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Windows, Doors and Skylights

Qualifying Criteria

For ENERGY STAR^®, windows and doors are qualified for their energy efficiency by either a U-value or Energy Rating (ER) for each of the four Canadian zones. Skylights are qualified by their U-value only. The energy efficiency values were developed primarily for low-rise (three floors or fewer) residential dwellings.

U-value

A U-value indicates the rate of heat transfer. The lower the U-value number, the slower it transfers heat from a warm area to a cold area. Equivalent R-Values have been given to help you understand the U-values. An R-Value is the inverse of a U-value and indicates the resistance to heat transfer. The higher the R-Value number, the more insulative the product is. The R-Values given are in imperial units. Neither the U- or R-value account for heat energy from the sun (solar gain).

Energy Rating

The Energy Rating (ER) value is calculated using a formula that balances a product's U-value with its potential solar heat gain coefficient (SHGC) and airtightness.

The following tables show the levels for each zone in Canada. The ratings given in the tables are for the entire product. Energy efficiency ratings for the glass portion only, often called "centre-of-glass" ratings, usually make the product appear more energy efficient than it really is.

ENERGY STAR Requirements for Windows and Doors

(Products may comply based on either their U-value and R-Value or their Energy Rating.)

*The methodology used to calculate Energy Ratings, as defined by the Canadian Standard Association, was recently changed. Under the new 2004 standard, all windows and doors have positive ER numbers.

ENERGY STAR Requirements for Skylights

Airtightness and Other Ratings

All windows and sliding glass doors must be rated for their airtightness, watertightness, wind load strength, resistance to forced entry, insect screen strength (windows only) and ease of operation (sliding glass doors only) when they are installed in new homes or buildings. Provincial and local building codes require different airtightness, watertightness and wind load strength categories depending on the climatic conditions.

All ENERGY STAR qualified sliding glass doors and operable windows must have at least an A2 for airtightness. Picture windows must receive a “Fixed” rating. The following table shows the range for each product type.

Airtightness Categories – Windows and Sliding Glass Doors

*The operable and non-operable sashes may be tested and rated separately for single-hung and single sliding windows.

There are no minimum requirements for ENERGY STAR for the other categories. The following table shows the ranges for each product type.

Other Categories – Windows

*This test measures only how well the screen mesh stays fastened to the screen mesh frame, not how well the insect screen stays fastened to the window frame. Most insect screens are designed to be easily removable from the window to allow for egress in case of an emergency. An S1 rating is normally adequate for residential applications.

Other Categories – Sliding Glass Doors

Note: Insect screen strength, resistance to forced entry and ease of operation ratings are not available in the ENERGY STAR qualified model listings.