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Windows and Doors

How do I ensure that my new windows will perform well?

In addition to choosing high quality windows and looking for ENERGY STAR® certified windows, follow these steps to ensure optimal performance of your windows:

  • Consult with experts: Ask your contractor how your new windows will perform in your home. Be sure to ask about Solar Heat Gain and the potential for overheating. For more information see Why is it important to select the right windows for my home?
  • Hire professional installers: The quality of the installation can have an enormous effect on window performance and home comfort. Hire experienced and professional contractors to ensure that the company you select provides the best possible installation and the right type of window for your home.
  • Maintain your windows: Similar to servicing a vehicle, preventive maintenance is a good investment to minimize future problems. Undertake a thorough inspection of all window components (glass, frames and seals) every season looking for any signs of damage or condensation. Keep windows and surrounding wall areas clean. Consult the owner’s manual and ask the installer for details.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

Why is it important to select the right windows for my home?

When selecting windows for your home, it is important to consider how different glazing options will affect both the energy performance and thermal comfort of your home. A window’s ability to block or admit incoming solar energy is measured by its solar heat gain coefficient (SHGC). Solar gain from windows can be to the benefit or detriment of a home’s comfort depending on factors such as climate, window orientation, and the amount of window shade/ cover. In colder climates, high solar gain can be beneficial and reduce the heating load for your home, whereas in a warm climate, high solar gain can cause overheating.

Overheating caused by solar gain from windows can lead to decreased comfort and an increased energy demand on your cooling systems. To avoid this problem, windows facing south, west and east, susceptible to high solar heat gain may benefit from low-SHGC windows. Windows facing north or that have significant shade/ cover, and have minimal sun exposure may benefit from high-SHGC windows.

Talk to your window installer to help choose the best windows for the comfort of your home.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

How do I interpret the U-factor and performance of windows?

U-factor is a measure (W/ m2·K) of the rate of non-solar heat transfer through the window. The lower the U-factor, the greater a window’s resistance to heat flow, the better its insulating value, and the more energy efficient it is.

Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight. SHGC is measured on a scale of 0 to 1, with values typically ranging from 0.25 to 0.80. The lower the SHGC, the less solar heat the window transmits.

Visual Transmittance (VT) measures the amount of light the window lets through. VT is measured on a scale of 0 to 1, with values generally ranging from 0.20 to 0.80. The higher the VT, the more light you see.

See our glossary for more energy efficiency terms.

What are ENERGY STAR windows?

Beautiful and practical, ENERGY STAR® certified windows can increase the energy efficiency of your home and save you money on utility bills. They also reduce condensation, decrease outside noise, protect furniture from sun damage, and can provide increased temperature regulation during summer and winter (for more information, see why is it important to select the right windows for my home?).

The following advances in technology mean that energy-efficient windows are more efficient than ever:

  • Low-emissivity (low-E) coating reduces the ability of heat to pass through them preventing heat from escaping your home in the winter and keeping cooler air in your home in the summer.
  • Double or triple glazing improves efficiency while reducing exterior noise.
  • Inert argon gas between the window panes prevents heat transfer and minimizes condensation.
  • Insulated spacers and frames also prevent heat loss.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

What are the benefits of ENERGY STAR windows?

  • Increased comfort: Selecting the appropriate windows can improve temperature regulation and heat retention in the home, keeping you cooler in the summer and warmer in the winter.
  • Peace and Quiet: Double (or triple) pane windows better insulate your home from exterior noise.
  • Protect your interior: Furniture, flooring and art is better protected from harmful UV radiation.
  • Increased home value: Efficient, high quality windows improve the aesthetics and increase the value of your home.
  • Save energy and money: Lower utility bills through energy savings.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

What are the costs of ENERGY STAR windows?

ENERGY STAR® certified windows typically cost more than standard windows because of their higher level of energy performance. Prices vary greatly based on the number of windows required, size, type, material, warranty, quality of installation and manufacturer. Installing energy efficient windows can help to reduce energy costs and increase the resale value of your home.  If you are installing new windows use our rebate search tool to check if there are rebates to help reduce your costs.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

What are these labels that I have on my windows?

If you have ENERGY STAR® certified windows, they should come with an ENERGY STAR  label that highlights important performance features of the window, including:

  • Its certified performance ratings (U-factor, Solar Heat Gain Coefficient, Energy Rating, and Visual Transmittance)
  • The climate zone(s) for which it is certified
  • A description of the product (type, materials, glazing, etc.)
  • Its certification information

For more information about ENERGY STAR certified windows, visit Natural Resources Canada.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

My new windows didn’t come with ENERGY STAR labels, do they qualify for rebate programs?

For rebate programs that require ENERGY STAR® windows as an eligibility requirement, your new windows must have ENERGY STAR labels in order to qualify. If your new windows arrive without an ENERGY STAR label or other documentation confirming ENERGY STAR qualification, then it is not certified with the program’s high efficiency standards.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

My new windows are ENERGY STAR certified in the United States; are they also certified for my climate zone in Canada?

This will depend on whether the window manufacturer has the same model certified in Canada. Some ENERGY STAR® windows have a label that displays a climate zone map of both Canada and the USA. If the shaded area of the map overlays the region where you live, the windows are certified in your climate zone. If an ENERGY STAR label only shows that the window is certified in the United States, the product is likely not ENERGY STAR certified in Canada.

Since Canada and the United States have different climate zones, specific models should be looked up in the Natural Resources Canada fenestration database to determine whether the product is certified for your climate zone. In the database you can enter the product’s model number or Energy Efficiency Verification Reference number from the energy performance label.

Refer to the sample label below, and visit Natural Resources Canada for more information about ENERGY STAR windows.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

How do I know if my new windows are ENERGY STAR certified for my climate zone?

All ENERGY STAR® certified windows will come with an ENERGY STAR label. The ENERGY STAR label will include a climate zone map of Canada and indicate which climate zone the window model is certified for.

Refer to the sample label below, and visit Natural Resources Canada for more information about ENERGY STAR windows.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

Should my windows have an ENERGY STAR label?

If your new windows arrive without an ENERGY STAR® label or other documentation confirming ENERGY STAR qualification, then they are not certified with the program’s high efficiency standards.

According to Natural Resources Canada, fenestration products can be ENERGY STAR certified if they have met one or both of the following criteria:

  • A high Energy Rating (ER) — The ER is a formula that includes the U-factor, air leakage and solar heat gain.  The higher the ER value, the more energy efficient the product (ER ratings do not apply to skylights). Keep in mind that ENERGY STAR certified windows with a high Solar Heat Gain Coefficient may not be the most efficient option for all windows you are looking to replace. See our FAQ on why is it important to select the right windows for my home?
  • A low U-factor — U-factor measures the rate of heat transfer. The lower the U-factor, the better the product insulates.
    Please note that the energy efficiency ratings used to determine ENERGY STAR certification take into account the energy efficiency of the entire product. If you only look at the energy efficiency ratings of the glass portion of the window, a product can seem more energy efficient than it actually is.

For more information about the rating criteria for ENERGY STAR certified windows, visit Natural Resources Canada.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

I have a heritage home, should I install new windows or storm windows for my original windows?

One of the defining aspects of a heritage home’s character can be its windows. If you want to increase the energy efficiency of your home and preserve its heritage aesthetic, considering fixing existing windows and/or installing storm windows. If original wooden storm windows have been destroyed, you can install custom storm windows made to order. The benefits of installing wood storm windows include improved thermal efficiency, moisture transfer, and compatibility with traditional wood-frame house construction. Avoid metal storm windows and storm-and-screen combinations if you want to preserve the appearance of your heritage home. Interior storm windows are less noticeable and easier to maintain than exterior storm windows.

Did you see a building science or energy efficiency term you did not understand? Check out our glossary.

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