Answer:
CFA, or Conditioned Floor Area , is the legal definition of the total floor area (in square feet) of the enclosed temperature conditioned space on all floors of a building. It's measured at each floor level to the outside face of the building's insulated envelope (typically the outside face of studs). It's the most widely adopted term utilized by building officials throughout North America to quantify the scope of the heating requirements of a building. For this reason, we use CFA as the basis for our system pricing because CFA is the single number that correlates most closely with the cost of the materials and engineering required to heat a home of a particular size.