In Florida, space heating and space cooling is customarily accomplished by central systems with unavoidable air distribution losses as ducts – often leaky – pass through unconditioned space. High-efficiency 1-ton, supplemental, inverter-driven ductless mini-split heat pumps with a 25.5 seasonal energy efficiency ratio (SEER), and 12 heating seasonal performance factor (HSPF), were installed in the main living area of 10 central Florida homes with the goal of reducing space heating and cooling energy by decreasing runtime of these less efficient systems. The SEER rating is 1.8 times as efficient as the new federal minimum level for conventional central systems and even more efficient than the older systems in these homes
Installed as a supplement, the mini-split installations showed median energy savings of 33% (6.7 kWh/day) for space cooling and 59% (6.5 kWh/day) for heating in the existing homes where they were added. An added consumer benefit is a redundant heating and cooling system, creating tolerable interior conditions during main system failures.
Two additional homes received high-efficiency, ductless heat pumps as complete central system replacements – a single ducted unit and a multi-split design. These homes exhibited cooling energy use savings of 37% (7.8 kWh/day) and 29% (3.5 kWh/day), respectively. While significant cooling savings were measured, the multi-split installation suffered comfort issues. The mini-split replacement, however, showed superior interior moisture control and maintained the space 1oF lower on average.
*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.