As the UK intensifies its efforts to achieve net-zero carbon emissions by 2050, the construction industry is under increasing scrutiny. A significant contributor to carbon emissions, the sector is now focusing on not just operational emissions but also the embodied carbon—the emissions associated with building materials and construction processes. Enter Part Z, a proposed addition to the UK Building Regulations aimed at addressing this very issue.​
What is Part Z?
Part Z is a proposed amendment to the UK Building Regulations that seeks to mandate the assessment and reduction of embodied carbon in construction projects. Embodied carbon refers to the greenhouse gas emissions generated during the extraction, manufacture, transportation, and installation of building materials, as well as during construction and eventual demolition.​
While not yet legally binding, Part Z has garnered substantial support from industry leaders, including the Royal Institute of British Architects (RIBA), the Institution of Structural Engineers (IStructE), and the UK Green Building Council (UKGBC). The proposal aligns with existing standards such as BS EN 15978 and the RICS Whole Life Carbon Assessment for the Built Environment.​
Why is Part Z Important?
Traditionally, building regulations have focused on operational energy efficiency—how much energy a building uses during its lifetime. However, as buildings become more energy-efficient, the proportion of total emissions attributable to embodied carbon increases. Addressing embodied carbon is therefore crucial for achieving comprehensive carbon reduction goals.​
Part Z aims to fill this regulatory gap by:​
- Mandating Whole Life-Cycle Carbon Assessments: Requiring developers to evaluate the total carbon emissions associated with a building, from material extraction to demolition.​
- Setting Embodied Carbon Targets: Establishing benchmarks for acceptable levels of embodied carbon, encouraging the use of low-carbon materials and construction methods.​
- Promoting Transparency: Ensuring that carbon assessments are publicly available, fostering accountability and informed decision-making.​
Proposed Implementation Timeline
According to discussions and studies, the proposed timeline for Part Z’s implementation is as follows:​
- 2023: Begin assessments for non-domestic buildings.​
- 2025: Extend assessments to domestic buildings.​
- 2027: Introduce mandatory embodied carbon targets.
This phased approach allows the industry to adapt gradually, developing the necessary tools and expertise to comply with the new requirements.​
Industry Support and Local Initiatives
Several local authorities have already taken steps to incorporate embodied carbon considerations into their planning policies. For instance, the London Plan Policy SI 2 requires major developments to conduct Whole Life-Cycle Carbon Assessments. Similarly, other councils are exploring policies to mandate embodied carbon assessments and set reduction targets.
These local initiatives demonstrate a growing recognition of the importance of embodied carbon and set a precedent for national regulation through Part Z.​
Conclusion
Part Z represents a significant step toward holistic carbon management in the UK’s built environment. By addressing the often-overlooked emissions embedded in construction materials and processes, it complements existing energy efficiency measures and moves the industry closer to net-zero goals.​
While still in the proposal stage, the widespread support for Part Z suggests that its principles may soon become integral to UK building practices. Stakeholders in the construction sector should stay informed and begin preparing for these forthcoming changes.​
