An insulating window film applied over a window can help the window retain up to 55 percent more heat in winter, potentially reducing your heating costs up to 30 percent. These films are less effective at reducing summer heat gain, though.

Does plastic on windows keep heat out?

Savings in Energy and Money Leaks around windows can lead to uncomfortable drafts and energy losses. … They can also eliminate air leaks around the window if they extend over the woodwork, and this extra layer of plastic adds another layer of insulating air to reduce heat loss through the window.

What can I put on windows to keep heat out?

Aluminum foil is really easy to use and very cost-effective. Simply place it over your interior glass windowpane and seal the edges with tape. Its resistance to heat helps prevent most of the sun’s heat and glare from getting into your house.