Understanding the Net Zero Carbon Buildings Standard

Understanding the Net Zero Carbon Buildings Standard

The UK’s built environment is directly responsible for 25% of the UK’s emissions. It is therefore essential for the built environment sector to rapidly reduce emissions both from operational energy use, and from the emissions in building products (embodied carbon), to create sustainable ‘net zero carbon buildings’ that utilise low carbon materials, are long-lasting, highly energy efficient and use decarbonised forms of power. However, to date there have not been agreed definitions or methodologies as to what a ‘net zero carbon building’ should be and how it should be measured.

The Net Zero Carbon Buildings Standard (‘the Standard’) has sought to change that. Originally released as a pilot version in September 2024, with v2 of the pilot published in April 2025, the Standard provides a unified approach where UK buildings can show they are aligned to the UK’s net zero targets and Paris Agreement commitments, and gain the title ‘Net Zero Carbon Aligned’.

The Standard is an essential tool for all stakeholders across the built environment sector to measure, assess and communicate their sustainability and ESG goals at an asset level, including investors, property owners and managers, developers and construction companies.

Key components of the Standard

For a building to gain the ‘Net Zero Carbon Aligned’ accreditation, a detailed series of performance targets or limits must be met. These relate to 10 core metrics shown to the right.

The Standard adopts a ‘whole life carbon’ approach to buildings as performance targets and limits relate both to the construction and operation of an asset. A building cannot be accredited as ‘net zero in construction’ or ‘net zero in operation’ only.

At the heart of the Standard is an emphasis on measured performance data, rather than modelled or estimated data. In other words, during both the construction and operation of a building, data around energy use and material types and quantities must be collected and monitored. A building can only be verified as ‘Net Zero Carbon Aligned’ once at least one year of operational performance data has been collected.

The Standard applies to both new and existing buildings across a wide range of sectors (including residential, culture, data centres, leisure, healthcare, retail, hotels, offices, education and storage and distribution). Each sector has bespoke performance targets and limits. In order to encourage low-intensity retrofits, rather than large-scale demolition and rebuilding, the Standard sets out more stringent embodied carbon limits, but more relaxed operational energy limits for existing buildings compared to new builds.

Offsetting is optional and cannot be used to compensate for a lack of performance elsewhere – all other performance standards must be met, whether offsets are used or not. Offsets must be purchased from internationally recognised standards and retired within five years of the ‘vintage’ year of the credits.

Challenges for the sector

Whilst the adoption of a unified methodology to define a net zero carbon building is welcome, it comes with challenges for the built environment sector. These include:

• An additional regular reporting burden. For a building to remain accredited, detailed performance data must be collected and calculated yearly, on top of the existing reporting burden, in a standard reporting format. The data needs to then be verified externally (no comment yet on approved verification bodies).
• More embodied carbon reporting requirements than many stakeholders will be used to meeting. Embodied carbon limits have been set in relation to upfront carbon (i.e. Life Cycle Assessment modules A1-A5, product manufacture, transport to the site and construction), and in future versions whole-life carbon (i.e. modules A-C, building whole lifetime including end of life) are proposed. These limits apply to both new builds and refurbishments.
• Buildings must install a minimum amount of renewable energy, (i.e. roof-mounted solar panels for the vast majority of buildings). Exemptions apply, for example where existing buildings do not have the structural capacity, or there are planning or heritage constraints.
• Buildings must be ‘fossil fuel free’. Aside from emergency backup systems, and fuel use during construction, no fossil fuels may be used in buildings (whether new or existing). As such, no buildings with active gas boilers can be ‘Net Zero Carbon Aligned’.

Aligning with existing standards

The Standard joins a growing list of net zero-focused initiatives for the built environment sector, such as the Science Based Targets Initiative’s (SBTi) building sector pathway and the Carbon Risk Real Estate Monitor (CRREM), alongside regional sustainability requirements such as London’s whole life carbon assessment requirements.

• SBTi Building Sector Pathway. Both the Net Zero Standard and the SBTi take a whole building approach to emission monitoring and reduction, grouping together operational emissions from landlord and tenant spaces, and setting intensity targets based on floor area. The SBTi pathway also includes targets for embodied emissions for new developments. However, it is important to note that the SBTi pathway is a portfolio-level tool, and as such does not have asset-specific performance targets. The SBTi pathway also does not include emissions from refurbishment works.
• Carbon Risk Real Estate Monitor (CRREM). CRREM, like the Net Zero Standard, provides operational energy use intensity pathways at an asset-specific level, which have been designed to be in line with a 1.5C warming trajectory. The CRREM pathways are most similar to the Standard’s ‘stepped retrofit’ intensity pathways, as these are both aimed at existing buildings, with future refurbishment work over time. The Net Zero Standard pathways are in general slightly more stringent than the CRREM pathways, and as such a building meeting the Net Zero Standard is likely to be CRREM-aligned (though not in all cases – for example, the CRREM energy limits for hotels are more stringent than the Net Zero Standard limits). Note that CRREM is relevant for operational energy intensity only, and does not cover other Net Zero Standard elements (such as embodied carbon).
• Greater London Authority (GLA) Whole Life Carbon assessments. For large new developments in London, whole life carbon assessments must be undertaken at the planning stage. The methodology for undertaking these whole life carbon assessments is aligned to the Net Zero Standard, and there are also embodied emission benchmarks that new developments should not exceed (though note that the Net Zero Standard has considerably stricter embodied emission targets). However, the GLA’s requirements relate to forward-looking emissions at planning stage, whilst the Net Zero Standard requires measured performance data. As such, whole life carbon assessments submitted to the GLA would not be enough to satisfy the Net Zero Standard’s requirements, though would provide a useful indication of whether the building would meet the Net Zero Standard requirements once constructed and operational.

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