Cellular shades, also known as honeycomb shades, are the most energy-efficient and insulating window treatments. Their honeycomb structure is made of soft fabric that forms layered cell pockets. These pockets trap air, creating a thermal barrier that reduces heat loss in the winter and blocks heat gain in the summer. For even greater insulation, consider double- or triple-cell varieties. Side-tracked cellular shades, which seal the edges of the window frame, can further minimize air leaks and maximize energy efficiency.

If you have bubble wrap lying around the house and you don’t care about the odd look, taping bubble wrap over a window is a very affordable way to insulate it. Another inexpensive option for insulating windows is to add new caulk around the glass. This step quickly cuts down on air drafts for older windows, and a tube of caulk only costs a few dollars. Adding plastic shrink film around the glass is another cost-effective option. You can purchase a kit of plastic film for a few dollars per window.

Applying window security film yourself is possible, but we don’t recommend it. This task is simple in theory, but getting the product to sit on your windows evenly and without bubbles underneath is challenging for DIYers who lack the necessary experience and tools. You might save money on labor by applying it yourself, but you might also end up with a film that doesn’t look appealing, prompting you to start over and spend the money on a professional installation anyway. Plus, most window film manufacturers will void your warranty if you install the product yourself.

The most energy-efficient windows are double—or triple-pane windows with low-emissivity (Low-E) coatings and gas fills between the panes. These windows reduce heat transfer, prevent drafts, and help maintain a consistent indoor temperature. But if replacing windows isn’t in your budget, pairing your existing windows with insulating window treatments can still make a noticeable difference in home comfort and monthly bills.