VRF, which stands for Variable Refrigerant Flow, is making a big splash in the United States after having been invented and used in Asia decades ago. Heat pump technology in the United States is well established, saving as much as 40 percent in electricity bills over traditional electric resistance heating systems, according to the U.S. Department of Energy. Buildings in the U.S. can reduce energy consumption by an additional 40 percent over that in many climates. Oregon State’s Pacific University chose VRF systems for two recently completed 60,000-square-foot student housing projects, Gilbert and Burlingham Halls, and could not be more pleased with the results. While the average Energy Use Index for residence halls in the Northwest U.S. is 80 kbtu per-square-foot per year, both of the newly built Pacific University Halls have consistently performed at an EUI of 46 kbtu per-square-foot per year. Similar results have been achieved for like projects across the country.
Unlike a boiler or a furnace, heat pumps do not make heat, they transfer heat by circulating a refrigerant through a cycle of evaporation and condensation. A compressor pumps the refrigerant between two heat exchanger coils—one for evaporation and one for condensation. In the evaporative coil, the refrigerant absorbs heat as it is evaporated, and at the condensing coil the refrigerant releases the heat that it absorbed during evaporation. The cycle can be reversed to provide cooling as well, offering both heating in the winter and air conditioning in the summer using the same process in the same closed loop system.