Variable Refrigerant Flow Multi-Split Air Conditioners and Heat Pumps


Variable refrigerant flow multi-split ACs and heat pumps (VRFs) with cooling capacity of at least 65,000 Btu/h are a category of commercial air conditioners and heat pumps. These systems are configured as split systems that have at least three steps of capacity control on common, interconnecting piping (i.e. a single refrigerant circuit) and multiple indoor fan coil units.

VRFs are a category of ASHRAE equipment. 


The current standards for VRFs took effect on January 1, 2024. The standards were negotiated by manufacturers and efficiency advocates and are equivalent to the levels specified in the 2016 version of ASHRAE Standard 90.1. For the cooling efficiency levels, DOE translated the energy efficiency ratio (EER) levels in the 2016 version of 90.1 to the updated integrated energy efficiency ratio (IEER) metric.

In 2023, DOE issued a final determination not to amend standards for VRFs.

*The cooling energy efficiency metric, IEER, is a weighted calculation of mechanical cooling efficiencies at full-load (100%) and part-load (75%, 50%, and 25%) conditions. It is expressed in Btu/(Wh).

The heating energy efficiency metric, the heating coefficient of performance (COP), is a ratio of the heating capacity (watts) to the power input (watts) at 47 °F.


VRFs may be air-cooled or water-source. Some VRF systems are capable of providing simultaneous heating and cooling (‘heat recovery’ systems’). Single-phase VRFs less than 65,000 Btu/h are regulated as central air conditioners and heat pumps.


Federal Date States

Timeline reflects state standards from 2001 to present; federal standards from inception to present.