If you are looking to get the most comfort and efficiency out of your window replacement, there are several standards that the products you buy must adhere to. There are always homeowners looking to do the cheapest and quickest job. But you will find that when it comes to windows and doors, the difference in price often means a difference in quality.
So how do you know if a window performs well and will last as long as possible?
There are two main factors to consider when picking and comparing windows:
- All quality windows in Canada adhere to the CSA – A440 standard.
- All quality windows are ENERGY STAR rated.
Because both the Canadian Standards Association (CSA) and Energy Star rely on similar criteria for evaluating windows, usually if a window is good enough to qualify for one standard, it also qualifies for the other. Very rarely will you see a window manufacturer that sells ENERGY STAR qualified windows, that don’t meet the CSA standard.
The best thing for homeowners is that this information is publicly available online:
Understanding CSA standards for comparing windows
As a Canadian window consumer, the windows you purchase should adhere to the CSA – A440 standard. The Canadian Standards association has laid out specific guidelines for window performance in these categories:
- positive design pressure, where applicable;
- negative design pressure, where applicable;
- water penetration test pressure; and
- air infiltration and exfiltration level.
Sometimes you will see windows with ABC ratings. For example, a window that is rated A3, B6, C4 is more efficient and better performing than a window that is rated A3, B6, C2.
One way to recognize whether windows are CSA certified is that they have a CSA logo on the glazing and come with a CSA label that outlines the window’s performance metrics in the four categories mentioned above. But if you look at the picture below, you’ll see that the ratings provided on the label, aren’t the same as the ones used by CSA.
While the CSA-A440 is the minimum standard all windows installed in Canada should comply to, different windows have their own unique Energy Ratings (ER) based on several measurements of performance. Energy Ratings are a more simplified and harmonized way to understand and compare window performance.
Understanding Energy Ratings when comparing windows
A window’s ER rating is calculated on three factors: solar heat gains, heat loss through frames, spacers and glass, and air leakage heat loss. ER ratings rank between 0-50, the higher the rating, the more efficient the window.
The ER number is a balance between heat loss ratings (U-Factor) and solar heat gains through the window (SHGC).
U-Factor is a measure of how much heat a window system loses. Note the use of the word system here. Traditionally window performance was often judged by the R-value of the materials used, but modern windows often use different materials with different R-values, so it is not accurate to measure these values in relation the window as a whole. The lower the U-Value, the less heat is lost through the whole window. Some of the best thermal windows on the market achieve a U-Value of 1 or slightly lower.
Solar Heat Gain Coefficient (SHGC) is a fraction of how much UV heat is allowed to pass through the glass into your home. SHGC can range from 0 to 1, but the higher the coefficient, the more heat your windows gain from the sun. SHGC also has a direct effect on the energy rating of a window. It only makes sense: a window that allows more heat in, is technically more efficient because of it, in turn, requires less energy to keep the home warm.
However, the efficiency of modern vinyl windows is relatively high to a point where windows with higher SHGC ratings can actually overheat rooms even in the winter time. This is especially true for unshaded windows facing south or west, and in homes with high window to wall ratio.
Although it is meant only for comparison purposes, the ER number is still a good indicator of the effect windows will have on your annual heating costs. The lower the number, the more heat is lost and the harder the heating system has to work in colder weather.
ENERGY STAR also uses the ER number to rate whether a window can be considered efficient in different climate regions in Canada.
In order to be considered efficient in Calgary, windows must have a minimum ER number of 29 and a maximum U-Factor of 1.40
Importance of correct window installation
One thing we have not discussed at all in this post is window installation. While “how” your windows will be installed may not be taken into consideration when comparing the quality of the actual product, you should know that correct installation accounts for half of the success of your window replacement. Even the best replacement windows can cause your home to lose heat if they are not installed properly. Consider window companies in Calgary that have good reviews about their installation.