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Building regulations circular
Circular number: WGC 001/2023
Date issued: 28/03/2023
Status: For information
Title: Notice of approval of updated calculation methodologies in Wales
Issued by: Colin Blick, Building Standards Technical Manager
Local Authority Chief Executives
Welsh Local Government Association
Association of Corporate Approved Inspectors
Construction Industry Council
Competent Persons Forum
Please forward to:
Local Authority Building Control Officers
Members of the Senedd
In accordance with the requirements of the Building Regulations 2010 this circular informs of the updated calculation methodologies for the energy performance of buildings in Wales.
For further information contact:
Building Regulations Team
Welsh Government Offices
Notice of approval for calculation methodologies
- I am directed by Welsh Ministers to inform you of the issue of a new notice of approval for the updated calculation methodologies.
Scope of this Circular Letter
- This Circular letter applies to buildings and building work in Wales.
Notice of approval for the methodologies of calculation of the energy performance of buildings
- Regulations 25, 26, 26A, 26B, 26C, 27, 27A, 27B and 27C of the Building Regulations 2010 require that the calculation of energy performance of new buildings shall be carried out using a methodology approved by the Welsh Ministers under regulation 24 of those Regulations.
- To coincide with the coming into effect of amendments to the energy efficiency requirements of the Building Regulations for ‘buildings other than dwellings’, a notice of approval for updated approved methodologies is attached at Annex A.
- The coming into effect date for the approved methodologies is 29 March 2023. The notice sets out what buildings to which the updated methodologies will apply and where previous versions of the methodologies may continue to be used.
Any enquiries on this Circular Letter should be addressed to:
Head of Planning
Notice of Approval of the methodologies of calculation of the energy performance of buildings to demonstrate compliance with the Building Regulations 2010 in Wales.
This notice of approval sets out the national approved calculation methodologies (NCM) for calculating the energy performance of certain buildings in Wales in accordance with regulation 24 and for the purposes of regulation 25 of the Building Regulations 2010 (SI 2010/2214).
This document does not apply to national calculation methodologies in England, Northern Ireland and Scotland, which are subject to separate regulatory requirements.
The notice of approval for calculating the energy performance of buildings as required by the Energy Performance of Buildings (England and Wales) Regulations 2012 is issued as a separate document by the Department for Levelling Up, Housing and Communities. Methodologies for expressing the energy performance of buildings in England and Wales: notice of approval (GOV.UK)
Notice of Approval
TAKE NOTICE that the Welsh Ministers, under regulation 24 of the Building Regulations 2010, hereby approve the methodologies listed below for the calculation of the energy performance of buildings for the purposes of regulation 25 (Minimum energy performance requirements for new buildings) of the Building Regulations 2010.
This approval takes effect on 29 March 2023 and supersedes the previous approvals which took effect from the 23 November 2022, 30 April 2015, 31 July 2014, and 2 October 2014. This approval continues in effect until withdrawn by Welsh Ministers or superseded.
This approval does not apply in respect of:
(a) building work started on a particular building before 23 November 2022 for ‘dwellings’ and 29 March 2023 for ‘buildings other than dwellings’ in accordance with any relevant notification provision; or
(b) where a relevant notification provision on an individual building has been given before 23 November 2022 for ‘dwellings’ and 29 March 2023 for ‘buildings other than dwellings’ provided the work for each building is started before 23 November 2023 for ‘dwellings’ and 29 March 2024 for ‘buildings other than dwellings’.
(c) sites where a relevant notification provision was complied with before 31 July 2014 and building work commenced before 31 July 2015.
“Relevant notification provision” means notification of building work under regulation 12(2) of the Building Regulations 2010, or sections 47(1), 50, 51A(2) or 54 of the Building Act 1984.
In these cases earlier versions of the methodologies may continue to be used.
The approved methodologies are:
from the 23 November 2022;
a. the UK Government’s Standard Assessment Procedure (SAP) for the Energy Rating of Dwellings, 10.2 edition; and
From the 29 March 2023;
b. the National Calculation Methodology (NCM) for buildings other than dwellings in Wales, 2022 version.
Minister for Climate Change
Notes on the approved methodologies
This notice of approval sets out the ways of expressing the energy performance of buildings, as calculated in accordance with the methodology approved by Welsh Ministers under regulation 24, for the purposes of regulation 25, 25C and 25D (Minimum energy performance requirements for new buildings) of the Buildings Regulations 2010.
Software packages and interfaces
To use the approved methodologies it is also necessary to use only the approved software packages and interfaces relating to them. The currently approved software packages and interfaces are available at:
New domestic buildings:
New Non-domestic buildings:
Please note that from time to time the list at this link is revised to include new software applications or new versions of existing ones as they are approved.
Calculating the energy performance of new dwellings
For the purposes of compliance with regulations 25, 25C, 25D, 26, 26A, 26B, 26C, 27, 27A, 27B and 27C of the Buildings Regulations 2010, SAP 10.2 shall be used to calculate for the dwelling as designed and constructed:
- the target CO2 emission rate
- target primary energy rate
- target fabric performance values
- minimum energy efficiency rate
- calculated CO2 emission rate
- calculated primary energy rate
- calculated fabric performance values, and
- the calculated energy efficiency rate.
Calculating the energy performance of new buildings other than dwellings
For the purposes of regulations 25, 26, 26A, 27 and 27A of the Building Regulations, the target CO2 emission rate, target primary energy rate, the calculated CO2 emission rate and the calculated primary energy rate for a building other than a dwelling as designed and constructed, shall be calculated using an approved implementation of the National Calculation Methodology for buildings other than dwellings, i.e. SBEM version 6.1 or an approved DSM.
Approval of commercial software calculation tools
Applications may be made to Welsh Ministers for approval of software packages to form part of the methodology for the calculation of the energy performance of buildings, such as:
a. software applications of SAP;
b. software interfaces with SBEM;
c. Dynamic Simulation Models (DSMs).
To be approved, the software tool must be validated against a set of published criteria to ensure it operates in a manner and to a standard consistent with the NCM before it can be approved by Welsh Ministers. The criteria for approval and the procedures for applying for approval may be obtained from: