Heat Pumps and Electrification
Summary
Heat pumps move heat instead of making it, so they deliver more heating energy than the electricity they use. Efficiency ratings at rated conditions do not show low-temperature performance, so cold-climate projects should check capacity and efficiency at 5 F.
Cols
Terminology
- COP (coefficient of performance): instantaneous heat delivered divided by electricity used; dimensionless
- HSPF2: heating-season ratio of heat delivered to electricity consumed
- SEER2: cooling-season equivalent
- Cold-climate heat pump: unit meeting ENERGY STAR low-temperature criteria
Standards
- ENERGY STAR cold-climate test: COP of at least 1.75 at 5 F, and at least 70 percent of 47 F heating capacity available at 5 F
- Cold-climate thresholds for ducted split and single-package units: at least 8.1 HSPF2 and 15.2 SEER2
- Non-ducted split units: at least 8.5 HSPF2
- SEER2 says nothing about low-temperature heating
Selection
- Check rated capacity and COP at the project design temperature, not only seasonal ratings
- Check current ENERGY STAR product specifications before relying on any tier figure
Sources
- ENERGY STAR: air source heat pump key product criteria, https://www.energystar.gov/products/air_source_heat_pumps/key-product-criteria
- ENERGY STAR: heat pump product page, https://www.energystar.gov/node/5805
- Wikimedia Commons: Carrier Outdoor Split Air Conditioner Heat Pump System (55005181522).jpg, by Tony Webster (CC BY 4.0), https://commons.wikimedia.org/wiki/File:Carrier_Outdoor_Split_Air_Conditioner_Heat_Pump_System_(55005181522).jpg