Commercial central air conditioners (CACs) and heat pumps (HPs) (<65,000 Btu/hr) are nearly identical to typical residential CACs and HPs, but are designed to operate on 3-phase electric current rather than single-phase power. Power supplied to residential buildings is almost always single phase, while most commercial buildings are wired with 3-phase power. Commercial 3-phase CACs and HPs can either be "single package" systems, where the evaporator coil and the condensing unit are combined into a single physical unit, or "split systems," where the condensing unit is typically placed outdoors while the evaporator is indoors.
The Energy Independence and Security Act (EISA) of 2007 required an increase in the cooling efficiency of 3-phase CACs and HPs (<65,000 Btu/hr) to 13 SEER (seasonal energy efficiency ratio) and an increase in the heating efficiency of 3-phase HPs to 7.7 HSPF (heating seasonal performance factor). These standards became effective June 16, 2008 and are identical to the current standards for residential CACs and HPs. SEER is the cooling output (in Btu) during a typical cooling season divided by total energy consumption (in watt-hours) during the same period. HSPF is the heat output (in Btu) over the heating season divided by total energy consumption (in watt-hours).
ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) Standard 90.1 is a commercial building energy code which all states must meet or exceed. ASHRAE Standard 90.1 includes minimum efficiency requirements for equipment, including 3-phase CACs and HPs. The Energy Policy and Conservation Act (EPCA) requires that if the equipment efficiency standards in ASHRAE Standard 90.1 are amended, DOE must either establish amended standards for the products at the levels specified in ASHRAE 90.1 or establish more stringent standards if they would result in significant additional energy savings and are technologically feasible and economically justified. In 2015, DOE updated the standards to align with ASHRAE 90.1-2013.
CACs and HPs are rated by their cooling capacity (in Btu/hr), which represents the amount of heat that an air conditioner or heat pump can remove from an enclosed space per hour. One “ton” of cooling capacity is equal to 12,000 Btu/hr. Technology options for improving the efficiency of 3-phase CACs and HPs include higher efficiency compressors, improved condenser and evaporator coils, and higher efficiency fan motors and fan blades.