In cold countries a typical new installation will have an air-to-water or ground-to-water heat-pump for heating with an integrated hot water tank (actually more

In cold countries a typical new installation will have an air-to-water or ground-to-water heat-pump for heating with an integrated hot water tank (actually more like a warm water tank for efficiency reasons). Hot water is a considerable fraction of energy cost in a well insulated home and reducing it many-fold by the typical COP of a heat pump makes a lot of sense.