Jun 1, 2018

Case Study: Field Test of Cold Climate Air Source Heat Pumps (Duplex)

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 a ccASHP installed in one unit of a recently completed St. Paul duplex.

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 maintaining a low cost electrically heated home. The heat pump was able to meet over 98% of the annual heating needs of the central system and the booster heater added the remaining 2%. The property owner was happy with the system performance and anticipates new solar panels drastically decrease or eliminate the mechanical heating costs for this home.

Learn more on the project page

Site Characterisitics 

  • Duplex built in 2016
  • Lower unit has the basement and 1st floor
  • 2,800 square feet finished area
  • Located in St. Paul, Minnesota
  • Two occupants