Dear Jim: Our house has its original single-pane windows, and we always feel chilly near them. I got quotes on having them replaced, but I can’t afford it now. What can I do in the meantime to improve the efficiency of the old windows?-Pete N.
Dear Pete: I’m not surprised to hear you feel chilly near old single-pane windows on a cold day-they typically have huge heat loss and cold-air gain because of poor caulking and weather stripping (if there is any to begin with). You probably also feel hot near them during summer.
The most significant heat loss and chilly feeling occurs on a clear winter night. The R-value is a higher-the-better number that shows the ability of insulation to resist the transfer of heat-of a single pane of glass is only R-1, as compared to an insulated wall at R-20.
There are many things you can do on a limited budget to improve the year-round efficiency of your windows. Before you attempt to make any improvements though, first check the caulking and weatherstripping on the windows and ensure the framing is not deteriorated. If you find subpar conditions, fix them before you attempt any improvements, or your hard work won’t be worth much.
Adding storm windows, either interior or exterior, can more than double the energy efficiency of your existing windows. Custom-made, multi-track storm windows can often cost almost as much as totally new windows, so make your own using clear acrylic sheets. Another advantage of using acrylic instead of glass is that acrylic blocks most of the sun’s fading ultraviolet rays.
Exterior storm windows can be made with 1-by-2-inch lumber, acrylic sheet, and foam weather stripping. If you size them to fit inside the wall opening and paint them to match your existing window frames, they will look like part of your windows. The compressible foam weather stripping should hold them in place in the opening. Push them in as far as possible to minimize the air gap.
To install interior storm windows, use a kit with magnetic seals. The magnetic section of the seal attaches to the acrylic sheet with an adhesive backing, and the steel strip attaches to the window frame. This allows you to easily remove them during summer for ventilation, but if you use air conditioning most of the summer, just leave them up year-round.
Another option is to install insulating window shades or curtains to increase the overall insulation level of the window opening and to block the radiant heat loss from your skin through the window. Something as simple as a pull-down pleated shade can help quite a bit. Even closing Venetian blinds blocks your skin’s exposure to the cold outdoors.
Some of the most efficient window shades can add R-6 insulation to your windows. These are multilayer roll-up shades with a heat reflecting airproof inner film layer to greatly reduce radiant heat loss (or gain during summer). I also close mine on a hot summer day. These shades are particularly effective because the side edges slide in channel tracks, which reduces the amount of air that circulates against the cold glass.
The newest energy-saving permanent window films are also effective for reducing wintertime heat loss.
These films have just a very slight tint so they can’t be detected and use the same type of microscopically thin low-emissivity metallic coating as expensive replacement windows. Simple vinyl static-cling film will also help a bit. But before installing anything on double-pane windows, check the window manufacturer’s warranty regarding film application.
Do-it-yourself energy-saving film installation kits are available at most home improvement stores. Depending on your climate, you may want to select a darker tint if summertime heat gain is your most significant concern. Because the sun is higher in the sky during summer, installing window awnings for shade and a lighter film on south-facing windows will allow for some passive solar heating from the lower wintertime sun.
A final option is to install a tilt-in double-pane, sash-only replacement kit. If your existing frames are in good condition, this will convert your old windows into very efficient ones. This option also provides the convenience of tilt-in sashes for the ease of cleaning both sides of the window glass from indoors.
Send inquiries to James Dulley, Illinois Country Living, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com.