Efficiency
HSPF2
A seasonal heating-efficiency rating for air-source heat pumps.
What is HSPF2?
HSPF2 stands for Heating Seasonal Performance Factor 2. It expresses the seasonal heating efficiency of covered heat pumps under the updated DOE test procedure. The rating compares standardized seasonal heating output in BTU with the electrical energy consumed in watt-hours.
HSPF2 is the updated rating associated with the newer DOE test procedure, replacing the older HSPF representation for newly rated covered equipment.
A higher HSPF2 generally represents greater standardized seasonal heating efficiency. Actual cold-weather performance can still vary substantially with outdoor temperature, equipment controls, defrost operation, auxiliary heat, installation, and system sizing.
Why it matters
For heat pumps, cooling efficiency is only half of the story. HSPF2 helps compare seasonal heating performance, especially when a system will provide a meaningful share of a building's winter heat.
Formula / Conversion
HSPF2 = seasonal heating output (Btu) ÷ seasonal electrical energy input (Wh)
Sources
HVACBird prioritizes government standards bodies, federal test procedures, and recognized HVAC certification organizations for technical definitions.
Electronic Code of Federal Regulations
Federal test-procedure requirements for central air conditioners and heat pumps, including SEER2, EER2, and HSPF2.
U.S. Department of Energy
DOE guidance explaining SEER2 and HSPF2 ratings and the 2023 testing transition.
Related HVAC Terms
SEER2
A seasonal cooling-efficiency rating used for central air conditioners and heat pumps.
EER2
A cooling-efficiency rating measured at a specified full-load test condition.
COP
A dimensionless ratio comparing useful heating or cooling delivered with the work supplied to the system.
Heat Pump
Heating and cooling equipment that uses a refrigeration cycle to move heat between locations.
Matched System
A specific combination of HVAC components evaluated together as one system.