This standard describes a laboratory method for measuring the energy use of a thermostatic mixer, consisting of a shower head, hose, and connections to water supply pipes, setting out the requirement criteria for energy efficiency. The energy efficiency of the mixer provides a basis for energy classification. The overall objective of the standard is to encourage the development of technical designs that contribute to energy efficiency of sanitary tapware, with particular emphasis on designs that aim to improve energy efficiency rather than simply to limit water flow, i.e. which encourage the user to use less hot water for a given purpose.