 Heat pumps are already at a price disadvantage when it comes to initial investment (not long-term savings) compared to conventional heating solutions like boilers, so the drive towards more efficient heat pumps and air conditioners is often led by legislative measures on minimum efficiency standards.Electricity rates will also influence the attractiveness of heat pumps.In cooling mode, a heat pump's operating performance is described in the US as its energy efficiency ratio (EER) or seasonal energy efficiency ratio (SEER), and both measures have units of BTU/(h·W) (1 BTU/(h·W) = 0.293 W/W).