Heat Pump Study

The Center for Energy and Environment (CEE) in Minnesota, a 501(c)(3) nonprofit organization, promotes approaches to energy efficiency that strengthen Minnesota’s economy and improve the environment. Over the course of two heating seasons (2015-2016; 2016-2017), the CEE conducted a field study of air-source heat pumps (ASHPs) to measure their capacity and effectiveness in cold weather and assess their potential to reduce reliance on fossil fuels.

Two of the homes used as test sites were equipped with split-ductless FH Series systems from Mitsubishi Electric Trane HVAC US (METUS). The CEE subsequently extended the field study to include an assessment of variable-capacity ducted air handlers that were unavailable at the launch of the study. As part of the field study extension conducted during the winter of 2017-2018, two homes were equipped with the PVA model from METUS. Three main factors were measured throughout the course of the study: sizing and modes of operation, performance in cold climates as well as impact and sustainability.

Key Takeaways from the Study:

  • INVERTER-driven cold climate ASHPs are capable of operating at very cold temperatures with inverter-driven compressors and modern refrigerant performing efficiently as rated.
  • Significant reduction in energy consumption was a function of a sizeable increase in the coefficient of performance (COP) compared to baseline systems.
  • Two homes with the FH series installed saw a 53%-56% reduction in both the cost and amount of electricity used. COP’s ranged from 4.0-4.5 during the shoulder season and between 1.0-1.5 during the coldest period. One split-ductless unit operated with a COP greater than 1.0 at -19°F.
Split-Ductless Elect. Resistance Metro 56%
Split-Ductless Elect. Resistance Northern MN 53%
  • ” Two homes with PVA installed resulted in 56% and 57% reduction in homeowner site heat energy BTU’s used. Compressors supplied 91% and 98% of the heating load without electric resistance boost. Annual COP’s were 1.82 and 1.85.
Ducted Gas Furnace Metro 56%
Ducted Elect. Resistance Metro 57%

The CEE report concludes that heat pumps can reduce reliance on less-efficient heating sources and fossil fuels. The report also notes how reliable, electric-powered ASHPs can contribute to a more sustainable built environment through fuel switching and beneficial electrification, a national movement to significantly reduce greenhouse emissions by replacing fossil fuels with electricity from clean renewable sources.

“CEE has field tested our cold climate air source heat pump products throughout Minnesota, and the results are impressive,” said Kevin DeMaster, manager, utility & efficiency programs, METUS. “The Cold Climate Air Source Heat Pump report validated our single-zone ductless equipment to displace load in northern Minnesota homes. This first study led to two case studies of our ducted air handler (PVA) as a whole home solution in two chilly Minneapolis applications in 2018. While we have long known that our products perform reliably in cold weather, these published independent studies outline parameters and comparison tables proving cold climate performance and energy savings.”

To learn more, please read the full report on the CEE site or watch the CEE webinar Air Source Heat Pumps: Cost-Effective & Cold-Climate Ready.