it
- A black garbage bag applied to a sun-facing window will absorb solar energy all day and radiate it directly into your room.
Some homeowners use black bags to block light for blackout purposes, such as darkening a room for sleep, for example. That’s a reasonable short-term use. But if your goal is to reduce heat, black garbage bags on windows will work against you. The room may get darker, but it will also get hotter.
A Side Note on Cellophane and Cling Film: Thin Material, No Real Benefit
Cellophane and cling film are even thinner than standard plastic window film. This means they offer even less in the way of insulation — and none of the heat-reflecting properties that matter in summer. Neither material has a Low-E coating. Neither can reflect infrared radiation. Applied to a window in summer, they function as a very thin plastic barrier with no meaningful impact on heat gain or energy bills.
Cling film in particular has been marketed informally as a DIY insulation tactic. While it creates a negligible air gap, that gap is too thin to slow heat transfer in any meaningful way. In winter, the benefit is marginal at best. In summer, it provides nothing.
3M Window Insulator Kit: Honest Review
The 3M Window Insulator Kit is one of the most searched window insulation products online, and it’s a legitimate product — just not for summer use. The kit uses a clear shrink film that you apply to the interior window frame with double-sided tape, then shrink taut with a hair dryer. It creates a sealed air pocket between the film and the glass.
In winter, that sealed air pocket reduces cold-air infiltration around drafty or older windows, and it does so reasonably well for the price. It’s a fair short-term solution for single-pane windows or windows with failing seals in cold climates like Massachusetts, New Hampshire, and Maine.
In summer, however, the same sealed air pocket traps heat, just like other types of plastic we’ve talked about. Meanwhile, the 3M kit has no Low-E coating and no infrared-reflecting properties. It is a winter insulation product, and using it in summer will make your home warmer, not cooler.
What Actually Works: How to Block Summer Heat from Windows
Unlike plastic, which doesn’t help in summer, here’s what actually does. If you’re looking for the best way to insulate windows for summer — and genuinely keep heat out — these are the solutions that work.
Low-E Glass Cools Your Home with Ease
Low-E, short for ‘low-emissivity,’ refers to coatings applied to glass during manufacturing. Visible light passes through, while infrared heat is reflected back outside. This helps to keep your home cooler in the summer and warmer in the winter.
Insulated Glass Reduces Heat Transfer
This type of glass consists of two or more panes of glass separated by a gas-filled space. The gas, usually argon or krypton, acts as an insulator to reduce heat transfer.
Vinyl Window Frames Prevent Energy Loss
Window frame materials vinyl offer better insulation compared to traditional wood or aluminum frames. They can help reduce heat transfer through the window frame, keeping your home cool and your energy bills in check.
Custom Window Placement
Proper window placement can minimize solar heat gain. You’ll want to avoid large south-facing windows, which can directly impact the comfort levels in your home during the summer. By working with a window contractor, you can optimize your home’s energy efficiency with custom window replacement.
Solar Shades, Window Tint, and Cellular Blinds
For homeowners not yet ready for full window replacement, interior and exterior window treatments can provide a meaningful — if temporary — reduction in summer heat gain.
- Solar shades are roller shades made from an open-weave fabric that blocks a percentage of incoming solar radiation while still allowing some natural light through. They won’t eliminate heat gain, but they reduce it noticeably on south- and west-facing windows.
- Window tint film works by applying a thin metallic or ceramic layer to the glass surface. Unlike plain plastic film, quality window tint is specifically engineered to reflect infrared radiation — the part of sunlight that carries heat. It’s a meaningful upgrade over DIY plastic, though it still falls short of factory-applied Low-E glass.
- Cellular blinds (also called honeycomb shades) trap air in their honeycomb-shaped cells, creating a buffer zone between the glass and your interior. They’re more effective at reducing heat transfer than standard blinds and work in both summer and winter.
None of these treatments match the performance of purpose-built energy efficient replacement windows, but they can help bridge the gap while you plan a longer-term upgrade.
Comparison: What Actually Blocks Summer Heat?
Solution | Blocks Solar Heat | Reflects Infrared | Improves Airflow | Long-Term Fix |
Plastic film |
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Low-E glass |
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Window tint film |
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Solar shades |
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Cellular blinds |
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Does Plastic on Windows Help in Winter? (Yes — Here's Why)
Yes — plastic on windows does help in winter. This is the one season where the same properties that make plastic harmful in summer actually work in your favor. That said, it’s a temporary fix, not a permanent solution. If you’re relying on plastic film every winter, your windows are telling you something important.
In winter, plastic film creates an insulating air barrier between the film and the glass. That trapped air slows heat loss from your warm interior to the cold outdoors — which is exactly what you want when temperatures in Massachusetts, New Hampshire, and Maine drop below freezing. It won’t make an inefficient window perform like a modern double- or triple-pane replacement, but it can meaningfully reduce drafts and heat loss around older or single-pane windows for the season.
If you’re also noticing moisture buildup during the colder months, that’s a related but separate issue worth understanding. Learn more about condensation on windows in winter and what causes it.
Summer vs. Winter: When Plastic Helps and When It Hurts
The same property — trapping air — produces opposite results depending on the season. Here’s a simple side-by-side breakdown:
Summer | Winter | |
Does plastic on windows help? | ❌ No | ⚠️ Temporary results |
What the air gap does | Traps solar heat inside | May slow heat loss to outside |
Effect on temperature | Makes home hotter | May slow drafts and heat loss |
Effect on airflow | Blocks cooling ventilation | May reduce cold infiltration |
Effect on condensation | Increases moisture buildup | Can increase condensation risk |
Verdict | Remove it | Apply it carefully |
Best long-term solution | Energy efficient windows | Energy efficient windows |
The honest takeaway: plastic film is a reasonable short-term winter fix for drafty or aging windows. It is not a substitute for properly insulated, properly sealed replacement windows — and it has no place on your windows once the warm weather returns.
The Long-Term Fix: Energy-Efficient Replacement Windows
There’s a better answer to summer heat than plastic film, bubble wrap, or any DIY hack. Energy efficient windows with a Low-e glass application can make your home feel more like a refreshing treat and less like a sauna.
Here’s what that looks like in practice. Modern Low-E replacement windows are engineered to reflect infrared heat before it enters your home, reducing the workload on your air conditioning system throughout the summer months. Less AC use means lower energy bills — month after month, season after season. That’s a return that no roll of plastic film can offer!
According to the 2025 Cost vs. Value Report, window replacement in New England carries a 76% return on investment — meaning the upgrade pays back a significant portion of its cost at resale, on top of the year-round energy savings you’ll experience while you’re still living in the home.
Get a Free Estimate and Stay Cool During New England Summers
As an ENERGY STAR® certified windows partner and the only woman-owned James Hardie President’s Club winner in New England, Coastal Windows & Exteriors has helped thousands of homeowners across Massachusetts, New Hampshire, and Maine make the switch from outdated, drafty windows to high-performance replacements that work in every season — without the annual plastic film routine.
So, does plastic on windows help in summer? No — but energy-efficient replacement windows do. They reflect heat, reduce cooling costs, and add lasting value to your home. No tape required.
Ready to find out what your home qualifies for? Schedule a free estimate with our team — or book online and get a $250 bonus.
Frequently Asked Questions About Putting Plastic on Windows in the Summer
Does a window film insulation kit help reduce heat and drafts?
A window film insulation kit offers limited help since it cannot block summer heat or seal drafts well.
What does Energy Star certified mean for windows?
Energy Star certified means a window meets strict government efficiency benchmarks for blocking heat loss and gain. It also means these windows are designed to keep your home warmer in the winter and cooler in the summer.
Does putting plastic on windows actually help with energy bills?
Plastic on windows helps a little in winter, but it traps heat and can raise summer cooling costs.
How much can energy efficient windows save?
Energy efficient windows can save over $500 a year on energy bills, plus added comfort and value.
