Replacing single-glazed windows with new double-panes used to be the energy-wise solution. Now there’s a less expensive alternative.
WASTE NOT | When it comes to improving the energy efficiency of older buildings, one of the major things we tend to think of is replacing single-glazed windows with double-glazed models. A CMHC report on energy savings proves otherwise. In 2004, their case-study research found that replacing doors and windows averaged just 12 percent energy savings compared to 34 percent from insulating the foundation and ceiling plus draftproofing the rest of the house, 14 percent from insulating exterior walls and 39 percent from upgrading the furnace.
So it seems that dumping your single-glazed windows in the landfill and installing double-paned ones, which will have to be replaced if the seal fails, is not only more expensive but it’s also less sustainable.
“The most energy efficient window is one which is responsible for less consumption of energy across its entire life cycle, including its manufacture, shipping, time in service and its eventual disposal or recycling—not just its performance rating on the day it was installed,” according to the Vancouver Heritage Foundation.
Fortunately there are now better alternatives for making single-glazed windows more energy efficient than unsightly shrink film. When the David Suzuki Foundation renovated its Vancouver office a few years ago, B.C.’s Titan Window Films (www.titanwindowfilms.com) applied 3M’s Prestige 70 solar control film to its windows to reduce solar heat in summer and furniture-fading UV light year-round. Another 3M film, Amber 35 Low-E, reduces heat loss by 30 percent in cold weather, but it has a reflective tint that changes the look of the window and makes it difficult to see outside at night.
A less expensive alternative to 3M is Energy Film, which costs $46.20 for a four-by-seven-foot roll. Applied without adhesive so can be easily removed or adjusted, Energy Film is nonreflective, virtually colourless, stops 98 percent of UV radiation and 65 percent solar heat. The amount of heat escaping during cold weather is reduced from 5°F (around 2.8°C) right outside the window to 10°F (around 5.5°C) a foot away. Check out the website for more information, dealer locations or to get a free sample to see what it looks like: www.energy-film.com. —Felicity Stone