According to the US Dept of Energy, you can save 30% on your heating bill by spending some time winterizing your windows. Most of these projects are DIY and inexpensive ways to save on your heating bill.
Sealing your windows for energy efficiency – the basics
Caulk around the frames inside and out. This will eliminate drafts and protect the outside frame from the elements, extending its life. Light a candle and place it 4-6” from where the window frame meets the wall. If the flame flickers, there is air infiltration, and it needs caulking. If the gap is large, use wood putty. This one thing can stop a lot of heat loss, so always caulk before doing anything else!
Put up storm windows when you take the screens down. Clean dirt and dust out of the tracks to make a good seal. I remember my dad doing this every fall. He’d drag all the storm windows out and place them up against the garage door. Then we’d wash them (I’m sure he had to rewash mine!), and he’d spend a weekend putting them in place.
Low-e film and wrapping your windows
Install low-e film on the insides of your windows. This reflects heat back into the house while allowing you to still see outside. In summer or warm climates, it keeps heat from coming in, so the house stays cool. Low-e coatings come on most new windows these days, but you can install film on old windows.
You can put plastic shrink-wrap over the windows inside. Attach it to the frame and heat it until it is not wrinkled anymore. You do not lose your view, and it creates an air space that acts as insulation. Be sure to wash your windows first!
Bubble wrap and energy efficiency
Commercial greenhouse owners use large pieces of bubble wrap on the inside walls as insulation. You can do this at home, too. Cut pieces the size of your panes, spray a little water on the window, and put the wrap in place. You can also use double-sided tape. This works well on windows you usually keep covered with drapes or curtains, since you can’t see out of them. I am using bubble wrap on my skylights this year to keep the greenhouse heat from going straight up and out.
Your curtains – first line of energy efficiency defense
Speaking of curtains, use them. Windows coverings are a great investment and add to the character of the room, beautifully saving you money on your heating bill. Be sure curtains cover the entire frame and don’t just sit inside the frame covering the glass. Quilted blinds, with an air space between two layers of fabric, can be custom made to fit inside the frame for maximum heat retention.
If it’s in your budget, replace old single pane windows and windows over ten years old. Window technology is always advancing, and they only get more efficient every year. Install double pane windows always. Wood or vinyl frames are the most efficient. I bought vinyl frame windows at Lowe’s when I remodeled, and I am very happy with them.
Know how to read a label on a new window. There are certain criteria for where you live, the orientation of your house and the placement of your windows.
Keep an eye out for energy efficiency incentives
As always, check for tax credits and other incentives when buying windows or doing an energy efficient upgrade of any kind. Energy Star, DSIRE, your local utility and your window salesperson can answer your questions and save you even more money!