The Hidden Energy Loss Most Toronto Homeowners Ignore
Winter is a harsh season in Toronto. Keeping a home warm is a major issue from the bone chilling winds that roll off Lake Ontario, to the weeks of sub zero temperatures from December through March. When faced with cold weather, most homeowners will do what you would think: turn up the heat, pile on the blankets and frown when the bill comes.
What few of them know is that much of the heat they are paying for is going out the window – silently, invisibly and in a continuous stream.
This is far from a minor inefficiency. Energy professionals estimate that windows and doors may lose up to 30% of the heat in a home. That’s not only uncomfortable, it’s costly in Toronto winter. But, it is one of the most neglected issues in everyday household energy use.
Why Windows Are the Weak Link in Your Home’s Thermal Envelope
The “thermal envelope” of your home is everything you have between the inside and outside – walls, roof, floors and even your windows! Walls are usually filled with high R value insulation which is the amount of resistance a material can offer to the flow of heat. The latter, on the other hand, is limited by its nature. Even an effective double pane window only has a small portion of the R value of an insulated wall.
This is important because warmer places always transfer to cooler places. During Winter, the heated indoor air is never happy to stay home. This is the quickest way for it to get there – either through the glass, the frame, or any openings in the seal around the window unit.
There are three main ways this heat escapes:
Conduction – The heat flow passes directly through the glass and frame material. Single pane windows are particularly poor at this and even older double pane windows leak a lot of heat through conduction, particularly if the frame is aluminum (a very conductive material).
Convection – When the windows are cold, cool air rushes down towards them and brings warm air from the room up to the glass. These are “cold spots” that are hard to deal with and make your heating system work harder to deal with.
Air infiltration – Cold outdoor air can penetrate gaps and cracks directly around window frames. This is most important and most overlooked. Over time, home windows move, seals deteriorate, and weatherstripping becomes worn out. The effect is that you have a window that’s continually letting cold air out of your house.
The Signs You’re Losing Heat Through Your Windows
Many homeowners are unaware that they are experiencing window heat loss until they are made aware of the signs and symptoms of window heat loss. The most significant signals are:
When sitting near a window, even with the heat on, you notice a draft. This is the convection effect in action – the cold glass is drawing the cold air towards it and setting up a cold draft area.
Even though you haven’t changed any of your heating behaviours or your family size, you have noticed your heating bills have been growing year on year. Increases in this are usually indicative of deteriorating window seals and weatherstripping.
In cold snaps, condensation or frost may form on the inside of your windows. This means that the surface of the glass is approaching dew point temperature which is a sign of poor insulation performance.
You can see daylight around the window sills or you can detect a draft on a windy day by running your hand around the window.
During cold weather, your HVAC system is constantly in use as it tries to keep the set temperature of the house. This may indicate that your furnace is not keeping up with the heat loss.
What Age of Window Are You Working With?
Windows vary in efficiency, and when your house was built (or your windows last replaced) can give you a good indication of their efficiency.
Pre-1980s single-pane windows
Are the worst offenders. These have virtually no insulating properties and cause huge heat escape in homes. If you still have original windows in your Toronto home from this period of time, it is critical to replace them.
1980s-1990s double-pane windows
They were significant advances at time of introduction but many of these have been replaced, and are now 30-40 years old. Over time the seals between the panes can become damaged and the insulating gas (often argon or krypton) can leak out and be replaced by normal air or moisture. The most obvious indicator is if there is a foggy or hazy appearance in between the panes.
2000s and early 2010s windows
may not be in poor condition at all, but it’s best to get them checked out. Even if you have a relatively new window, seal failures, frame warping and worn weatherstripping can compromise its performance.
Modern energy-efficient windows
Those featuring the Low-E coatings, triple panes, and insulated frames – are the standard now. They are specifically engineered to reduce all three types of heat loss, and are a significant improvement to older homes in Toronto.
What You Can Do About It
Luckily, there are solutions to the problem of window heat loss at home and they can vary from do-it-yourself to replacing the entire window.
Weatherstripping and caulking
These are the most affordable and effective window upgrades for older windows. Worn window weatherstrips and failing window/frame caulking can drastically increase air infiltration and can be fixed by replacing the weatherstrips and re-caulking around the window frame. It is a project that a homeowner can easily complete as a weekend project.
Window film
Is a cost effective solution which can be applied to existing glass with a thin layer of insulation. Heat-shrink window film kits can be installed on single glazing and will help significantly with heat loss, especially when installed on windows in Toronto.
Thermal curtains and cellular blinds
Form an insulating air gap between the window glass and room. These can be opened at night (when heat loss is greatest) which can provide a significant reduction in the cold zone effect and energy savings.
Window inserts
Are an intermediate option – interior storm windows that fit inside the existing window frame. Less disruptive than a replacement and can significantly enhance performance.
Full window replacement
For very old or excessively damaged windows, it is the best long-term remedy. Today’s energy efficient windows (those with the ENERGY STAR label, which applies to window types and climate zones specific to Canada) can significantly outperform older and traditional windows, and can pay for themselves over time due to their benefits in reducing heating costs.
The Toronto Climate Factor
Let’s emphasize the relevance of the issue very specifically for owners of Toronto homes. Under Canada’s energy rating system, Toronto is categorized in Climate Zone 6, which is one of the harshest climates in terms of the country’s heating requirements. Windows are rated according to climate regions, and enough in a more temperate Canadian locale, will not suffice in a Toronto January.
Also, freeze thaw periods cause deterioration of window seals and frames. There is small water in small cracks that expands when freezing every winter, enlarging the cracks a little. This may lead to extensive damage over a several decades’ time even with properly installed windows.
If you’ve never had your windows professionally checked for their performance in the last 5-10 years, you should want to find out just how much they’re leaking.
FAQs : The Hidden Energy Loss Most Toronto
What is home heat loss through windows, and why does it matter?
Window heat loss is heat escaping from a house to the outside from the window glass, window frames or window seals. This is significant because up to 25-30% of your total heating needs can be going out the window, literally, and that will be a big part of your energy bill.
What are the signs of heat loss through windows in my home?
Soothe the interior glass of the double pane windows, condensation or frost near the windows, drafts under the windows, higher heating expenses and heating system operating continuously without attaining the required temperature are common symptoms.
How can I check for window heat loss myself?
On a cold windy day rub the inside of the glass on the edge of your window glass. If any change in the air movement is detected, it is considered air infiltration. Alternatively you can flame an incense stick close to the frame, if the smoke fluctuates, there is a draft. An energy audit performed by a professional using the thermal imaging scan will yield more accurate results and will reveal all hot spots.
Are older windows worth repairing, or should I replace them?
This will rely on the condition of the window and its age. Rescue of structurally acceptable frames by replacement of the weatherstripping and caulking could extend their useful life significantly. Single pane windows, double pane windows with failed gaskets, however, are much more costly and worth considering for replacement, particularly since Toronto’s heating requirements.
What type of windows are best for reducing heat loss in Toronto?
Check for ENERGY STAR windows which are rated for Climate Zone 6 (Canada) The additional benefits of lower heat loss include triple pane glass, Low-E coatings, argon- or krypton-filled glass and insulated (non-metal) frames. A smaller Uf the better the insulating properties.
How much heat is lost through windows in a typical Toronto home?
While the age and window condition of a home are important factors, it is generally estimated that windows and doors can account for 25-35% of the home’s total energy loss in older houses in Toronto. That number can be even higher if the original single pane windows have been retained in a house.
Window film does help curtail heat loss?
To some extent yes. The second level barrier of film on interior windows also helps to minimize convective heat loss and air infiltration. It won’t match the efficiency of a new double or triple pane window, but it can be a short-term solution until those new windows can be installed.
How often should I replace the weatherstripping on my windows?
The life expectancy of weatherstripping ranges from 5 to 10 years and is related to the material of its construction and the amount of exposure it receives. For Toronto’s climate, with heavy temperature shifts in the windows as well as moisture, every year it’s a good idea to check. Change it when it becomes visibly cracked, compressed, and/or when drafts are detected along the edge of the frame.
Can thermal curtains really make a difference for window heat loss?
Yes. Heavy thermal curtains or quality cellular (honeycomb) blinds provide an insulating air space that can save 10-20% on heat loss through the window when shut. Its greatest effect is achieved by closing them at night when outside temperatures have fallen and rates of heat loss increase.
Is window replacement covered by any rebates in Ontario?
The energy rebate programs in Ontario have undergone multiple changes. Recently, the Canada Greener Homes initiative has been providing grants for window energy upgrades and other energy-efficient additions. Please make sure to check the current offerings at Natural Resources Canada as well as Enbridge’s Home Efficiency Rebate program and amounts change frequently.