NAFS – 08

North American Fenestration Standard (NAFS), often referred to as a Harmonized Standard came into effect for Windows and Doors installed beginning December 20th 2013 in British Columbia.Windows and doors must be tested and rated for conformance to NAFS 08 and the Canadian Supplement to meet the 2012 BC Building Code for all new construction and renovations that require a permit. NAFS is an improved method of classifying the type, class and performance of Windows and Doors over previous standards, greater product testing is needed to achieve these standards so all manufactures are required to re-test their products to show they comply. Unlike past standards NAFS does not have a single minimum rating but is tied to geographic location and conditions, it also provides a standardized methodology for rating the entire mulled assembly with the overall performance only being as high as the weakest part of the assembly. NAFS levels the playing field when comparing products forcing everyone up to meet the same standards. The classifications are Performance Class, Performance Grade and Gateway Performance.

Performance Class

There are four Performance Classes: R: Light duty, commonly used in single-family dwellings. (Part 9 Buildings) – Minimum requirement. LC: Medium duty, commonly used in low-rise and mid-rise multifamily dwellings. (Part 9 Buildings) CW: Heavy duty, commonly used in low to mid-rise multifamily dwellings where limits on deflections are imposed and tougher environmental constraints exist. (Part 9 Buildings) AW: Severe duty, used in high-rises or when extreme use of fenestration is expected. (Part 5 Buildings)

Performance Grade

The Performance Grade is a single numeric designation based on Design Pressure (DP) but representing a number of performance attributes:
  • Uniform load tests (DP)
  • Air and Water penetration resistance
  • Operability
  • Forced Entry
  • Fabrication Quality
  • Stiffness and stress tests
  • Hardware load tests
  • Other tests, such as durability and life-cycle test
The Performance Grade is determined by geographic location, building height, terrain conditions and serviceability. The following link will connect you to the performance calculator from Fenestration Canada that will help you determine your Performance Grade needs: http://www.fenestrationcanada.ca/calculator

Gateway Requirements

Each Performance Class (R, LC, CW and AW) has a defined “gateway” set of requirements, these are the minimum test sizes and pressures that each product must meet to qualify for a Performance Class.


For every Window, Door or combination that has been tested to meet NAFS the manufacturer must affix one temporary NAFS label showing the Class and size of window tested and the rating for the lowest rated window in the combination. In addition a permanent label identifying compliance to the NAFS code needs to be applied to the window or door.  

Rating criteria and standards—windows, doors and skylights

How is your fenestration product measured?


Rating for energy performance

In Canada, the energy performance of windows, doors and skylights is tested using the Canadian Standards Association (CSA) A440.2 standard. (Some products sold in Canada may also be tested using the standards of the National Fenestration Rating Council in the United States.) In Canada, energy performance is rated using the following values:
  • U-factor—the rate of heat transfer from warm to cold areas in watts per square metre Kelvin (W/m2K) or in British thermal units per hour per square foot Fahrenheit (Btu/h x sq. ft. x °F). In either case, the lower the number, the more efficient the product.
  • Solar heat gain coefficient (SHGC)—a ratio showing the amount of the sun’s heat that can pass through the product. The higher the number, the more solar heat the product gains.
  • Energy Rating (ER)—a value demonstrating the balance between U-factor, SHGC and air leakage. The higher the number, the more efficient the product. (This value applies to windows and doors only.)
  • R-value—a value indicating the resistance to heat transfer in square feet per hour in degrees Fahrenheit per British thermal unit (sq. ft. x h x °F/Btu). The higher the number, the more efficient the product.(The R-value is not part of the energy performance standards, but is often quoted by contractors and sales staff as a measure of performance.)
  • Visible transmittance (VT)—a ratio of the amount of visible light that can pass through a product. The higher the number, the more light can pass through.
  • Centre-of-glass rating—an energy-efficiency value that refers only to the glass portion of a product and not the product as a whole.

Rating for physical performance

Canadian building codes require that all windows and doors be rated for their physical performance before being installed in new homes or buildings. Minimum air leakage, water tightness and structural strength ratings vary between provinces, territories and municipalities, depending on climate conditions. Canadian standards are being brought in line with the harmonized North American Fenestration Standard (NAFS) that applies to all windows, doors and skylights in Canada and the United States. Under this standard, products are assigned a performance grade based on where they are used:
  • R—single-family residential buildings
  • LC—low- and mid-rise multi-family residential and light commercial buildings
  • CW—mid-rise multifamily residential and commercial office buildings
  • AW—high-rise multifamily residential and commercial office buildings
Each product is also given a number. The higher the number, the stronger and more water-resistant the product is.


When you buy certified windows, doors and skylights, you can be sure that they have been tested against current standards by an accredited laboratory, and that those test results have been verified by an independent third party. Richmond Building Supplies has submitted a selection of exterior doors that have been certified for energy performance by this accredited agency: Some insulated glass (IG) units also carry Insulating Glass Manufacturers Alliance (IGMA) certification. The IGMA program certifies that a manufacturer can consistently build IG units that will not fog and whose seals will not fail prematurely.  
Source: Natural Resources Canada Date Modified: