Effective January 1, 2023, the federal government issued new standards for heat pump products which caused manufacturers to replace HSPF and SEER efficiency ratings with HSPF2 and SEER2. At that time, the Sponsors of Mass Save will update efficiency requirements for residentially-sized air source heat pump equipment (rated below 65,000 Btu/h of cooling capacity) to align with the new federal standards (i.e., ENERGY STAR 6.1 Cold Climate Certification standard). To ease the transition to the new standards, the Sponsors consider any models that meet either the previous criteria or the new criteria as eligible for installation through December 31, 2023. For more information click here. Please note that beginning January 1, 2024, only equipment that meets the ENERGY STAR 6.1 Cold Climate Certification standard will be eligible.