Jun 1, 2018

Case Study: Field Test of Cold Climate Air Source Heat Pumps (Single-Family)

Project Background

This field study is an extension of the recently completed CARD field study of flex fuel and ductless cold climate air source heat pumps (ccASHP) in six homes. Research staff monitored a new-to-the-market ccASHP that was not available at the launch of the CARD study. This system was installed in two occupied Minnesota homes. The ccASHP systems were provided by Mitsubishi Electric Cooling & Heating and installed by a licensed contractor. This case study reports on the results of an installation in a singlefamily Minneapolis home. The ccASHP replaced an existing forced air furnace and split system air conditioner.

Investigation

The project team installed detailed monitoring equipment to determine installed performance of the cold climate air source heat pump. Data was gathered at a one-second resolution and downloaded daily via a cellular modem connection. The instrumentation allowed for measurement of system temperatures, component runtime, energy consumption, energy delivery, and real-time coefficient of performance (COP).

Findings

Detailed data was measured during the winter of 2017/2018 and used for the analysis to characterize the performance of the system. Generally the system met expectations, both in terms of the performance as well as homeowner satisfaction. The site saw an energy reduction of over 50% and the installation of an all-electric heat pump helped achieve the homeowner’s goal of switching to an all-electric home. The heat pump was able to meet over 90% of the annual heating load and the booster heater added the remaining. However, the homeowner’s operational cost increased compared to their previous natural gas furnace. The all-electric heating pump would require an electric rate of $0.065 per kWhr to achieve the same operational costs as a natural gas condensing furnace. Although not significant for this analysis, the homeowner is excited to add solar panels to the home, which should drastically decrease or eliminate the cost to run the cold climate air source heat pump.

Learn more on the project page.

Site Characterisitics 

  • Two-bedroom, one bath, 1.5 story single-family home
  • Bungalow built in 1924
  • 1,600 square feet
  • Located in Minneapolis, Minnesota
  • Two occupants
  • 26,000 Btu/hr measured heating load at -11⁰F