Natural Resources Canada
Symbol of the Government of Canada

Office of Energy Efficiency Links

 

Business: Industrial

Menu

High-Performance Windows

Conventional Windows

Windows are a distinctive feature in any home. In most conventional houses, however, windows are the weak link in terms of energy efficiency and cold-weather comfort. During the winter, a typical window loses up to 10 times more heat than an equivalent area of an outside wall. Windows can account for up to 30 percent of the heat loss from a conventional home, adding significantly to heating costs. Drafts, window condensation and mould can also affect your comfort and your home’s indoor air quality.

R-2000 Windows

In R-2000 homes, high-performance windows solve these common problems. To keep overall heat loss within the strict R-2000 energy efficiency limits, builders pay close attention to how windows are selected and installed. The R-2000 Standard requires windows to meet minimum Canadian Standards Association Energy Rating (ER) values.

Windows are selected to meet the specific climate conditions that prevail at the house site – the colder the area, the more robust the window system. Builders try to place windows where they will gain the most solar heat during the winter, while ensuring that overhangs or other shading will prevent overheating during the summer. In many cases, the right windows can actually contribute more heat to the home during a sunny winter day than they lose at night.

Common Features

Glazing: R-2000 builders select windows with either two or three layers of glass, depending on the severity of the local climate. In most R-2000 homes, the glass also has a special low emissivity (low-e) coating to further reduce the heat loss.

Gas fills: Special inert gases, such as argon, fill the space between glass layers. These gases are poor heat conductors, so they reduce heat loss.

Insulating spacers: Many conventional windows use metal strips to separate glass layers, causing high heat loss around the edge of the glass and promoting window-edge condensation in the winter. Special insulating spacers, found in more energy-efficient windows, can prevent these problems and lead to significant energy savings.

Frames: The frame material can be as important to the performance of a window as the glass. R-2000 builders favour materials that offer high insulation value and low maintenance.

Window type: Casement and awning windows generally provide a tighter seal when closed than vertical or horizontal sliders. R-2000 builders favour window types that have been tested and proven to resist cold-weather air leaks.

Performance Requirements

Industry-wide standardized tests rate some windows for their energy efficiency. The resulting ER is a measure of the window's overall performance based on three factors:

  • solar heat gains
  • heat loss through frames, spacer and glass
  • heat loss through air leakage

Higher numbers indicate more energy-efficient windows. Most fixed (non-opening) windows have better ERs than operable (opening) windows.

The R-2000 Standard sets minimum ER requirements for windows, based on local climate conditions. Canada has many climatic regions, each with its own requirements for average heating degree-days. (The higher the number of heating degree-days, the colder the climate.)

R-2000 Standard Minimum ER Requirements for Windows
Selected Cities Heating Degree-Days Minimum Energy Rating
Operable Window1 Fixed Window2
Vancouver, Victoria up to 3500 –18 –10
Toronto, Calgary, Halifax 3501 to 6800 –13 –3
Thompson, Yellowknife, Whitehorse 6801 and over –10 0
  1. Windows that open or have fixed glazing with a sash
  2. Windows that have fixed glazing without a sash

R-2000 is an official mark of Natural Resources Canada.