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05/02/2014 11:57 EDT | Updated 07/02/2014 05:59 EDT

Air leakages from windows can affect comfort of home; check weather stripping

VICTORIA - As the winter months fade to spring, and eventually summer, more homeowners will feel the urge to fling their windows open wide and let in the fresh air, but for those with older windows this seasonal gesture may not be possible.

Every summer Norm MacDonell, sales manager for Victoria's Van Isle Windows, faced a dilemma with his 1945 house. The old single-pane, glazed windows had been painted shut, but MacDonell's wife wanted to keep their windows open all summer long. They ended up buying new windows.

"Energy efficiency was kind of last on her list because of where we were starting from, which was a small, well-insulated house," says MacDonell. "With our new windows, when I go home in the summer, every window in the house is open and she tells me how much she loves her new windows."

While energy efficiency has become an important factor when it comes to purchasing new windows, MacDonell says there are a variety of factors affecting which product homeowners choose and the type of problems they may have had with their old ones.

"It depends on the person and the product," he says. "Sometimes in the case of old wood windows, there may be some maintenance issues. There may be some wood rotting, or maybe painted shut, or conversely they may be rattling in the wind."

With aluminum windows the weather stripping can fail, which leads to maintenance issues. Condensation can form on inside panes, which can lead to mould along the frame.

The needs of a homeowner can vary depending on the climate. According to MacDonell, a home in Alberta has much different needs than a home in Victoria because of the weather, for example, and energy efficiency becomes a higher priority.

Windows also create possibilities for air leakages, which not only leads to higher energy bills as homeowners deal with drafts, but also affects the comfort of a home.

"Many homes have windows with larger windows and bay windows, and in the wintertime that's just uncomfortable because there can be drafts," says Mark Hutchinson, director of green building programs at the Canada Green Building Council.

"In newer homes the drafts can be harder to pin down and observe, but anyone who has ever lived in an older home knows drafts can make a huge difference in the perceived level of comfort."

Hutchinson says a homeowner may have their thermostat set at 20 C, which may be perfectly comfortable without a draft, but with a draft you might turn it up to 22 or higher.

How a window opens can also affect the possibility of air leakages. Hutchinson says windows that slide to open have a greater chance of drafts than those that open on a hinge.

"When it is hinged you have a locking mechanism that assures it is pulled tight against the gasket and that will provide a better seal than a sliding window can," he says.

With so much variety in the technology and materials used to build windows, it can be difficult for a homeowner to decide what product best suits their needs and their home.

According to Hutchinson there are several metrics that are used to help communicate the solar heat gain and air leakage of windows.

"The everyday person doesn't necessarily know or understand all the factors that affect a window, but there some rules of thumb," he says. "In the LEED Canada ratings system, which is a rating system that assesses the criteria for new homes, there are criteria for windows specifically, and it looks at what is called the energy rating. It was developed for window manufacturers to assess their windows and it takes all the other metrics and compiles them into one number and a higher score is better."

For a home to even qualify for LEED certification the lowest energy rating a homeowner needs is 21 for windows, 25 for an even better window and 29 is considered a very good product.

Hutchinson says the best thing a homeowner can do is look for an Energy Star label, which is applied to the top 15 to 30 per cent of energy-efficient windows.