UK Building Regulations Part Z: What It Means for Whole-Life Carbon and Embodied Carbon Reporting

The proposed UK Building Regulations Part Z amendment - an industry-proposed amendment to the Building Regulations 2010 - would make whole-life carbon assessment and embodied carbon reporting mandatory for significant new construction projects for the first time. If enacted, Part Z would move embodied carbon from voluntary best practice into statutory compliance, reshaping how carbon performance is measured and documented across the UK built environment.

What Part Z Would Require

UK Building Regulations Part Z is designed to embed whole-life carbon accountability into the UK regulatory framework. Under the proposal:

• Developers would be required to assess and report whole-life carbon emissions – covering embodied emissions associated with material extraction, manufacture, transport, assembly, and end-of-life – for buildings over a defined threshold (e.g., >1,000 m² or >10 dwellings). 
• Embodied carbon limits, including caps on upfront carbon emissions, would be introduced over time, with the aim of driving measurable reductions across major projects. 
• The amendment would shift embodied carbon reporting from optional industry guidance to a legal requirement, signalling a stronger regulatory commitment to lifecycle decarbonisation. 

By legislating what many in the sector already consider best practice, Part Z is positioned not just as carbon reporting, but as a catalyst for transparency and performance improvement across design, procurement and supply chains.

Why Part Z Matters for Developers, Designers and Asset Owners

Although Part Z is not yet regulation, it has garnered substantial support from professional bodies and industry stakeholders, including RIBA, UKGBC, CIBSE, and others advocating for regulatory action on whole-life carbon. 

Embodied carbon – emissions tied to materials and construction – currently lacks national regulation despite accounting for a significant portion of a building’s lifecycle footprint, prompting calls from Parliament’s Environmental Audit Committee and industry leaders for mandatory whole-life carbon assessment. 

Part Z also sits alongside broader UK policy signals aimed at reducing whole-life carbon across both new and existing assets, including the growing emphasis on Retrofit First approaches within London planning policy.

Why Part Z Matters for Designers and Developers 

From a practice perspective, Part Z presents both a challenge and an opportunity: 

• It codifies embodied carbon accountability into regulation, creating a level playing field across projects and design teams. 
• It will elevate the importance of early decision-making in design and material selection, where the greatest embodied carbon reductions are realised. 
• It aligns regulatory compliance with emerging investment, leasing, and corporate net-zero commitments that increasingly prioritise low-carbon assets. 

Organisations that have already embedded whole-life carbon workflows will be better positioned to adapt as Part Z moves toward implementation.

Thornton Tomasetti’s Perspective on Embodied Carbon

At Thornton Tomasetti, we have long recognised the strategic value of integrating whole-life carbon thinking into project design. Our embodied carbon expertise combines advanced lifecycle assessment (LCA) methodologies with multidisciplinary engineering insight to help clients reduce embodied carbon, meet evolving regulatory expectations, and secure competitive advantage. 

Recent work – including Stonecutter, one of the lowest reported embodied carbon buildings in the City of London – demonstrates how early material decisions can reduce lifecycle emissions while meeting commercial and design objectives. 

We have supported clients in developing embodied carbon baselines, sensitivity analyses, and design strategies that align with both voluntary benchmarks (e.g., RICS Whole Life Carbon Assessment) and expected regulatory frameworks, including the London Plan’s Whole Life-Cycle Carbon Assessments guidance and Circular Economy Statement requirements. This positions us well to support project teams navigating Part Z reporting and compliance – whether through material optimisation, structure-type evaluation, or early-stage carbon planning.

Looking Ahead: Part Z and the Future of Carbon Compliance

As Part Z progresses from proposal toward potential adoption, embedding robust whole-life carbon assessment workflows will no longer be optional for UK projects – it is fast becoming a regulatory and commercial imperative. 

For organisations preparing for this transition, partnering with experienced advisors who understand both the technical requirements and strategic implications of embodied carbon regulation will be critical.

Prepare Your Projects for Future Embodied Carbon Requirements