Ductless Heat Pumps: Applications for Northern California & Low Energy Homes


Homes on the path to deep energy reductions need space conditioning systems that can efficiently meet reduced loads as the building is improved. Most conventional systems are not effective or efficient at part-load conditions. In many parts of the world, ductless heat pumps (DHPs) are the norm because of their simplicity, performance, and versatility.

Recent improvements in DHP technology have implications for their broader application in North America. In particular, field results from existing electrically-heated homes in the Pacific Northwest indicate a COP (coefficient of performance) of 4.5 @ 45˚ F outside temperature, and an approximate SEER of 20. Given California's climate, housing stock, and utility rate structure, under what conditions might DHPs be an appropriate space conditioning system for homes undergoing phased or "all at once" deep energy retrofits?

While several types of minisplits are available on the market this 2-part Thousand Home Challenge webinar focuses on single-head, inverter-driven ductless heat pumps. Topics include installation issues critical to performance, field monitoring and energy use data from the Northwest, and experience using DHPs as the primary space conditioning system in high performance New England buildings.

Part 1 of the webinar will feature presentations. In Part 2, Mark Jerome, Bob Davis, and Marc Rosenbaum will respond to questions and discuss issues raised by Tuesday's participants. Please join us for both.


By participating in this webinar, attendees will:

  1. Understand how the technology and installation of inverter-driven ductless heat pumps (DHP) differ from conventional residential air source heat pumps
  2. Find out what has been learned to date through the submetering of electrically-heated homes in the Pacific Northwest that have been upgraded to include a ductless heat pump
  3. Examine the opportunities and limitations for installing DHPs as part of either a "staged" or "all at once" deep energy reduction in Northern California, and low energy homes elsewhere


Bob Davis, Presenter

Bob Davis is a researcher and consultant at Ecotope in Portland, Oregon. For the past 20 years he has measured field performance of homes and small businesses. Bob is the field manager of two, year-long projects which are evaluating the performance of ductless minisplits in existing Pacific North West homes. These projects include 150 sites with DHPs installed from the Pacific Ocean to the Rockies. Bob's work includes design of instrumentation systems, construction of field protocols, oversight of installation crews, and field data management.

Mark Jerome, Presenter

Mark Jerome is the owner of KAM Energy, Roseburg, Oregon, a consulting, education, and testing company focusing on HVAC performance. He has built on his experience installing hundreds of ductless heat pumps, and is now involved in training and quality assurance. Mark understands the intersection between practical field reality and the challenge of implementing programs to improve residential HVAC performance. He has been a HVAC service technician for 27 years and continues to work part time for Pacific Air Comfort.

Marc Rosenbaum, P.E., Respondent

Marc Rosenbaum, P.E. is a long-time student of making great buildings. He uses an integrated systems design approach to help people create buildings and communities which connect us to the natural world, and support both personal and planetary health. Marc is a Passive House Consultant and trainer. Much of his recent work has been deep energy retrofits and zero net energy buildings in New England using minisplit heat pumps. He is the director of engineering for South Mountain Co., Inc. on Martha's Vineyard.