Additional ENERGY STAR®
Product Categories in Canada

Qualified 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 less) residential dwellings.


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 gain solar heat gain coefficient (SHGC). The SHGC is a measure of solar heat gain and air-tightness.

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 Effective October 1, 2010
(Products may comply based on either their U-value and R-value or their Energy Rating)

Zone Heating
Compliance Paths
Energy Rating (ER) or U-Factor
Minimum ER (unitless)
Maximum U-Factor 2.00
(0.35 Btu/h•ft.²•°F)
Minimum ER
A <= 3500 21 or 1.80 (0.32) 13
B > 3500 to <= 5500 25 or 1.60 (0.28) 17
C > 5500 to <= 8000 29 or 1.40 (0.25) 21
D > 8000 34 or 1.20 (0.21) 25

Zone Heating
Compliance Paths
Energy Rating (ER) or U-Factor
Minimum ER (unitless)
Maximum U-Factor 2.00
(0.35 Btu/h•ft.²•°F)
Minimum ER
A <= 3500 21 or 1.80 (0.32) N/A
B > 3500 to <= 5500 25 or 1.60 (0.28) N/A
C > 5500 to <= 8000 29 or 1.40 (0.25) N/A
D > 8000 34 or 1.20 (0.21) N/A

ENERGY STAR Requirements for Skylights Effective October 1, 2010

Zone Heating Degree-
Day Range
Maximum U-Factor
W/m²•K (Btu/h•ft.²•°F)
A <= 3500 2.80 (0.50)
B > 3500 to <= 5500 2.60 (0.46)
C > 5500 to <= 8000 2.40 (0.42)
D > 8000 2.20 (0.39)

*includes Tubular Skylights

U-Factor Conversion to R-Value

Windows, doors and skylights are not normally assigned an R-value when tested. To help you better understand their insulating performance, sample U-factors in both metric and imperial units have been converted to R-values in the table below. Because Energy Rating values are derived from a formula that uses both U-factor and solar heat gain, there is no method to directly convert the Energy Rating value to R-value.

U-Factor Conversion to R-Value
3.40 0.60 1.7
3.20 0.56 1.8
3.00 0.53 1.9
2.80 0.50 2.0
2.60 0.46 2.2
2.40 0.42 2.4
2.20 0.39 2.6
2.00 0.35 2.9
1.80 0.32 3.2
1.60 0.28 3.6
1.40 0.25 4.0
1.20 0.21 4.8
1.00 0.18 5.6
0.80 0.14 7.1
0.60 0.11 9.1

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

Type Least Airtight Most Airtight
Most Operable Windows A1 A3
Single-Hung Windows* A1/Fixed A3/Fixed
Single Sliding Windows* A1/Fixed A3/Fixed
Non-Operable (Fixed)
Casement Windows
A1 A3
Picture Windows Fixed (pass/fail rating)
Sliding Glass Doors A1 A3
*The operable and non-operable sashes may be tested and rated separately for single-hung and single sliding windows.

Other Categories – Windows

Test Lowest Category Highest Category
Watertightness B1 B7
Wind Load Strength C1 C5
Insect Screen Strength* S1 S2
Resistance to Forced Entry F10 or F1 F20 or F2
*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

Test Lowest Category Highest Category
Watertightness B1 B4
Wind Load Strength C1 C3
Ease of Operation E1 E3
Resistance to Forced Entry F1 F2

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

Key features
More about the climate zones
Sample labels for manufacturers

Energy Efficiency Ratings:
List of models: Windows
List of models: Sliding glass doors
List of models: Entry doors, sidelights and transoms
List of models: Skylights

Participating Window and Door Dealers
Participating Window and Door Manufacturers
Technical Specifications for Manufacturers  | PDF
How to Participate

The ENERGY STAR name and the ENERGY STAR symbol are registered trademarks of the United States Environmental Protection Agency and are used with permission.