The Net Zero Carbon Buildings Standard and what it means for Part Z
What is the Net Zero Carbon Buildings Standard (NZCBS)?
The NZCBS pilot version was launched in September 2024. The Standard was written by experts across the UK construction industry to address the lack of a clear, consistent definition of net zero carbon that is aligned with a 1.5°C trajectory within the built environment.
The Standard sets asset-level requirements around various aspects such as embodied carbon, operational energy, renewable electricity generation, and so on. These requirements are based on the construction industry’s allocation of the remaining UK 1.5°C aligned carbon budget (as legally bound by the Paris Agreement). These science-led requirements are set for different building types (new-build, existing and retrofit) within all major building sectors (homes, offices, hotels, sport and leisure, etc.) that together make up the majority of the building stock.
To achieve ‘Net Zero Carbon Aligned Building’ classification in accordance with this voluntary Standard, an asset must meet all the mandatory limits and requirements that it sets out.
Is Part Z still needed then?
In short, yes.
The Standard represents the coming together of the UK construction industry’s expertise to define science-based carbon limits and targets for UK buildings. It is aligned with the Part Z proposal in that it sets limits for upfront carbon, requires the reporting of whole life carbon, and requires embodied and whole life carbon calculations to follow recognised industry standards and guidance documents, principally the RICS methodology within their Professional Standard, ‘Whole life carbon assessment in the built environment’ (2nd ed).
The Standard takes an important first step to bring buildings in line with the 1.5°C carbon trajectory, but as it is voluntary, not all construction projects will aim to comply with it. Ensuring the voluntary standard is implemented will require the backup of regulation, which is why there is still a need for Part Z.
The limits in the NZCBS represent the achievable best practice emissions derived from project data, and these are shown in the graph below. The blue bars show the various aspects of embodied carbon (upfront in dark blue, and life-cycle and end-of-life in lighter blue), while the orange bars show operational energy use. At this moment, only operational energy use is regulated, demonstrating the urgent need to regulate embodied carbon.
Figure 1: NZCBS operational and embodied carbon emissions for Net Zero Carbon Aligned Buildings
NZCBS proving the case for Part Z
Interest around the NZCBS demonstrates the appetite that the construction industry has for consistent reporting and limiting of carbon emissions in our buildings. The assessment and reporting requirements of the Standard builds on the RICS methodology, which has for years now set the UK standard for properly assessing embodied carbon emissions. The embodied carbon limits specified by the NZCBS demonstrate how limits can be set based on data collected from real-world projects. And the figure above shows the important role of those limits in regulating embodied carbon via Part Z.
Ultimately, the NZCBS demonstrates that Part Z is both feasible and required.
The Part Z proposals are consistent with other initiatives globally, which is to measure first, limit later. The Standard proves that both of these things can be done, and the Part Z Authors hope that those in government will now join the dots and move forwards on embodied carbon regulation.