What is the UK Net Zero Carbon Buildings Standard?

The UK Net Zero Carbon Buildings Standard (UK NZCBS) defines how buildings can achieve net zero carbon alignment. It sets limits for embodied carbon, operational energy, district heating, fossil fuel use, refrigerants, and more, creating a science-led framework to decarbonise the built environment in alignment with the UK's climate goals.

What is the UK Net Zero Carbon Buildings Standard?

The UK Net Zero Carbon Buildings Standard (UK NZCBS) is a comprehensive framework aimed at defining and verifying what it means for buildings in the UK to truly be net zero carbon. Developed through a collaboration of leading industry organisations, including BBP, BRE, RIBA, RICS, LETI, and UKGBC, the standard provides clear, science-led guidance for reducing the carbon impact of the built environment and ensuring that all building developments are net zero carbon aligned. 

The pilot version, launched in September 2024, marks the start of industry-wide testing. It sets limits and targets that help ensure new and existing buildings meet the UK’s climate goals by reducing their carbon impact across the entire building lifecycle.

The need for the Standard and its impact

Before the release of the UK NZCBS, there was no single, agreed-upon methodology for determining what qualifies as a net zero carbon building. This led to confusion and inconsistent claims, often leaving stakeholders unsure of whether buildings were truly aligned with the UK’s 1.5°C climate targets.

The UK NZCBS was created to resolve these issues, offering clarity and technical rigour. Its primary impact will be the reduction of carbon emissions in both new buildings and existing buildings across a wide range of 13 sectors, ensuring the built environment plays its part in achieving net zero carbon by 2050.

Who should use the UK NZCBS?

The standard is designed for a wide range of industry professionals, including:

• Developers and contractors: Ensuring projects meet carbon reduction goals.

• Architects and engineers: Guiding design processes to minimise carbon impact.

• Asset managers and owners: Verifying that their properties align with net zero carbon targets.

• Investors and financiers: Offering confidence that projects are on track to meet long-term climate commitments​.

How it works with other standards and certifications

The UK NZCBS is complementary to existing standards like BREEAM, LETI, and the RICS Whole Life Carbon Assessment Standard. While certifications like BREEAM focus on broader sustainability aspects, the UK NZCBS zooms in on carbon management across a building’s lifecycle. It aligns particularly well with RICS Professional Standard (version 2) in setting out how to perform embodied carbon assessments, creating a seamless bridge between different sustainability certifications​.

Structure and requirements of the UK NZCBS

The UK NZCBS pilot version sets out ambitious but fair limits, targets, and reporting requirements to ensure that buildings are truly net zero carbon aligned. These requirements span multiple aspects of building design and operation, ensuring that both embodied and operational carbon are accounted for.

Limits are set for:

• Upfront carbon: The carbon emissions generated during the initial stages of a building’s life cycle.
• Operational energy: Energy consumption during the use phase.
• Fossil fuel free: Avoiding fossil fuel use on site.
• District heating and cooling networks: Reducing energy demand by using shared resources.
• Refrigerants: Minimising harmful emissions from cooling systems.
• Heating delivered: Ensuring efficient heating systems​.

Targets are set for:

• On-site renewable energy generation: Encouraging renewable energy sources to meet building demands.

Reporting requirements:

• Life cycle embodied carbon: Reporting the total carbon emissions associated with materials and construction processes across a building's entire lifecycle.
• Operational water use: Monitoring and reporting water consumption during a building's use phase.
• Electricity demand: Tracking the building’s total electricity consumption.
• Heating and cooling delivered: Reporting the energy used for maintaining indoor temperatures.

There is also an optional reporting requirement for carbon offsetting, allowing projects to voluntarily disclose offset actions, although the focus remains on minimising direct emissions.

Embodied carbon and RICS alignment

The UK NZCBS places a strong emphasis on embodied carbon, which refers to the greenhouse gas emissions resulting from the production, transportation, and assembly of building materials, as well as their end-of-life disposal or recycling. This type of carbon is generated before a building is even occupied, making it a crucial focus for achieving true net zero carbon alignment.

According to Section 5 of the pilot version, the embodied carbon assessment must include both life cycle embodied carbon and upfront carbon. The life cycle embodied carbon accounts for emissions throughout the entire life of the building, from sourcing materials to demolition, while upfront carbon focuses specifically on the emissions generated up to practical completion.

To ensure consistency and accuracy in these assessments, the UK NZCBS requires them to be aligned with the RICS Professional Standard. This standard, developed by the Royal Institution of Chartered Surveyors (RICS), sets out detailed methodologies for calculating and reporting whole life carbon emissions over the lifecycle of a built asset. By adhering to the RICS framework, the UK NZCBS ensures that embodied carbon assessments follow a rigorous and widely accepted approach, promoting transparency and comparability across different projects and sectors.

Aligning with RICS also strengthens the standard’s credibility, as RICS is a trusted authority in the built environment. This alignment allows stakeholders to confidently measure and report their building’s carbon footprint in a way that is both scientifically sound and industry-accepted, making it easier to meet compliance requirements for net zero carbon alignment.

Next Steps for the UK NZCBS

The pilot testing programme, set to launch in early 2025, will be a critical phase for gathering feedback from real-world projects. The aim is to refine the standard and ensure it is both ambitious and achievable across a wide range of building types.

The final Version 1, expected by late 2025, will include a formal verification process for buildings to be certified as net zero carbon aligned. Additionally, new limits and metrics will be added for:

• Life Cycle Embodied Carbon
• Space Heating Delivered (additional building types)
• Electricity Demand Management
• EUI limits (additional space types)

Acknowledging the Contributors

The UK NZCBS is the result of an immense collaboration from over 350 industry experts, with key contributions from the following organisations:

• Better Buildings Partnership (BBP)
• Building Research Establishment (BRE)
• The Carbon Trust
• Chartered Institution of Building Services Engineers (CIBSE)
• Institution of Structural Engineers (IStructE)
• LETI
• Royal Institute of British Architects (RIBA)
• Royal Institution of Chartered Surveyors (RICS)
• UK Green Building Council (UKGBC)

Their collective effort and expertise have created a robust, scientifically sound framework that will drive significant progress in the UK’s decarbonisation efforts​. We are appreciative of the hard work that goes into developing such a standard and are grateful for its ability to create a clearer path to net zero in the built environment. 

References

• UK Net Zero Carbon Building Standard Pilot Version Document
• UK Net Zero Carbon Building Standard Pilot Version Overview Presentation
• Buildings to prove they are net zero carbon with UK’s first agreed methodology: UK Net Zero Carbon Buildings Standard