Finding a window to do that in our climate seems impossible, but two Calgary window manufacturers have found the perfect balance.

Linda Rhyason, sales co-ordinator with CWD Windows and Doors says the technology behind the low-E coating: “a double-paned sealed unit consists of two pieces of glass sealed together with air space in between.” What makes these windows energy efficient is the compound sputtered against the glass. CWD uses zinc and titanium depending on which type of window you choose.

“Silver is our active component, says Glen Janiszewski, marketing manager with Gienow Windows and Doors. Regardless of what compounds are used, the outcome is virtually the same. Both Gienow and CWD use low-E coated pane on the outer glass, as it has proven most effective. Add argon gas between panes and watch the R-value increase by stopping convection. It works because, as Janiszewski explains, “argon gas is heavier [than air], creating more resistance and slowing down the escape of heat.”

Gienow offers five different glass options in the low-E department, each with a slightly different purpose. As comfort is the top priority for most Calgarians, Janiszewski recommends the Sol-R Shield 270 or 366. Gienow measures the Sol-R energy performance by a few factors. The solar heat gain coefficient number is based on the assumption a standard double-pane clear glass lets about 0.76 unwanted heat build up in a home. By contrast, the Sol-R Shield 270 only lets in 0.37 and the Sol-R Shield 366 only 0.27—cutting the standard coefficient by more than half. The winter U-factor, measured as the inverse of an R-value, has standard glass at 0.48 or roughly R-2. The Shield 270 cuts this number down to 0.25, while the Shield 366 sits at 0.24 or roughly an R-8 value.

“This is ideal for stopping heat loss. Even though you don’t get as much free heat gain from the sun, you also don’t lose furnace heat in the winter,” Janiszewski says, adding air conditioning use would decrease.

The difference in heat gain doesn’t mean you’re losing out on sunlight. Compared to standard glass that transmits 81 per cent visible light, the Shield 270 lets 70 per cent through and the Shield 366 allows 66 per cent. “You want the visible light transmittance percentage to be as close to that 81 per cent as possible while still having the other qualities,” Janiszewski says, adding the slight tint to the glass is hardly noticeable.

The other Sol-R windows available still outperform double-paned clear glass but may not be fit for Calgary’s weather, where the sun doesn’t hide. “There is a school of thought in cold climate that you want to allow more heat to come through the glass,” says Janiszewski. “In theory this makes sense but with our sunny climate, the rooms would still overheat.” Therefore sticking with the Shield 270 and 366 are still your best bet.

CWD also has two great options, says Rhyason. The low-E, known as the “hard coat,” adds zinc to the production. Low-E typically costs about 10 per cent more than standard clear glass. The TI-R is called a “soft coat” and has the titanium sprayed on the surface. It is roughly 15 per cent more than clear glass. If price is of concern, you can use low-E glass on south- and west-facing windows, but Janiszewski recommends low-E for all windows, as the energy savings in the future will far outweigh the extra cost today.

Although the TI-R is more energy efficient than its low-E counterparts, Rhyason says both reduce condensation on the windows, especially in new homes. “In new home construction, the new wood leaks moisture but the low-E and TI-R windows maintain more equal value of air,” she says. Basically, the temperature difference outside and inside is not as extreme, preventing window “sweating.”

Another benefit with the coating from both Gienow and CWD is the protection it provides on furniture and flooring.

Because titanium makes the glass more reflective, UV rays bounce off the glass hindering sunlight damage to fabrics and woods.

With more benefits coming to light, it is no surprise that low-E coated windows are becoming increasingly popular with new construction homes and home upgrades.

So this winter, spend less time getting hot under the collar about utility bills, and more time and energy  enjoying your home.