# Commission Regulation (EU) No 813/2013 of 2 August 2013 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for space heaters and combination heaters (Text with EEA relevance), Division (12)

Extent: E+W+S+N.I.

‘useful efficiency’ (η) means the ratio of the useful heat output and the total energy input of a boiler space heater, boiler combination heater or cogeneration space heater, expressed in %, whereby the total energy input is expressed in terms of GCV and/or in terms of final energy multiplied by CC;

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Source: https://www.legislation.gov.uk/eur/2013/813/annex/I/division/2/division/12 (the official version)
Page: https://openlegislation.uk/eu-regulation-2013-813/annex-I/division-2/division-12
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.