Cold climate VRF systems

December 20, 2018 by Scott Hackel and Scott Schuetter

Application of air source variable refrigerant flow (VRF) in cold climates

Variable refrigerant flow (VRF) systems use variable speed, split heat pumps to provide space heating and cooling to a building's conditioned areas. Air source VRF systems perform best in moderate climates, as they typically lose capacity and efficiency at low ambient temperatures—or moderately low wet bulb temperatures where defrost is required—and may be supplemented by an additional heat source.

In colder climates, this often necessitates the addition of a supplementary heater within a partially-enclosed mechanical room housing the outdoor units. Because of their lower capital cost as compared to water or ground source alternatives, the majority of VRF systems being implemented in cold climates today are air source. However, significant questions remain regarding how to design and operate air source systems at low outside air temperatures.

An Illustration of a VRF application in cold climates

An infographic demonstrating VRF systems
VRF can be made practical in cold climates using a supplemental heating source.


This project was made possible with significant funding from Daikin North America, LLC. Masters Building Solutions also provided technical input. The project would not have been possible without these two organizations’ assistance. Former Slipstream staffer Alisa Petersen also contributed to this project.