This standard specifies design criteria for water based heating systems in buildings with a maximum operating temperature of up to 105°C. In case of heating systems with maximum operating temperatures over 105°C other safety aspects than those described in 4.6 may apply. The other clauses of this standard are still valid for those systems. This standard does not cover additional safety requirements which may be applicable to heating systems greater than 1 MW design heat load. This standard does not amend product standards or product installation requirements. This standard covers the design of: - heat supply systems; - heat distribution systems; - heat emission systems; - control systems. This standard takes into account heating requirements of attached systems (e.g. domestic hot water, process heat, air conditioning, ventilation) in the design of a heat supply, but does not cover the design of these systems. This standard does not cover requirements for installation or commissioning or instructions for operation, maintenance and use of water based heating systems. This standard does not cover the design of fuel and energy supply systems.