Building America Team: University of Central Florida

Partners: Mitsubishi and AirCycler

Photo of the interior of a home with a mini-split heat pump.

This project is refining a new approach to using mini-split heat pumps in existing homes. The team will focus on using a single, centrally located mini-split heat pump as the primary system, while only using the existing, lower-efficiency central system as needed. They will also develop an integrated controller to better coordinate operation of the mini-split and the central system. The team will then create best-practice guidance for optimum design, installation, system control, and central system replacement at end-of-life.

A new approach generates significant heating and cooling savings for existing homes by using a centrally-located mini-split heat pump as the primary conditioning system in coordination with lower-efficiency central systems.

Previous University of Central Florida research documented 34% average heating and cooling energy savings for Florida homes that utilize this novel approach. The integrated controller developed as part of this project is expected to enable additional savings and improve comfort. Best practice guidance for optimum design, installation, system control, and central system replacement at end-of-life will be developed to foster mainstream adoption of the approach.


  • Demonstrated persistence of cooling energy savings with supplemental mini-split heat pump (MSHP)
  • Demonstrated ability to maintain comfort within Air Conditioning Contractors of America (ACCA) Manual Residential Systems (RS) guidelines (bedrooms < 3oF delta from living room)
  • Demonstrated ability to enhance cooling energy savings and maintain comfort with set point optimization and periodic (nighttime) fan cycling
  • Selection of hardware for Integrated Controller Design
    • Nest for central systems
    • Sensibo for mini-splits
  • Developed Integrated Controller Design software algorithm.
Photo of the mini-existing heat pump outside.

Remaining work:

  • Complete controller experiments
    • Finalize controller algorithm
    • Collect and analyze data for energy savings and comfort
  • Conduct central system end-of-life simulations
    • Develop multizone EnergyPlus model.


For more information, project presentations, and related publications, visit the Integrated HVAC Control Methods for Supplemental High Efficiency Mini-Split Heat Pumps in Existing Homes webpage