Does Plastic Window Insulation Work?

Kits

• Window insulation kits are cheap and easy to use. They typically include large sheets of clear plastic film together with some adhesive tape that's sticky on both sides. To apply the kit, you just cut the film as needed with a pair of scissors, then attach the film to the window frame with the tape and heat-shrink the film with a hair dryer to get rid of any wrinkles.

Performance

• According to the New Zealand government's EnergyWise site, window insulation kits can offer reduction in heat loss similar to much more expensive alternatives like double-glazed windows. The plastic in the film is a much poorer conductor of heat than the glass in the window, so just like the air in the gap in a double-paned window, it reduces the rate at which heat leaves your home.

Duration

• Window insulation kits are generally designed to last for a single season, although they may remain functional for a much longer period of time if left undisturbed. Condensation can also be a potential problem with plastic window insulation; in some cases it can encourage mold growth, which is highly undesirable. To prevent condensation buildup, the film must form a good seal with the frame and the paint must be in good condition. Drilling a breather hole from the outside at the bottom of the frame may also be helpful.

Considerations

• Plastic window insulation does work. In some cases, however, it may be an undesirable option. If the window is situated in a location where pets or children could injure the film, if you need or like the view, if the wooden frame is damp or has paint damage, and if the frame and the pane are more than 0.2 inches apart, the cons of plastic window insulation could outweigh the pros. Ultimately, whether plastic window insulation is your best bet depends on your budget, the level of efficiency you need and your circumstances.