This European Standard specifies inspection procedures and optional measurement methods for the assessment of energy performance of existing boilers and heating systems. Boiler types covered by this European Standard are: boilers for heating, domestic hot water or both; gas, liquid or solid fuel fired boilers. Parts of heating systems covered by this European Standard are: boilers, including generation control; other generation devices; domestic hot water production facilities; heating distribution network, including associated components and controls; heat emitters, including components and controls; space heating control system; storage and associated components; domestic hot water control system. This standard covers issues related to energy conservation and environmental performance.