Bubble wrap: a cheap way to insulate drafty windows

A few weeks ago my friend Tania messaged me that her husband had gone rogue while she was out of the house and covered the living room windows with bubble wrap. She attached this photo:

I snickered and asked her if this was his idea of Christmas decorating.

Nope, she said. He’d read on the Internet that bubble wrap is a good insulator, and that covering your windows with it helps save on heating costs.

I wasn’t immediately sold on the idea. I’ve used clear window insulating shrink film for years, and while I don’t like the fact that it can’t be reused from year to year, I like the noticeable temperature improvements. When I first moved up north, I lived in a co-op house where we put up reusable insulating window film ever winter, and while they provided the same comfort level, years of folding and unfolding the plastic had made the film cloudy. As a result, less light passed through and the view out the windows was best described as “perpetually foggy.” It was always a psychological relief when we took them down in the spring.*

Bubble wrap seemed like an even worse alternative.

But then I searched the Internet and read that using bubble wrap with large bubbles on your window doesn’t obscure the view as much. And in bathrooms and bedrooms, small-bubble bubble wrap on your window can do double-duty as a privacy screen.

Besides, I remembered that I can’t see anything interesting out the single-pane windows in my basement anyway, since they’re all below ground level.

So I decided to give bubble wrap a shot.

I started out with some large-bubble bubble wrap that I’d received with a shipment of secondhand videos. I’d been saving it for dropping off at the UPS store for reuse/recycling (not all UPS stores accept these materials), but this use was just as good. The bubbles are about 1″ in diameter:

The sheets were already just about the size of my windows; I just had to thrim a little off the ends. Then I sprayed some water on the window in my sewing room and pressed one of the sheets to it with the bubble side facing the window and the flat side toward the room. (This position allows the spaces in and between the bubbles to trap air, providing insulation.)

As you can see, I didn’t trim the plastic for a precise fit. If you want to hold the bubble wrap to the window using only water, you need to trim that so that not much hangs past the glass itself. Water isn’t as good an adhesive against metal as it is against glass (and you definitely wouldn’t want to use it against wood). However, I wanted the overhang because air leaks through the tiny gaps between the window and the frame, and I wanted to cover those gaps.

Since the windows in my basement are really leaky, I decided to go for a double layer of bubble wrap for better insulation. For the second layer I decided to use bubble foil, which provides slightly better insulation values because its foil side reflects heat back into the room.

“Wait a minute!” you may be saying. ” are you the one who was complaining that bubble wrap up skiers the view to the outside? Foil will not only block the view, but keep any light from entering.”

That is true, which is why would normally recommend doing this. but it so happens that my sewing room window is located in such a shady spot that barely any light enters through it anyway; if  I’m in it in the middle of the day and turn off all the basement lights, I can’t see a thing inside the room. So blocking the light isn’t really a problem.

I installed the second layer using the sprayed water method, but the foil was too stiff and heavy for it to work well. (In the picture above, you can see how the foil bulges out at the top right  where it refuses to stick to the first layer of bubble wrap.)

So I  secured the layer with clear packing tape, which I have circled in the picture below because you can hardly see it with the naked eye.

In the laundry room, I (with the help of Companion, who had wandered into the basement to see what I was up to) installed layers of clear bubble wrap over the windows, skipping the foil since the windows there let in light.

There was definitely less of a breeze next to the windows after installing the bubble wrap. Whether this translates into cost savings is yet to be determined, but the increased comfort was worth the effort.

*It turns out there is a clearer alternative to the plastic we used: vinyl. Having not used it myself, I can’t say how well it holds up year after year. I imagine it would hold up pretty well in windows that don’t get direct light, but start yellowing or crackling where exposed to bright sunlight – but these are just educated guesses.