How to Insulate Windows for Winter

How to Insulate Windows for Winter

how to insulate windows for winter

Given the fact that windows are responsible for approximately 30% of heat loss during the heating season, it’s no surprise that homeowners are prone to researching how to insulate windows for winter. Ideally, you would utilize these methods to insulate your windows before cold weather sets in, but, luckily, most methods are fairly inexpensive and quick to implement. Here are a few methods you can try.

Window film

There are two kinds of film insulation you can use on your windows. One kind, commonly referred to as window insulation film, attaches to the window frame using tape adhesive. You can buy rolls of the film itself or pre-made kits from most home supply stores. Lightly applying warm air with a hair dryer causes the film to tighten and create an air pocket. The film acts similarly to the argon or krypton gas that fills the space between energy efficient double-glazed window panes. The air pocket created between the film and the window can reduce the passage of warm and cold air through the window panes. This method of insulating has been proven in studies to increase energy efficiency by up to 13% when applied correctly. However, because it attaches to the window frame and not the glass, it might not be the most attractive solution, but it is fairly inexpensive and easy to do yourself, and it’s easily removable. However, you should be cautious when removing it, as the film’s adhesive has the potential to damage the finish of your window frame by lifting some of the paint.

Another kind of film, called low-e film, is adhered directly to the glass of your windows. This film blocks UV rays and can either reduce heat transfer inside or outside of your home, depending on whether the film is placed on the inside or outside of the window glass. Applying the film to the inside of your windows will help conserve more than 50% of the heat inside your home. Applying the film to the outside of your windows can help insulate your home in the summer, as the film reflects between 70 and 80% of heat generated by the sun’s UV rays, preventing that heat from transferring into your home.

There’s another added benefit to the low-e film: because it reduces UV rays and glare inside your home, it can protect furniture, floors, walls and décor from fading or damage related to UV exposure. However, any houseplants you have might suffer from the reduction in UV rays.
Low-e film can improve your energy efficiency and insulation, but it still has its drawbacks. Some homeowners might find the tint or reflective quality (depending on the kind of film used) to be less than aesthetically pleasing. Because the film only covers glass, it will not improve heat loss that occurs because of other insulation issues, such as drafts or cracks in window or door frames. Some films can be removed, but others are permanent, which is important to consider if you’re not an experienced or adept DIYer, as the films can be somewhat difficult to apply. It’s also important to note that low-e film cannot be used with double-pane windows, as they might void the manufacturer’s warranty by causing the different panes of glass to expand or contract at different rates, potentially causing cracks.

If you’re considering using either film, it’s a good idea to test it on a smaller, less prominent window to see if you don’t mind the look of the film or the application process.


Caulking is a great defense against the creep of cold air into your home, but it can degrade over time, creating cracks and gaps that can let in air. To seal these and other small gaps, you can apply traditional or rope caulk. However, in some cases, the original caulk may need to be completely removed and reapplied, which can transform a relatively cheap and easy fix into a much more laborious one.

Weather stripping

Weather stripping is the name for a variety of insulation methods, including door sweeps, draft snakes, felt, v-seal, expanding foam, foam tape. Each method varies in application and use. Felt and foam tape typically come in rolls or sheets and are applied with a self-adhesive backing. Door sweeps are made of either aluminum or stainless steel with plastic, vinyl, sponge or felt brushes and installed to the bottom of doors to reduce air flow underneath doors. Draft snakes (also called draft stoppers) are fabric tubes filled with material that are placed at the bottom of doors or window frames to prevent drafts.

Cellular shades

Cellular shades, sometimes referred to as honeycomb shades, are one of the more energy-efficient shades you can install. These shades are made of pleated, layered materials that are designed to fold up like an accordion. The air pockets in the shades add insulation, reducing the heat loss or transfer out of or into the home. Tightly installed cellular shades can reduce heat loss through windows by 40% or more, and, in warmer seasons, they can reduce excess heat generated by the sun from transferring into your home by up to 80%.

Cellular shades are a great addition to your windows because they are attractive, increase comfort levels in all seasons, add privacy and can even increase your home’s resale value.

Insulated thermal curtains and drapes

Thermal or blackout curtains and drapes are another insulation method that can help keep your home warmer in the winter and cooler in the summer. In the winter, drawing the drapes or curtains can reduce heat loss from a room by up to 10%. For maximum effectiveness, make sure the drapes are installed as close to windows as possible, fall onto a window sill or floor, overlap at the center and seal the drapes on the sides and bottom. These additional measures can reduce the heat lost by up to 25%. In the summer, drawing the drapes during the daytime can reduce heat convection from the sun.

These are just a few methods of how to insulate windows for winter; there are other methods not outlined in this article. For the best results, several of these DIY methods can be combined to increase their effectiveness, such as the addition of both shades and thermal curtains, the use of caulk, etc.

While these DIY methods can help keep your home warmer in the short term, consider planning to upgrade to better insulated windows for future seasons. With today’s selection of more energy efficient window panes, frames and more, your days of wondering how to insulate windows for winter will be a thing of the past.

If you’re interested in learning more about residential glass replacement, contact Missouri Glass.


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