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The definitions on this website (and published in our Climate Contract Playbook) have been prepared in good faith on a pro bono basis and are free to download and use. The definitions have been drafted and edited by a variety of lawyers and, as such, the approaches to drafting may not conform to any particular drafting norms. We acknowledge this as a consequence of the collaborative drafting process.
The definitions on this website (and published in our Climate Contract Playbook) are provided on an ‘as is’ basis and without any representation or warranty as to accuracy or that the definitions will achieve the relevant climate goal or any other outcome.
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Zero Carbon Housing
Zero Carbon Housing: has the same meaning as Level 6 of the Code for Sustainable Homes [or any successor or equivalent standard].
Zero Carbon Homes
Option 1 (design and construction of new homes definition - 'dark green')
Zero Carbon Homes means dwellings that are designed to [maximum energy efficiency standards/ Passive House standards/ BREEAM rating outstanding] and to be heated and powered only through [on-site/off-site] renewable technologies and where their construction has resulted in net zero carbon emissions including through efficient methods of construction, the use of materials with low Embodied Carbon and the use of Carbon Offsetting for [unavoidable/ residual] emissions.
Option 2 (operational energy definition)
Zero Carbon Homes means highly energy efficient dwellings where the operational energy requirements are met by on-site or off-site renewable energy technologies so that the use of the building results in zero Greenhouse Gas Emissions.
Option 3 (retrofitting definition)
Zero Carbon Homes means dwellings that have been modified to improve their energy efficiency so that following completion of the [retrofitting] works their operational energy use results in zero Greenhouse Gas Emissions and where the [retrofitting] works use materials with low Embodied Carbon.
Option 4 (definitions based on the UK Green Building Council’s (UKGBC) Net Zero Carbon Buildings: A Framework Definition (April 2019))
Net Zero Carbon Building means, in relation to the construction of that building where the amount of carbon emissions associated with a building’s product and construction stages up to practical completion is zero or negative, through the use of offsets or the net export of on-site renewable energy.
Net Zero Carbon Building means a highly energy efficient building powered from on-site [and/or] off-site renewable energy sources, with any remaining carbon balance offset so that the amount of carbon emissions associated with the
building’s operational energy on an annual basis is zero or negative.
Low or Zero Carbon (LZC)
Low or Zero Carbon (LZC) which is used in a RICS publication (RICS: The future of policy and standards for low and zero carbon homes (PDF) (see References below).
Nearly Zero Energy Buildings Target (NZEB)
Nearly Zero Energy Buildings Target (NZEB) as defined by the European Commission (European Commission: Nearly zero-energy buildings (see References below).
Ultra Low Energy Buildings (ULEBs)
Ultra Low Energy Buildings (ULEBs) means buildings that achieve the lowest GHG emissions through energy efficiency measures alone. This definition is based on bigEE’s policy roadmap for ULEBs (see References below).
Options 2 (Design and construction of new homes definition (dark green)) and 3 (Operational energy definition) follow the approach taken in the UK Green Building Council’s Net Zero Carbon Buildings: A Framework Definition (see References below) by splitting out the operational energy and construction/ design aspects of a zero carbon building.
Option 2 is an ambitious definition that requires the design of a zero carbon home to ensure that it will operate with maximum energy efficiency as well as ensure that the construction process results in zero carbon emissions. It includes an option to reference either a BREAM rating or Passive House standards as a way of assessing the design of the housing.
Related terms – ULEBs
bigEE distinguishes ULEBs and NZEBs based on the latter’s inclusion of buildingintegrated renewable energy technologies in addition to the ULEB design.
Development agreements, construction contracts, leases, real estate financing documents.
Ministry of Housing, Communities & Local Government: Code for Sustainable Homes (20 May 2014) (Note that this publication was withdrawn following a technical housing standards review, and is now used for administering legacy cases only.)