This standard specifies design criteria for heating systems in buildings using electrically driven heat pumps alone or in combination with other heat generators. Heat pump systems considered include (see Table 1):- water - water;- water - air;- brine - water;- refrigerant - water (direct expansion systems);- refrigerant - refrigerant;- air - air;- air - water.This standard takes into account the heating requirements of attached systems (e.g. domestic hot water) in the design of heat supply, but does not cover the design of these systems. This standard covers only the aspects dealing with the heat pump, the interface with the heat distribution system and hea