Rating System

Performance GradesFor the 2008 and 2011 editions of NAFS, the 4 Performance Grades are:

  • R––15 psf (720 Pa) for R class (commonly used in one- and two family dwellings)
  • LC––25 psf (1,200 Pa) for LC class (commonly used for low- and mid-rise multifamily dwellings and other buildings where larger sizes and higher loading requirements are expected)
  • CW––30 psf (1,440 Pa) for CW class (commonly used in low and mid-rise buildings where larger sizes, higher loading requirements, limits on deflection and heavier use are expected)
  • AW––40 psf (1,920 Pa) for the AW class (commonly used in high rise and mid-rise buildings to meet increased loading requirements and limits on deflection and in buildings where frequent and extreme use of the fenestration products is expected)
To qualify for a given performance grade (PG), a representative specimen of the product must pass all required performance tests for the following, in addition to all required auxiliary (durability) tests for the applicable product type and desired performance class:
  • Operating force (if applicable)
  • Air leakage resistance
  • Water penetration resistance
  • Uniform load deflection test
  • Uniform load structural test
  • Forced-entry resistance (if applicable)

 

MPH to PSF Conversion Chart
The charts to convert positive and negative pressures to comparable wind speeds.
MPH PSF   MPH PSF   MPH PSF
5 0.06 60 9.22 115 33.86
10 0.26 65 10.82 120 36.86
15 0.58 70 12.54 125 40.00
20 1.02 75 14.40 130 43.26
25 1.60 80 16.38 140 50.18
30 2.30 85 18.50 150 57.60
35 3.14 90 20.74 160 65.54
40 4.10 95 23.10 170 73.98
45 5.18 100 25.60 180 82.94
50 6.40 105 28.22 190 92.42
55 7.74 110 30.98 200 102.40

Performance RequirementsAir Infiltration

Test procedures, such as ASTM E283-04 Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen, are used widely in the industry to account for product design, and to some extent, quality control.

Generally, operable products with an infiltration rate of less than 0.3 cfm/square foot are required. Architectural grade products utilizing a compression seal are required to have an infiltration rate of less than 0.1 cfm/square foot. Non-operable products are not expected to have a measurable level of infiltration.
Source: AAMA and Efficient Windows Collaborative