Window efficiency by window style

Improving energy efficiency in windows is a primary goal for most window manufacturers, and there are many technologies that make windows more efficient. However, if we were to ignore the technical side of windows and rate them purely by window type, then we would be considering only the traditional properties offered by the nature of the window.

Is there really a difference?

When it comes to maximizing the fight against the weather, different window styles will show differing energy-efficiency performance scores. However, you probably would not notice it on your heating bill, or the level of comfort in your home. The differences from one window type to another are very small.

Historically - vinyl window energy efficiency by window type has been as follows (most efficient to least efficient).

1. Picture Windows
2. Casement, Awning & Hopper Windows
3. Single and Double-hung Windows
4. Single & Double-slider Windows

Today - The strive for window energy-efficiency equality

Window manufacturers have become very good at levelling the window style playing field to make all window types equal. And although many believe that certain window types offer better energy efficiency than others, it really depends on the brand you are looking at - keep in mind, by their nature (non-operational) picture windows are certain to be the top performer every time.

Below is a table comparing 3 local Ottawa window installers (they have been listed incognito to avoid bias) that sell 3 different brands of windows. Using the available specs at NRC Canada Windows, each company’s standard line of windows (vinyl, double-glazed, Argon-filled) were compared. Window types are listed in order of their best energy efficiency.

Results

As you can see each company shows a different order for best ER performing window type - picture windows being the exception.

More information about window energy-efficiency

Making them equal to technology

Since ER energy efficiency is calculated with a window’s heat gain, heat loss and insulating factors, it is possible to rebalance a window technically through glazing, coatings and gas fills in order to achieve a closer overall energy rating to match different window types.

For example, to accommodate the loss of efficiency in a slider and hung window, manufacturers offer optional upgrades of the inert gasses between the panes (ie. from Argon to Krypton).