Ductless Mini-Split Heat Pump Comfort Evaluation
Ductless mini-split heat pumps (DMSHPs) offer an alternative to traditional central heating and cooling systems (CACs). Advantages of DMSHPs include:
- Reduce energy consumption
- Eliminate potential in-duct mold growth
- Eliminate duct losses
- Zone space conditioning
The Fraunhofer team performed field tests in two Austin, Texas homes to evaluate DMSHP comfort performance. Temperature and relative humidity (RH) data were evaluated for four spaces against ASHRAE 55 for clothing insulation (clo.) levels of 0.5 and 1.0:
- Living rooms: Time percentage within comfort zones was the same for DMSHPs and CACs indicating that the DMSHP operated much like a CAC system.
- Bedrooms: Residents preferred lower temperatures during the cooling season because more measured data fell within the 1.0 clo. comfort zone.
- Bathrooms: Most data fell outside of the 0.5 clo. and 1.0 clo. comfort zones due to high RH levels from a lack of indoor units.
In general, measurements indicated high RH levels that suggest residents chose to achieve lower RH by cooling the spaces or were unaware of the dehumidification mode. Overall, the temperature difference observed between all rooms within each house at an outdoor temperature of 85°F was approximately 3°F.