Understanding Part Z: What whole-life carbon regulation means for UK construction

Part Z and whole-life carbon regulation in the UK

What is Part Z? 

Part Z is a proposed new section of UK Building Regulations that would require developers to assess and report the whole-life carbon emissions of new building projects exceeding 1,000 m² or comprising more than 10 dwellings, and later to comply with embodied carbon limits. It emerged as an industry-backed solution to address the roughly 20% of UK carbon emissions that come from embodied carbon in construction. Under Part Z, all projects above a certain size would need to perform a whole-life carbon assessment and disclose their embodied carbon; over time, projects would also have to meet specified carbon caps for materials. In short, if enacted, embodied carbon accounting would move from voluntary best practice to a legal requirement.

Why Part Z? 

The rationale is clear: the UK’s operational building emissions have long been regulated (e.g. via Part L for energy efficiency), but emissions from manufacturing and constructing buildings have been largely unregulated. With the UK committed to net-zero by 2050, policymakers and experts agree that tackling embodied carbon is essential. In fact, Parliament’s Environmental Audit Committee called mandatory whole-life carbon assessments “the single most significant policy” to help decarbonize construction. Part Z is designed as that policy “easy win” — aligned with existing industry standards (RICS, RIBA, IStructE, LETI, UKGBC) — to rapidly scale up measurement and reduction of construction emissions. A private member’s bill inspired by Part Z has even been tabled in Parliament, proposing that from 2025/2026 all large projects must report whole-life carbon, with embodied carbon limits kicking in by 2027–2028.

Scope of Part Z 

Initially, reporting would apply to bigger developments (e.g. >1,000 m² or >10 dwellings). The proposal is to start with requiring data collection (to build up benchmarks) and later enforce carbon limits once the industry has experience with reporting. These limits would focus on "upfront" embodied emissions, encompassing the product and construction stages (modules A1–A5). . For manufacturers, this phased approach means an increasing expectation to supply accurate carbon data now, and encourage the reduction of embodied carbon in their products over time.

The evolving regulatory & market landscape 

Part Z isn’t happening in isolation — it’s part of a bigger trend in decarbonization in construction. Across the UK and internationally, regulations and client demands are converging on one point: prove your carbon numbers, then cut them. Key developments include:

UK initiatives: 

Even ahead of national regulation, market drivers are pushing transparency. The voluntary UK Net Zero Carbon Building Standard launched in 2023 already requires whole-life carbon LCAs for new buildings and favours projects using EPDs for materials. Major developers like British Land now perform embodied carbon assessments on every project — meaning they ask suppliers for product carbon data on every bid. Meanwhile, the Greater London Authority requires whole-life carbon (WLC) assessments for referable projects, and other local authorities are following suit. 

UK Carbon Border Adjustment Mechanism (CBAM): Set to be introduced in 2027, aims to align imports with domestic sustainability standards by imposing tariffs on products with high carbon footprints, encouraging fair competition.

The London Plan: The London Plan sets strategic guidelines for development in Greater London, emphasising sustainable construction and carbon reduction. It includes requirements for whole-life carbon assessments (WLCA) for major developments and promotes the use of low-carbon materials and energy-efficient designs. The Plan establishes benchmarks for embodied carbon emissions and encourages compliance with net-zero goals.

European Union: 

The EU is moving rapidly on embodied carbon. Level(s), the EU’s sustainable building framework, provides a common language for reporting whole-life performance, and policies are catching up. The EU is revising its Construction Products Regulation (CPR) to require digitized environmental data for products, and the new Ecodesign for Sustainable Products Regulation will introduce Digital Product Passports for transparency. In fact, European law will soon require verified digital EPD data for key construction materials — starting with high-impact products like steel and cement, and expanding to others by 2040. The EU’s Energy Performance of Buildings Directive is also set to mandate that all large new buildings conduct whole-life carbon assessments by 2028 (and all new buildings by 2030). The message is clear: to sell in the EU market in coming years, a manufacturer must have an EPD for their product. This creates a “pull” effect in the UK as well, since many UK-based manufacturers export to Europe or compete with European products.

Carbon Border Adjustment Mechanism (CBAM): Aims to prevent carbon leakage to locations outside the EU due to increased sustainability requirements. Cleaner industrial production is thus promoted also outside EU by ensuring a fair price on the carbon emitted during the production of carbon-intensive goods.The system enters the test phase in 2025.

Global trends: 

Around the world, embodied carbon is entering the policy mainstream. Several countries already require it — for example, France’s RE2020 law mandates an LCA and an EPD for every new building material used in construction, and the Netherlands and Nordic countries have set carbon limits for new buildings. In the United States, “Buy Clean” regulations are being adopted, which tie public procurement to the carbon footprint of materials. Buy Clean is a procurement approach that sets low-carbon requirements for government-purchased construction materials — for instance, California now requires EPDs and GWP limits for concrete, steel, asphalt and glass in state projects. Moreover, the Corporate Social Responsibility Directive (CSRD) is amplifying the pressure: major construction clients and public companies face disclosure rules for supply chain (Scope 3) emissions, and they in turn demand data from manufacturers. As one RICS expert noted, companies are being “pushed by…reporting directives” — every company will need to report CO₂ emissions in a standardized way. All these forces create a new normal where construction product data on carbon is expected.

Bottom line: 

The direction of travel is unmistakable. Whether via Part Z or other mechanisms, whole-life carbon accounting in construction is becoming mandatory across many regions. Manufacturers who anticipate these construction carbon regulations will be best placed to thrive in a low-carbon economy.