SPOTLIGHT:
Annual Energy Performance Subcommittee

History
The Annual Energy Performance Subcommittee (AEP) is one of NFRC’s original subcommittees, dating back to 1989 when NFRC began. NFRC’s founding members realized there was a need for a reliable annual energy performance rating for windows, because many consumers were not sure how to choose the most energy-efficient windows for their homes and because the terms U-factor and solar heat gain coefficient were not well known.

In August of this year, NFRC 901 was published and is now available for use. The document, “Guidelines to Estimate the Effects of Fenestration on Heating and Cooling Energy Consumption in Single Family Residences,” offers a standard procedure for calculating and comparing the heating and cooling energy performance of different windows in a specific home.

Leadership
Tom Culp of Birch Point Consulting serves as the subcommittee chair and Jim Larsen of Cardinal Glass Industries, Inc. is the vice chair. Scott Hanlon is the NFRC staff liaison.

Scope
AEP is responsible for developing the procedures to rate the annual energy performance of fenestration products and fenestration products attachments in homes. It takes into account the variability of housing characteristics.

Status
While NFRC 901 gives consumers an invaluable tool for choosing energy-efficient windows, the AEP cautions that estimated energy consumption is only one of the many parameters that should be considered in selecting a fenestration product. For instance, the estimated energy consumption analysis does not consider other issues such as comfort, durability, visible light transmission, or condensation.

Next Steps
The subcommittee is working on refining a procedure that will estimate the effects of fenestration on energy use in a generic reference house with a general set of assumption that represent a broad average of lifestyles.

Developing the reference house criteria is part of the reason it took so long to for the NFRC to publish the NFRC 901. The challenge was not finding how to calculate the energy performance in a specific home, but how to do it for a “typical reference home” which would give a fair comparison of different products while still capturing the wide variability of home types across the country. This type of procedure would enhance the effectiveness of NFRC 901.