Heat pump SEER2 ratings focus on energy efficiency during the cooling mode, akin to central air conditioners. SEER2 is a standard measure for comparing various heat pump and air conditioner units, with higher numbers indicating greater efficiency. SEER2 is computed by dividing the total heat removed from a home during the cooling season by the total operating hours during the same period, adjusting for varying temperature conditions. As of January 1, 2023, the Department of Energy mandates a minimum SEER2 efficiency of 14.3 for residential air-source split-system heat pumps. Heat pumps with ratings of 17 SEER2 and above are generally considered highly efficient, with some reaching up to 22 SEER2.