Variable capacity equipment is usually more efficient than equipment that can only operate at constant speed or capacity. Ductless mini-split systems, utilize variable-speed inverter-driven compressors and fans. can save significant energy for most applications where the load changes with the seasons and time of day.
Heat pumps with variable speed compressors have been available in other countries for many years, commanding more than 80% of the commercial and residential market combined in Japan, Europe and China. This technology is now widely available in the U.S from multiple manufacturersCurrent Stage:
Approved for Implementation. See BPA Energy Efficiency Implementation Manual
and BPA Residential Programs page
for measure and program details.