The highest efficiency home HVAC heat pump units currently available have a Coefficient of Performance (COP) of around 6.0 (eg Daikin US7). This is a small split system unit of around 2.5kW cooling/3.6kW heating, so enough for a medium sized room. The COP drops off considerably in the larger unit sizes. Most conventional inverter split system AC units would have a COP around 3.5-4.5. Larger commercial systems can be much more efficient with large Chiller COP’s around 10 but other parasitic system losses with pumps, pipes, ducts and fans generally bring the total system COP back well under 5.

The main contributors to home HVAC energy efficiency are the quality and design of the compressor, internal and external fan efficiencies, coil and filter pressure drops and controls. Going away from air cooled to water cooled or geothermal will also improve efficiency but also adds significant complexity and cost. Elon is talking about adding a HEPA filter and that will typically add extra pressure drop and energy unless the filter is very large. Quality component design and smart integration of the compressor motors, fans and controls should shave off energy. However there are limitations in physics/thermodynamics that will limit what is acheivable in a compact package. I expect they will still come up with a highly compelling home HVAC product but it may be as much for the AI/Controls and energy system integration as it is for energy efficiency and indoor air quality.