There are many reasons to replace windows, but energy efficiency is not the best reason. Replacing the windows in an older house is one of the most expensive energy upgrades you can make. To improve performance of existing windows, consider storm windows, window films, and exterior roller shades before buying replacement windows.
But which option is the best bang for the buck?
1. Replacement windows — the most expensive option
You have three options when replacing windows: full window replacement, insert windows (the old sashes come out and a whole new window inserts into your old window frame), and sash replacement (primarily for double-hung windows, this option requires jamb liners into which new sashes are installed). A typical full window replacement (a window 30 inches wide and 60 inches tall) will run about $400 to $600; insert replacements cost about $300 to $400, and sash replacement kits cost around $250 to $300.
For the time being, tax credits are likely to be available for some window replacements (those with glazing that meets IRS requirements) and a few other window attachment options.
The best place to go to get unbiased information on window replacement options is the Efficient Windows Collaborative.
Remember that you might not need to replace your windows unless they are actually falling apart, if they are unsafe, or if they no longer operate. If your windows are sound and function well, consider other window attachment options.
2. Low-e storm windows deliver a lot of performance
Newer, airtight storm windows with low-e coatings can rival the performance of just about any window replacement. Interior units are easy to install, although exterior units do a much better job of protecting your existing windows. And now you can buy low-e storms with high solar heat gain for colder climates and low solar heat gain for warmer ones. Double- and triple-tracked storms come with operable screen panels so you can easily operate your windows for natural cooling.
For that same size window (30″ by 60″), you can get a low-e storm window, installed, for about $60 for interior plastic single fixed panel (not low-e) to $160 for exterior low-e triple-tracked storm windows.
3. Window films can be temporary or permanent
There are two primary types of window films: more permanent, surface-applied films and the stretch-plastic that you install temporarily to interior window trim. Surface-applied films are now rated by the National Fenestration Rating Council and have a wide range of performance properties: U-factor, solar heat gain coefficient, and visual transmittance. Standard solar control window films run about $80 installed while spectrally selective films are about $125 per typical window.
The stretch-plastic seasonal film kits you tack onto window trim can be installed relatively airtight for better thermal comfort and reduced heating in cold climates and typically run about $15 at any local building supply or hardware store.
4. Exterior roller shades keep the sun out
If keeping the heat out is your main concern, the most effective window treatment options are exterior; you keep the sun out before it gets in. While retractable awnings and even fixed awnings tend to be a bit pricey, economical exterior roller shades are available for as little as $25 per window.
New information resource on window attachments
While the best place for clear, unbiased information and guidance on replacing windows is the Efficient Windows Collaborative, there is a new resource dedicated to information and guidance on window attachments. The site includes information on products to purchase as well as a Q&A forum where you can post any question, including questions (and then get answers) for your particular situation.
Special note: What about lead-based paint?
While most window attachments can be installed without any sort of lead-based paint disturbance or legally-required management, don’t let the issue of loose and peeling lead-based paint slide as you work on any aspect of your home(s), but particularly windows. For more information on managing the lead-based paint hazard, see EPA resources.
All cost estimates presented here are ballpark numbers obtained from discussions with remodelers and manufacturers or actual purchase.