Building envelope: Windows and doors

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Save up to 30% on energy costs

picture of cold woman standing in front of single-pane window
picture of warm woman standing in front of double-pane window

The tale of two windows

Upgraded windows can make a significant difference to both the energy efficiency and comfort of your home. Replacing single-pane windows with thermal-pane can eliminate cold drafts and lower your energy use substantially.


Heat gained or lost through inefficient windows can increase the energy used to heat and cool your home by 25 to 30%.

Energy-efficient windows have:

  • special coatings (known as low emissivity coatings, or low-E glass) and insulated frames and sashes which will reduce the cold transfer from outside and condensation on the glass.
  • more glazing (panes of glass) for better exterior noise reduction and even more energy savings.
  • special inert gases between the glass panes rather than just air for better insulation.
  • a label on the product to indicate where the model is certified for use in Canada.

What to look for

  • A low U-value. The U-value is a measure of the window's insulation value. Look for windows in the range of 0.25 to 1.25, with 0.25 being the best.
  • Buy windows certified for installation in Canada. In Canada, all windows should be at least double-glazed – two panes of glass.
  • Windows with more glazing (panes of glass) and low-E glass are the most efficient.
  • Hinged windows (casements, awnings, hoppers, tilt-turns) are more air-tight than sliders.

Things to consider

  • Purchase ENERGY STAR® certified windows.
  • Windows that don't open are more energy-efficient, but floors with bedrooms require at least one window that opens for an emergency exit.
  • The window frame affects a window's insulation value, strength, maintenance and longevity. Wood, vinyl, fibreglass, and thermally broken metal frames are the most efficient.
  • Fiberglass and thermally broken metal frames have more strength than vinyl frames hence they can be narrower providing more glass area.
  • Hire trained installers to ensure your windows and skylights will perform their best.
  • Window and supplier warranties vary. Compare before you purchase.
  • Consider installing high insulation value windows on the east and north sides of your house to reduce heat loss.

Average cost

$300 to $700+ per window, plus installation.

Source: Natural Resources Canada


In addition to providing security, energy-efficient doors prevent air and temperature leak from the house. Doors come in a variety of materials, some of which reduce heat flow better than others. Depending on the style and type of insulation, for example, metal-clad doors can be more efficient than solid wooden doors. No matter what the material, ill-fitting doors lose energy and can make your home drafty and uncomfortable.

What to look for

  • Doors made of materials with high insulating values, such as fibreglass, vinyl, or steel.
  • Wood, vinyl or thermally broken metal frame.
  • Low air leakage rates (for pre-hung door systems).
  • Maintenance-free framing materials.
  • A high energy efficiency rating or a minimum of double glazing with a 12 mm (half-inch) or greater air space.

Things to consider

  • Make sure that windows, doors and skylights are ENERGY STAR® certified and hire a professional installer to ensure they perform their best.
  • Warranties differ from door supplier and type; compare before you purchase.

Average cost

$200 or more per door.

Source: Natural Resources Canada

Financial help available for windows and doors

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