Although slider windows are not as efficient as casements, they are still a very popular choice with homeowners in Calgary. What sliders lack in performance ratings compared to crank windows, they very well make up in their price.
And even though they are a cheaper option, most slider windows still meet climate requirements for harsh Canadian winters, and can be considered efficient.
The trick lies in figuring out which company’s windows do meet the necessary requirements, and which company’s windows fall short.
These are the key points to keep in mind about slider windows:
- Although slider windows don’t perform as well as casements, they cost less and still provide acceptable levels of performance.
- When comparing slider windows consider BOTH their heat loss conductivity (U-Factor) and energy rating (ER) for a true sense of how the window performs.
- Because slider windows are operated manually, proper operation is crucial to longevity and performance of the window.
Let’s break it down into more detail.
Slider or casement windows in Calgary. What should you get?
As we mentioned above, slider and casement windows differ in performance levels and price. But why? A lot of it has to with how these types of windows were designed to operate. A big area of heat loss in any window is the place where the moving part meets the frame. In sliding and hung windows that space is made more efficient with the use of fiber weatherstripping.[hypotext target=”your-target-id”] [expand] [/hypotext] [hypotext id=”your-target-id”]Because casement windows open at an angle relative to the frame they can also use weatherstripping to fill the gap in a closed position. But a far more effective component utilized in modern casement windows are soft compression seals. When the window is closed the seal evenly fills the space between sash and frame making for an airtight unit with superior performance ratings.
Another performance variable is the difference in sash size. Because casement windows only have one sash, they only have one insulated glass unit. Even in single slider windows, there are still two sashes which need to fit into the depth of the window opening. The individual sealed units in slider windows have to be much thinner and are therefore less efficient than a single, bigger sash in casement windows.[/hypotext]
What you should know about tilt-and-turn sliding windows
When looking at new sliding windows, customers often come across tilt-and-turn windows. The sashes in these units can be unlatched to turn at a 90-degree angle to the frame, much like the sash in casement windows.
Although this feature looks very modern especially in a double slider, homeowners often misunderstand its true purpose. While these windows can give you a beautiful unobstructed view, the turn-in in function is intended as a maintenance feature. It allows for cleaning of the outer side of the window from the inside of the house.
You shouldn’t keep the sash in a turned-in position as the weight of the sash can cause stress on the frame resulting in deformation or even breakage. This is especially crucial in triple pane slider windows because their sashes are much heavier.
Check out: Common Problems With Slider Windows
How to compare slider windows
Regardless of the window style or type, all windows you consider should be ENERGY STAR rated. ENERGY STAR is an international organization that classifies and rates energy efficient products, from household appliances to building materials.
For windows and other fenestration products, ENERGY STAR has broken Canada up into three distinct climate zones. Edmonton is located in climate zone 2. As such, to be considered efficient in Calgary, any window must have a minimum ER rating of 29.
ER Ratings are a value given to windows, based on a calculation of different performance factors. These include the U-Factor and Solar Heat Gains. The ER rating has been devised specifically to make it easier for consumers to understand and compare window performance from different manufacturers.
U-Factor is a calculation of how conductive a window is, how it is affected by convection heat loss and the emissivity of the glass in the panes. At the very basic level, the lower the U-factor, the better your window is at keeping heat inside the home.
SHGC: The Solar Heat Gain Coefficient measures how much heat from the sun a window gains. Although ideally, you want as much heat from the sun in the winter months, most modern windows with high SHGC end up overheating the home. High SHGC factors are great for windows that see very little direct sunlight and can maximize energy gains in those places. The lower SHGC, the less heat from the sun your windows let through.
ER Ratings or U-Factor: What’s better for comparing windows?
You can often see window ratings represented in either one of these values. But which one is a better representation of a window’s performance?
An ER number is a more encompassing measure of how a window “transfers” energy. The more heat it gains rather than loses, the more efficient a window is considered. Therefore it always important to look at the SHGC number to see how it plays into the window rating.
The U-Factor on the other hand assesses a window’s resistance to heat loss. This is especially important to consider in Canada as we often have longer nights in the winter where it is essential for a home to retain as much of its heat as possible, while not gaining any energy for the sun.
A high ER number may just mean a window gains a lot of energy from the sun. A low U-factor will mean that a window is great at keeping the warm air in.
We have compared performance ratings from top Calgary window companies: Canadian Choice, Ecoline Windows, All-Weather Windows, Lux Windows, Supreme Windows, and Cossins Windows.
We compared single slider windows with Low-E applications and gas fills. Take note of each window’s U-factor, ER rating, and the company’s value range for each performance metric. It is often possible to improve a window performance with additional features.
Not seeing a company you’re interested in? This information, as well as a full list of Energy Star participants and their product ratings, is available on this Natural Resources Canada website.
You will probably notice right away, that a couple of companies don’t have information available for their slider windows. This information is not listed under the company’s registry on the NRCan website. This could mean one of two things: either slider windows from that company are not Energy Star rated, or the company gets their slider windows from elsewhere. But usually, the former is true. Slider windows usually rank at the borderline levels of acceptable performance. That is why they often require additional features to improve their performance. As you can see by the chart some company’s slider windows barely reach that level, even with additions like Low-E and gas fills.
If you are considering slider windows for your replacement project, make sure that the ones you get meet the performance requirements for your climate zone.