There are a wide range of assessment tools and methodologies available for use within the UK construction industry.  NBS Technical Author Michele Lucarelli introduces the most common.

The Government wants to see 'zero carbon' performance for all new homes by 2016 (2011 in Wales) and for all new non-domestic buildings by 2019.

The drive to reduce carbon dioxide emissions has resulted in a plethora of standards and assessment systems for determining the environmental impact of both domestic and non-domestic buildings or construction projects. Some are carbon focused, some have a wider sustainability remit. Here we offer a simple overview of some of the main statutory and voluntary systems, and associated terminologies, that may currently be encountered in the UK.

Background legislation

EPBD (Energy Performance of Buildings Directive) – Requires the labelling of buildings in terms of energy performance and carbon dioxide emissions. In England and Wales this has manifested itself in the Energy Performance of Buildings Regulations which require production of Energy Performance Certificates (EPC) for all properties – homes, commercial and public buildings – when bought, sold, built or rented. Larger public buildings must also have a Display Energy Certificate (DEC). Certificates must be produced by an accredited assessor, using the relevant calculation tool in the National Calculation Methodology (NCM).

(Note: Further measures to reduce greenhouse gases may be prompted by the 'carbon budgets' due to be set as a requirement of the Climate Change Act 2008; carbon budgets are due Spring 2009 alongside the fiscal Budget.)

Building Regulations – Require the assessment of potential emissions and effectively establishes minimum energy performance. Methodologies cited: SAP (Standard Assessment Procedure), used for calculating carbon dioxide emissions rate for new build dwellings within Part L (E&W), Section 6 (Scot), Part F (NI); SBEM (Simplified Building Energy Model), used as default for calculating energy use in new buildings other than dwellings under the respective UK building regulations. (Elemental methods are generally used for work to existing buildings.)

Assessment systems and tools

CLG (Communities and Local Government) Code for Sustainable Homes (CfSH or CSH) (based on BREEAM's EcoHomes) – Mandatory for new housing in England from 1 May 2008. Considers nine areas of sustainability including energy use and, notably, water consumption, with six levels achievable, Level One being the lowest, Level Six ('carbon neutral') being the highest. Houses do not have to be built to the Code, but are 'nil-rated' if built only to current Building Regulations. The standards in the Code are, however, increasingly working their way into the Building Regulations, with the next edition of Part L, particularly, anticipated to reflect the content of the code.

BREEAM (previously Building Research Establishment Environmental Assessment Method) – Non-domestic design-stage methodology based on building type models. Voluntary, but higher ratings scores increasingly being required by funding bodies such as the Department for Children, Schools and Families (DCSF) and NHS. Considers nine areas of sustainability. Ratings attainable: Unclassified; Pass; Good; Very Good; Excellent; and Outstanding. 2008 models improved by encompassing post construction verification of agreed design.

Current (2008) models:

  • Education (previously 'Schools'; excludes tertiary education)
  • Courts
  • Bespoke (for projects which fall outside the defined models)
  • Gulf
  • Healthcare (previously NEAT – NHS Environmental Assessment Tool)
  • Prisons
  • Industrial
  • Multi-residential
  • Offices
  • Retail
  • Communities (due for release; tool for planners and developers to assess the sustainability of development proposals at the planning stage)
  • International (BREEAM-tailored model which can be developed for any development, corporation, region or country)
  • Further education (due for release)


BREEAM EcoHomes – Version of BREEAM, but for homes, forerunner of CfSH. Voluntary. Considers eight areas of sustainability. Ratings attainable: Pass; Good; Very Good; Excellent. Since the introduction of CfSH now applicable for refurbishment of homes only in England, and for new build as advocated by commissioning bodies in Wales, Scotland, N. Ireland, and potentially abroad.

BREEAM EcoHomes XB – Self-assessment stock profiling tool for existing housing stock holders. Voluntary. Allows environmental performance to be assessed and monitored through benchmarking and target-setting.

BREEAM HealthcareXB – Credits-based self-assessment tool for existing healthcare buildings in operation. Voluntary. Certification requires BREEAM Healthcare assessor input.

Other BREEAM tools, but not assessment systems in themselves:

BREEAM Envest2: web-based tool for considering building fabric and model proposal in relation to whole life costs, allowing optimum environmental impact solutions to be determined at early design stage.

BREEAM LCA (Life cycle assessment) Environmental profiles: method of identifying and assessing the environmental effects associated with building materials based on life cycle analysis. Can be used in conjunction with BREEAM model methodologies and CfSH.

BREEAM Specification, 'The Green Guide': (hard copy and online), gives environmental ratings based on Ecopoints for comparable generic building components and specifications. Also for use when applying BREEAM model methodologies.

Further assessment systems, tools and programmes

AECB (Sustainable Building Association – previously the Association for Environment Conscious Building) CarbonLite. Developed with support from the Carbon Trust. Voluntary. Focuses on minimising energy use and reducing carbon emissions, and can be applied to both domestic and small scale non-domestic new build. Currently uses the German PHPP (PassivHaus Planning Package) to calculate energy use and emissions from energy standards established through research based on real occupancy examples. It is hoped to transfer to BREDEM (BRE Domestic Energy Model) when and if this is modified to more accurately reflect current usage patterns in AECB's view. Unlike CfSH, the methodology considers primary energy – i.e. emissions through generation, not just energy consumed at point of use – and also acknowledges the carbon emission 'weight' of different fuels. Ongoing post-occupancy energy use is measured through smart metering. Embodied energy of the building fabric is not considered, although this is justified by AECB by noting this is a relatively small carbon cost compared to the benefits over the lifetime of the building.

Three awards achievable: Silver (equivalent to CfSH 4); PassivHaus (equivalent to CfSH 5); Gold (equivalent to CfSH 6). Gold is carbon neutral and takes into account appliances in use.

PassivHaus UK – Administered through the BRE. Voluntary. (NB European Directives may soon promote PassivHaus or equivalent for both new domestic and non-domestic construction. In the UK CfSH 5 currently meets the standard for homes, but there is no requirement for other building types.) Sets a series of high standards for performance, including energy saving household appliances, and, again unlike CfSH, takes into account primary energy use.

USGBC (U.S. Green Building Council) LEED (Leadership in Energy and Environmental Design) – Comparable to BREEAM. Used on projects in over 40 different countries including US, Brazil, Canada, India, and Mexico. Voluntary, but as with BREEAM, increasingly publicly funded projects must meet the higher standards. Considers six areas of sustainability. Ratings attainable: Certified; Silver; Gold; Platinum. (N.B. Input is required in imperial units.)

Current models:

  • New construction
  • Existing buildings: Operation and maintenance
  • Commercial interiors
  • Core and shell
  • Schools
  • Retail
  • Healthcare
  • Homes
  • Neighborhood development

EST (Energy Savings Trust) 'Best practice' – Relates to residential buildings. Previously 'Best practice standards' ('Good' 'Best' and 'Advanced', but now encompassed in the standards required to meet CfSH). EST do however continue to provide best practice guidance to achieve the energy element requirements for the various CfSH ratings and for improvement of existing stock, with focus on 'Hard to Treat' (HTT) properties.

NCM (National Calculation Methodology) – Developed for CLG to implement the EPBD and allow conformity with Building Regulations to be assessed. Specifies use of particular methodologies for energy performance dependant on building type or data available.

BREDEM (BRE Domestic Energy Model) – Building-in-use model informed by data collected by monitoring real occupancy patterns (considered by some outmoded due to current life style patterns). Used to derive energy and emissions projections and forms a platform for SAP.

SAP (Standard Assessment Procedure) – Energy rating calculator specified in the NCM for dwellings. Mandatory or subject to use of approved alternatives. Used for domestic energy performance certification (EPC)and can be used to demonstrate respective building regulations (England, Wales, Scotland and Northern Ireland) compliance. Assumptions used in the programme are based on BREDEM. Various bodies (e.g. NHER – National Home Energy Rating) produce software that allows SAP calculations to be carried out and EPCs to be produced.

RdSAP (Reduced Data Standard Assessment Procedure) – For use in producing EPCs for existing dwellings where sufficient data cannot be obtained to carry out a full SAP rating.

SBEM (Simplified Building Energy Model) – Calculator developed for CLG by BRE (user interface: iSBEM). Mandatory subject to use of approved alternatives. Used for buildings other than dwellings to produce energy performance certification (EPC) and can be used to demonstrate respective building regulations (England, Wales, Scotland and Northern Ireland) compliance.

DSM (Dynamic Simulation Model) – Substitute for SBEM where SBEM is not sophisticated enough to accurately assess a building's energy efficiency. Use of the model requires CLG approval.

ORM (Operational Rating Methodology) – Required for DECs for larger public buildings. Defined by the CLG.

See also:

CIBSE (Chartered Institution of Building Services Engineers) publications – Best practice guidance and benchmarks are available covering, e.g. EPBD compliance and energy efficiency in buildings. See CIBSE TM22 Energy assessment and reporting method and CIBSE Guide F Energy efficiency in buildings.

DfES (Department for Education and Skills, now DCSF) Building Bulletin 87 Guidelines for Environmental Design in Schools May 2003 – Provides advice on optimising the energy and environmental performance of new and refurbished school buildings.

Note:  'True zero carbon building': "Where the net carbon dioxide emissions resulting from energy consumed in the operation of the space heating/ cooling, hot water systems, ventilation, internal lighting AND process related energy consumption is zero or better. The calculation of CO2 emissions can take account of contributions from on-site, near-site and accredited external renewable/ low carbon installations. " [BREEAM 2008].