Measuring Performance: Condensation Resistance

CR measures how well a window resists the formation of condensation on the inside surface. CR is expressed as a number between 1 and 100. The rating value is based on interior surface temperatures at 30%, 50%, and 70% indoor relative humidity for a given outside air temperature of 0° Fahrenheit under 15 mph wind conditions. The higher the number, the better a product is able to resist condensation. CR is meant to compare products and their potential for condensation formation. CR is an optional rating on the NFRC label.

Both the National Fenestration Rating Council (NFRC) and the American Architectural Manufacturers Association (AAMA) have developed systems for rating the condensation resistance of fenestration products. AAMA 1503-09, Voluntary Test Method for Thermal Transmittance and Condensation Resistance of Windows, Doors and Glazed Wall Sections gives a dimensionless rating titled, Condensation Resistance Factor (CRF). This number ranges from 0 to 100; the higher the number the better a product resists forming condensation. AAMA provides the Condensation Resistance Factor Toolexit disclaimer to provide general guidance on suggesting a minimum CRF based on a project-specific set of environmental conditions. Obtaining a CRF for a window system, a physical test must be performed.

NFRC 500-2010, Procedure for Determining Fenestration Product Condensation Resistance Valuesexit disclaimer determines Condensation Resistance (CR) is expressed as a number between 1 and 100 is based on computer simulations