Part Z is an industry-backed proposal to amend the Building Regulations to mandate whole-life carbon assessment (WLCA) and, over time, set embodied-carbon limits for major developments. It remains a proposal — not law — but the draft text is clear, aligned to existing methods, and designed to phase in mandatory assessment before limits.
“[Part Z is] a public-facing campaign to show the government that we — the industry — are ready for legislation on embodied carbon… we must legislate for embodied carbon,” said Simon Corbey of ASBP
The RICS whole life carbon assessment (2nd ed.) is in force from 1 July 2024, giving a UK-specific method that covers embodied, operational and user carbon, and requires any deviations to be recorded.
At framework level, EN 15978 (and the emerging EN 15978-1) define the building life-cycle modules and calculation rules used across WLCAs: A (product + construction), B (use), C (end-of-life) and D (beyond system boundary).
The UK Net Zero Carbon Buildings Standard (Pilot) (revised April 2025) provides embodied and operational performance limits many clients are already trialling.
“…we’ve been regulating and measuring operational carbon for a long, long time… and that has brought down those emissions significantly,” said Charlie Law of TDUK reminded the audience.
In July 2025, DLUHC published research on the practical, technical and economic impacts of measuring and reducing embodied carbon in new buildings, an evidence base that supports future regulation.
The London Plan requires whole life-cycle carbon assessments (WLCA) for referable applications, with guidance, templates and a post-construction submission route — an operational model for how WLCA can be run through planning.
Embodied-carbon emissions are material at national scale: around one in ten tonnes of the UK’s total greenhouse-gas emissions are embodied in construction materials and processes — more than aviation and shipping combined — yet there is still no national regulation to reduce them.
Consensus from the panel speakers in three points:
(1) mandate WLCA first, then introduce limits;
(2) build competence across project teams and suppliers;
(3) require verified, machine-readable product data so decisions are fast and defensible.
“Awareness is the first [rung]… but then you need to get competence over time.” said James Cadman of the Supply Chain Sustainability School underlining the need for structured upskilling.
Apply RICS WLCA (2nd ed.) and structure results by EN 15978 modules A–D; record assumptions and any deviations to keep studies comparable across options and suppliers.
Use UK NZCBS Pilot thresholds at RIBA Stages 1–3 to drive early optioneering (form, structure, grid, materials) before costs harden. Treat WLCA like fire safety: non-negotiable evidence at design reviews.
Accelerate design team workflows and procurement comparisons. Enable API ingestion and machine-readable benchmarks in WLCA tools.
Avoid double-counting and make selection decisions defensible against RICS WLCA. Improve comparability across suppliers and streamline tender evaluation processes.
The tools, methods and targets already exist and the policy trajectory is clear. UKGBC’s position is explicit: embodied-carbon regulation is overdue given its national significance. Teams that embed WLCA, require verified product data and align to UK NZCBS targets now will be better prepared — data, supply chains and skills in place — when Part Z (or equivalent) lands.