Saturday, November 11, 2017 1:00 am
Shades OK if not fixing windows
Dear Jim: I should replace my old windows for winter, but I cannot afford more debt now. Is installing insulating window shades or curtains a viable alternative and which types are best? – Carol D.
Dear Carol: Old windows can account for a substantial amount of heat loss. This is because a single pane of glass has an insulating value of only about R-1, whereas an insulated wall may be R-17. The window will lose 17 times more heat per square foot than the wall. Also, there is air leakage around windows which further increases heat loss and creates chilly drafts.
Another indirect energy loss from windows, even double-pane ones without low-e (low-emissivity) coatings, is radiant heat loss. Even though the room air is adequately warm for comfort, you feel chilly near the clear cold glass. When someone feels chilly, they often set the furnace thermostat a little higher making the furnace run longer and using more energy.
The savings from installing insulating shades and/or curtains often provides a much faster payback than expensive replacement windows. Many people still choose replacement windows because of cleaning convenience, less furniture fading, nice appearance, or their old windows are totally shot.
The additional insulating value from indoor window coverings can range from R-1 to R-5, but the insulation is only part of the story. Insulating shades which have the edges trapped in vertical side tracks are most effective. This reduces the room air flow around the shade and across the cold glass to save energy and reduce window condensation.
Last fall, I installed Warm Window insulated Window Quilt shades in my home office where I am writing this column. I realize a significant overall savings because I feel much more comfortable in this room. I am able to set the furnace thermostat three degrees lower than before and not be chilly.
These shades use a quilted, multilayer fabric with heat reflective film in the center. This layer reflects the radiant heat back indoors and minimizes air/moisture migration through the fabric. The plastic side tracks stick to the wall opening with double-sticky tape, so they were easy to install. A pull rope is used to roll them up under a matching fabric cover box.
Making Roman shades yourself is another attractive and efficient option and an interesting family project. Use as many material layers as possible so it still folds up. These are more applicable for smaller windows because of their bulkiness.
Insert some type of reflective film near the center layer. The film does not have to be thick to be effective. Reflective Mylar is a good choice and easy to find at most craft stores. Also, many efficient Roman shade do-it-yourself kits are available on the internet.
Another option is a lightweight cellular pleated shade. When it is hanging down over the window, the cells open up to create insulating dead air spaces. Some typical-looking blackout window curtains use a dense weave to block 99 percent of the light, most air migration and provide substantial insulation value. Compare the thickness of the weaves when selecting them.
James Dulley's column appears monthly. Send inquiries to James Dulley, The Journal Gazette, 6906 Royalgreen Drive, Cincinnati, OH 45244 or go to www.dulley.com.