[hedgedoops2]

Heat pumps can't be more efficient than the theoretical Carnot heat engine running in reverse, whose efficiency is T_outside / delta_T. In this case it's (273-28)K/98K = 2.5.

I guess being 2x as efficient (cheap) as electric resistive heating isn't super-terrible, but it's not great either.

Compare this to a favorable groundwater heat pump configuration with good radiators and insulation where the 'outside' (groundwater) is maybe 10°C and the target temp 30°C (close to room temp): (273+10)K/20K = ~14.