# The Environmental Authorisations (Scotland) Regulations 2018, Paragraph 10: Determining the efficiency of the cogeneration process


(1) Values used for calculation of efficiency of cogeneration and primary energy savings are to be determined on the basis of the expected or actual operation of the unit under normal conditions of use.
(2) For the purposes of this schedule, high-efficiency cogeneration must fulfil the following criteria—
(a) cogeneration production from cogeneration units must provide primary energy savings calculated according to sub-paragraph (3) of at least 10% compared with the references for separate production of heat and electricity,
(b) production from small-scale and micro-cogeneration units providing primary energy savings may qualify as high-efficiency cogeneration where SEPA determines that they qualify as high-efficiency cogeneration.
(3) Calculation of primary energy savings provided by cogeneration production other than by micro-cogeneration units, is to be calculated on the basis of the following formula—
PES=1-1CHP HŋRef Hŋ±CHP EŋRef Eŋ×100%
(4) In sub-paragraph (3)—
(a) “PES” is primary energy savings,
(b) “CHP Hŋ” is the heat efficiency of the cogeneration production defined as annual useful heat output divided by the fuel input used to produce the sum of useful heat output and electricity from cogeneration,
(c) “Ref Hη” is the efficiency reference value for separate heat production,
(d) “CHP Eη” is the electrical efficiency of the cogeneration production defined as annual electricity from cogeneration divided by the fuel input used to produce the sum of useful heat output and electricity from cogeneration; where a cogeneration unit generates mechanical energy, the annual electricity from cogeneration may be increased by an additional element representing the amount of electricity, which is equivalent to that of mechanical energy,
(e) “Ref Eη” is the efficiency reference value for separate electricity production.
(5) SEPA may use reporting periods other than annually for the purpose of the calculation in sub-paragraph (3).
(6) the calculation of primary energy savings for micro-cogeneration units may be based on certified data.

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Source: https://www.legislation.gov.uk/ssi/2018/219/schedule/25/paragraph/10 (the official version)
Page: https://openlegislation.uk/environmental-authorisations-scotland-regulations-2018/schedule-25/paragraph-10
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.