Q: While we were on vacation in England last fall, the owners of our bed and breakfast were switching their summery curtains for heavy, velvet ones — something they said most Brits do to keep their houses cozy in winter. Would it be worth doing that here, where temperatures fall much lower? If yes, what are the best fabrics to use? Could I have some kind of insulating fabric added to my existing draperies?
— Getting Chilly in Scarsdale
A: I plunged via Google into the world of R-values, conduction, radiation and thermal exchange whatsits, and emerged with a multitude of interesting factoids, including these: “Heat as energy moves from warm areas to cool areas”; and “The bigger the difference in temperature, the faster the heat flows”; and “Windows are the biggest sources of heat loss.” Taken together, this means that when you’re toasty indoors and it’s bloody freezing outside, heat is likely to be flowing out of the windows like crazy. How much can draperies help?
One site discussing energy conservation took a scientific approach, with charts and graphs and sentences like, “Where U is the thermal conductance which is the inverse of the more widely known….” To which my response was, “What?” Skipping over the mathematical mumbo-jumbo, the conclusion was that draperies (assuming you close them, of course) can reduce heat loss by about 37 percent on single-glazed windows; 30 percent on double-glazed. Insulated curtains boost those figures to 56 percent less heat loss on single glazing; 48 percent on double-glazed.
Tatyana Tchernov, who owns the fabric and interior design store called By The Yard in Hartsdale (www.bytheyardfabrics.com), says any lined fabric would help keep out the cold, although, obviously, a heavier material like velvet will block more air than a lighter one. “It’s always good to line window treatments,” Chernov says. “We recommend a thermal lining. It’s not heavy, and it doesn’t really affect the drape,” she adds, noting that you can use a thermal lining with any fabric except sheers. And can such a lining be added to your existing curtains or shades? “Absolutely,” she replies, emphatically.
One word of caution about those thermal curtains at big box stores: A friend bought some that had insulating material bonded onto the cotton-linen fabric. After a few years, the foam-rubbery insulating stuff began to disintegrate and peel off. A separate thermal lining seems a much better idea.