Standard: NFRC 500 – Procedure for Determining Fenestration Product Condensation Resistance Values

Scope: This test applicable to both residential and commercial fenestration products.

Applicable Products: Windows, Doors, Skylights, Curtain Walls

Test Procedure: This procedure utilizes computer simulation software to determine overall product condensation resistance. Two-dimensional finite element software is used to calculate the surface temperatures of individual elements of the window. Frame, Edge and Center-of-Glass temperatures are calculated using the WINDOW and THERM software programs developed by Lawrence Berkeley National Laboratory (LBNL). These temperatures are used to calculate the potential for condensation at several humidity levels and those results are combined into a single value for rating purposes.

The NFRC 500 procedure calculates a rating for winter conditions of 70ºF (21ºC) interior temperature and 0ºF (-18ºC) exterior temperature, using relative humidity of 30%, 50% and 70%.

The ANSI/NFRC 100 procedure calculates U-Factors for winter conditions of 70ºF (21ºC) interior temperature and 0ºF (-18ºC) exterior temperature.

End Result: A Condensation Rating (CR) is determined. The CR can be used to compare the relative performance of different products. This is almost always done in conjunction with ANSI/NFRC 100 testing for U-Factor.

Special Notes: There are several methods for rating and/or determining condensation performance. They are not equivalent and in most cases cannot be correlated. Alternative ratings can be determined using AAMA 1503 (Condensation Resistance Factor, CRF) and CAN/CSA-A440.2 (Temperature Index, I). Condensation performance can also be evaluated specifically for projects using custom computer simulation, custom hot box testing, and/or large scale mock-up condensation evaluations. The specific needs should be considered prior to selection of a method.


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