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Title: Field Performance of Inverter-Driven Heat Pumps in Cold Climates

Traditionally, air-source heat pumps (ASHPs) have been used more often in warmer climates; however, some new ASHPs are gaining ground in colder areas. These systems operate at subzero (Fahrenheit) temperatures and many do not include backup electric resistance elements. There are still uncertainties, however, about capacity and efficiency in cold weather. Also, questions such as “how cold is too cold?” do not have clear answers. These uncertainties could lead to skepticism among homeowners; poor energy savings estimates; suboptimal system selection by heating, ventilating, and air-conditioning contractors; and inconsistent energy modeling. In an effort to better understand and characterize the heating performance of these units in cold climates, the U.S. Department of Energy Building America team, Consortium for Advanced Residential Buildings (CARB), monitored seven inverter-driven, ductless ASHPs across the Northeast. Operating data were collected for three Mitsubishi FE18 units, three Mitsubishi FE12 units, and one Fujitsu 15RLS2 unit. The intent of this research was to assess heat output, electricity consumption, and coefficients of performance (COPs) at various temperatures and load conditions. This assessment was accomplished with long- and short-term tests that measured power consumption; supply, return, and outdoor air temperatures; and airflow through the indoor fan coil.
 [1] ;  [1]
  1. Consortium of Advanced Residential Buildings, Norwalk, CT (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
NREL/SR--5500-63913; DOE/GO--102015-4642
DOE Contract Number:
AC36-08GO28308; KNDJ-0-40342-05
Resource Type:
Technical Report
Resource Relation:
Related Information: Work performed by Consortium for Advanced Residential Buildings (CARB), Norwalk, Connecticut
Research Org:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
Country of Publication:
United States
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION Residential; Residential Buildings; CARB; Building America; inverter-driven; air-source heat pumps; Steven Winter Associates, Inc.; Consortium for Advanced Residential Buildings; SWA; COPs; cold climate; Northeast; performance; heating; air flow measurement; heat pump; ASHP