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Commercial EPC glossary: the terms on your certificate explained

Updated 23 October 2026 · SEO Dons Editorial

How do the terms fit together?

The vocabulary makes most sense in the order a certificate is produced.

  1. An accredited assessor, who belongs to an accreditation scheme, surveys the building and splits it into zones.
  2. The data goes into approved software that applies the National Calculation Methodology (NCM). The software is either SBEM or a dynamic simulation model (DSM), and which one is used sets the assessment level.
  3. The software compares the building with a reference building and gives an asset rating, shown as a band from A+ to G, with a recommendation report.
  4. The assessor lodges the result on the register, which assigns the report reference number (RRN).

A Display Energy Certificate (DEC) differs: it reports an operational rating taken from metered use.

Rating and scale terms

Asset rating

The 2012 Regulations define it as "an energy performance indicator determined from the amount of energy estimated to meet the different needs associated with a standardised use of a building". It is the rating a commercial EPC headlines, and it comes from a model, not from your bills. How commercial EPC ratings are worked out covers the calculation.

Building emission rate (BER) and target emission rate (TER)

The government's 2023 consultation on future standards says the emission rate quantifies the CO2 equivalent emissions from a building's heating, cooling, hot water, pumps, fans, lighting and renewable generation. Its table of non-domestic metrics pairs a building emission rate with a target emission rate. The TER belongs to the new-build compliance check: regulation 26 of the Building Regulations 2010 says a building that is erected shall not exceed the target.

Reference building and notional building

The government's EPC guide says the rating process compares the building with a reference building, "an equivalent building (i.e. a building of the same size, shape and use as the actual building) constructed to a notional building designed to a specified standard". The NCM website describes the notional building in similar terms.

Environmental impact rating (EIR)

The EIR is the carbon-based headline metric on a non-domestic EPC. The government's technical annex says it is a normalised score of 1 to 150 for non-domestic buildings, and that the headline "Energy Rating" is, despite its name, a carbon emissions metric. The government's partial response says it will maintain the EIR as the non-domestic headline.

A+ (net zero)

Elmhurst Energy, an accreditation scheme, describes the commercial scale as A+ to G, "A+ indicating net zero and G being the worst performing". The government's statistics notes agree that for non-domestic properties A+ is the most efficient band.

Total useful floor area

The regulations define it as "the gross floor area as measured in accordance with the guidance issued from time to time by the Royal Institution of Chartered Surveyors". Thresholds such as 250, 500 and 1,000 square metres use this measure, and how floor area is measured on a commercial EPC explains the detail.

Calculation terms and levels

National Calculation Methodology (NCM)

The NCM website says it was "developed for HSE to assess the energy performance of buildings for the purposes of compliance with building regulations and energy certification". It is the method behind both SBEM and DSM, and the notice of approval that took effect on 24 March 2026 requires non-dwelling EPCs to use an approved implementation of it.

SBEM

SBEM stands for Simplified Building Energy Model. The NCM website describes it as a computer program that analyses a non-domestic building's energy consumption under standardised operating conditions.

Dynamic simulation modelling (DSM)

A DSM is, in the government guide's words, "a software tool that models energy inputs and outputs for different types of building over time". It is used where SBEM may not be sophisticated enough to give an accurate assessment. Can a Level 5 (DSM) EPC change your rating? looks at what it can model differently.

Levels 3, 4 and 5

The guide says levels 3 and 4 may both be assessed with SBEM and that currently the only distinction between them is the heating, ventilation and air conditioning. Level 5 buildings are those assessed with a dynamic simulation model. The level follows the building and shapes the fee, as the commercial EPC cost guide sets out. SBEM Level 3 vs Level 4 vs DSM gives the dividing lines, and Level 5 EPC cost covers DSM fees.

Assessors and schemes

Non-domestic energy assessor (NDEA)

The guide says EPCs for non-dwellings "must be produced by an accredited non-domestic energy assessor, who is a member of a government approved accreditation scheme". The regulations define an energy assessor as an individual who is a member of an accreditation scheme.

Accreditation scheme

An energy assessor must be a member of an accreditation scheme approved by the Secretary of State. The guide says the schemes manage their assessors and monitor the quality of the EPCs they produce. A scheme's approval can be limited to certain categories of building, so an assessor accredited for one category may not be able to certify another.

Register and certificate terms

Lodgement

Lodging means entering the assessment data onto the central register. The regulations require the assessor to do this before giving the document to the person who asked for it, and the guide says an EPC must be lodged once produced. An EPC and its recommendation report are only valid once lodged. How long a commercial EPC is valid explains the clock that starts at lodgement.

Report reference number (RRN)

The regulations define it as "the unique number assigned by the keeper of the register to each energy performance certificate". You can use it to search the register or check a certificate's authenticity. The guide also calls it the certificate reference number. How to find a commercial EPC on the register shows where to use it.

Recommendation report

The regulations define it as "recommendations made by an energy assessor for the cost-effective improvement of the energy performance of a building". The guide says recommendations come in four categories: short-term payback (under 3 years), medium-term (3 to 7 years), long-term (over 7 years) and other. How to read a commercial EPC recommendation report goes through it, and how to read a commercial EPC certificate covers the certificate.

NDEPC

NDEPC is shorthand for non-domestic energy performance certificate. In the official sources it appears in the name of the Non-Domestic Energy Performance Certificate (NDEPC) Conventions Group, which agrees the conventions that assessors in England and Wales follow. The NCM website says those conventions are circulated by the accreditation schemes to their assessors.

DECs and Scotland

Display energy certificate (DEC) and operational rating

The regulations define an operational rating as an indicator "determined from the amount of energy consumed during the occupation of a building over a period of time". A DEC shows that rating, based on actual consumption over the last 12 months, and typical performance for a building type scores 100. The duty falls on public authority occupiers, as Display Energy Certificates: which buildings need a DEC? explains.

Section 63

This refers to regulations made under section 63 of the Climate Change (Scotland) Act 2009, the Assessment of Energy Performance of Non-domestic Buildings (Scotland) Regulations 2016. They apply to buildings over 1,000 square metres and are triggered by a sale or a lease to a new tenant. For the Scottish rules, see commercial EPCs in Scotland.

Sources

Common questions

What does SBEM stand for in construction?

SBEM stands for Simplified Building Energy Model. It is a computer program that analyses a non-domestic building's energy consumption under standardised operating conditions, and government has adopted it as part of the UK national methodology.

What does NDEPC mean?

It is shorthand for non-domestic energy performance certificate. The official sources use it in the name of the NDEPC Conventions Group, whose conventions apply to assessments in England and Wales only.

Where do I find my EPC certificate number?

On the certificate itself: the guide says all EPCs must contain a valid certificate reference number. If it has been mislaid, the guide says you can search the register by the building's postcode instead.

Does every EPC include a recommendation report?

Regulation 9 says an EPC must include one unless there is no reasonable potential for energy performance improvements. The guide adds that there is no statutory requirement to carry out any of the recommended measures.

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