RESNET Adopts Formal Interpretation on Definition of Conditioned Floor Area
by RESNET on JANUARY 25, 2011
The RESNET Board of Directors adopted a formal interpretation on the definition of Conditioned Floor Area (CFA) for rating a home. The interpretation was recommended by the RESNET Technical Committee.
The interpretation adopts the following definitions:
CFA includes all finished space that is within the (insulated) conditioned space boundary (that is, within the insulated envelope), regardless of HVAC configuration.
CFA includes unfinished spaces that are directly conditioned, that is, they have “fully ducted” intentional HVAC supply (or other intentional heat source).
CFA does not include spaces such as insulated basements or attics that are unfinished, if there is no intentional HVAC supply, or minimal supply (inadequate to be considered directly conditioned space.
CFA does not include heated garages.
The need for clarification on conditioned floor area and its various implications for conducting a HERS rating was long overdue. Because energy efficiency programs that refer to the RESNET standard may base incentives and/or compliance criteria on CFA, the raters needed guidance in order to consistently calculate CFA and apply it to the rating process.
To view the entire interpretation, go to http://www.resnet.us/standards/Floor_Area_Interpretation.pdf