The campaign to support an industry-led initiative to introduce a new Part Z to Building Regulations that would require assessment of whole life carbon emissions and set limits for upfront embodied carbon for all major building projects is being revamped and re-emphasised by a group of leading industry experts.
As a supporter of the call to regulate embodied carbon through building regulations, RIBA is urging all architects to become involved.
The Part Z initiative has received more than 200 statements of support from across industry since its launch in 2021 and is backed by all of the main construction and professional organisations, including RIBA. The proposed Part Z, and the proposed Approved Document Z (the accompanying guidance) are drafted and ready to be enacted.
Why is Part Z important?
Tim den Dekker, co-author of the proposed Part Z and Associate at FeildenCleggBradley Studios, says that the need for the construction and real estate sector to send a strong message to government to introduce this legislation is now stronger than ever in the wake of last year’s Climate Change Committee report, which said that the UK is diverging significantly from meeting its Net Zero Carbon commitments.
“Economic, financial, social, and political problems globally and locally compete with the climate emergency for our government’s attention," Tim says. "A simple clear message from a unified voice is more likely to cut through this noise and clarify to government the priorities on sustainability for the construction sector."
He continues: “Part Z simply asks for whole life carbon to be measured, and for limits on upfront embodied carbon to be set to encourage some easy changes to the most inefficient designs to bring them within those limits. The proposed requirements are unlikely to pose a barrier to the current government’s 1.5million homes target. We have found the housing sector to be predominantly in support such regulation.”
Meanwhile, Simon Corbey, CEO of the Alliance for Sustainable Building Products (ASBP), says it is now more important than ever for construction professionals to sign up and show their support. It’s known that the Ministry for Housing, Communities and Local Government (MHCLG) has been actively looking at Part Z proposals and is just about to publish a report by AECOM on industry readiness. Simon says that the Embodied Carbon team at MHCLG has indicated that the more signatures the campaign can collect, the more likely the government will take notice and act.
“Economic growth is now top of the government’s agenda and it has indicated innovation as a key component of growth,” Tim adds. “The clear market signal that embodied carbon regulation will send will encourage private investment in the decarbonisation of the construction industry, itself generating the durable long term economic growth that government wants.”
What’s in the Part Z proposal?
Tim details three key aspects of the Part Z proposal:
- Part Z is a proposed amendment to the Building Regulations, which would see the reporting of whole life carbon with limits set on upfront embodied carbon. It would apply to all major building projects of over 1000m2 and/or 10 or more dwellings.
- It is proposed to be introduced no later than 2028, in two phases: report first, and limit later. This aligns with the rollout of equivalent legislation in the EU. The gap between the phases allows data to be collected that can then inform the limits that are set.
- These proposed amendments to the Building Regulations and the Approved Document have already been fully drafted: Part Z is oven-ready and can be written into legislation as per the proposals.
Tim continues: “We would expect the proposed Part Z limits to reflect the need to meet the requirements of Parts F, H, L, O, and any other regulatory constraints – such as the banning of gas boilers – that will have an impact on both embodied and operational carbon. Furthermore, confirming and enforcing compliance with embodied carbon rules should not be further burden on the planning process. In the same way that planning officers do not look at insulation values under Part L or structural integrity under Part A, they must not be expected to review embodied carbon under Part Z. This view is endorsed by the GLA.”
Prior to the General Election last year, a group of professional institutions, including RIBA and the Institution of Structural Engineers, launched a joint policy paper calling for the same regulation to be enacted by the incoming government.
Embodied carbon emissions make up one tenth of the UK’s current annual emissions, but because they remain unregulated in the UK they have barely decreased over the last 30 years despite the efforts of manufacturers to decarbonise products and materials.
Part Z supporters across the construction and real estate industry argue that the industry would respond overnight to regulation, because the necessary standards, guidance and tools are already available. The industry has had a consistent WLCA methodology since 2017 in the form of the RICS Professional Standard: Whole life carbon assessment for the built environment.
They agree with the Environmental Audit Committee’s finding in 2022 that regulating embodied carbon would be the most impactful policy for reducing emissions in the building sector and that it could be an easy win for the UK’s roadmap to Net Zero.
Several European countries – France, the Netherlands, Denmark, and Sweden – have already introduced some form of embodied carbon regulation, and the European Commission has updated the Energy Performance of Buildings Directive to require the reporting of embodied carbon from 2028 and introduces limits two years later.
Find out more about RIBA Academy's Net Zero Carbon course
How does Part Z work with the Net Zero Carbon Buildings Standard and RIBA’s 2030 Climate Challenge?
The UK Net Zero Carbon Buildings Standard (UK NZCBS), launched in its Pilot Version last year, sets asset-level requirements for different building types across the major building sectors (homes, offices, hotels, sport and leisure etc), including operational energy, renewable electricity generation, and upfront embodied carbon. These mandatory requirements are science-led, based on the construction industry’s allocation within the UK’s carbon and energy budgets aligned with a 1.5°C global warming trajectory.
The UK NZCBS and the Part Z proposal are aligned by both setting limits for upfront carbon, requiring the reporting of whole life carbon, and requiring embodied and whole life carbon calculations to follow recognised industry standards and guidance (principally the RICS methodology).
But the Standard remains a voluntary route map to bring buildings in line with the 1.5°C carbon trajectory, Tim says, and further argues that introducing regulation is the only way of ensuring that the entire built environment starts to tackle embodied carbon.
“For Part Z, government would be unlikely to introduce limits at levels as ambitious as those set out in the UK NZCBS. Instead, the authors expect that the mandatory maximum embodied carbon limits would first be set to catch the highest emitting projects, which would find it relatively easy to reduce their upfront embodied carbon emissions through simple changes to the design and/or material substitutions. As such, although the mandatory Part Z limits would be more lenient than those in the Standard, and Part Z would function to steer the whole construction industry towards the 1.5°C carbon trajectory. The Part Z authors argue that the data collected by the UK NZCBS demonstrates that Part Z is not only feasible but required to bring down emissions by the worst offenders.”
RIBA developed the 2030 Climate Challenge to offer architects a stepped approach towards Net Zero on a similar trajectory to the UK NZCBS. It also sets targets for reducing embodied carbon alongside operational energy and potable water. But again, it is a voluntary commitment that would be supported by regulated limits for embodied carbon. The 2030 Climate Challenge targets will be updated in the near future in line with Version 1 of the UK NZCBS when it’s published at the end of the year.
The proposed Part Z also aligns with guidance and recommendations made by the Institution of Structural Engineers (IStructE), the Chartered Institution of Building Services Engineers (CIBSE), the UK Green Building Council (UKGBC) and the Low Energy Transformation Initiative (LETI).
“The Standard 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, ‘Whole life carbon assessment in the built environment’ (2nd ed),” Tim adds.
What is the perspective from developers?
The Part Z proposals have attracted widespread support from the client-side, including some of the largest UK housebuilders, leading commercial developers, tier one contractors and financial institutions. Some have been developing their own embodied carbon reduction strategies and so would welcome Part Z to level the playing field and remove potential competitive disadvantages, and provide clarity and consistency.
Jennie Colville, Head of ESG and Sustainability at Landsec, says the developer has been tracking and reducing upfront embodied carbon in its projects for over 10 years. In 2022 the company increased its ambition to reduce its upfront embodied carbon for its development pipeline to align with its own science-based carbon reduction target.
Many developers have set their own reduction targets, she says, and we are now starting to see some local authorities embedding embodied carbon into planning conditions, but requirements differ across the country.
“The experience of leading local authorities has shown that these policies can have a positive impact, but the details of these policies are inconsistent across the country, leading to costs that are ultimately passed onto the public,” Tim argues. “National regulation would offer the most effective means to put an end to such wasteful behaviour. There is agreement on this by both the Royal Town Planning Institute and the Greater London Authority’s planning team.”
Jennie continues: “Part Z would send a clear message to the industry of the importance of measuring, reporting and reducing embodied carbon and would increase occupier awareness of the benefits of occupying low embodied carbon buildings,” she says. “It would also standardise the process of WLCAs and ultimately set limits for embodied carbon, sending a clear signal to developers for the need for low embodied carbon buildings.”
It's hoped that with mandatory WLCAs costs of undertaking the assessments could reduce as industry understanding of material performance and whole life carbon improves, Jennie says. Tim also points out that the scale of this further investment in training needs following mandatory WLCAs is no different to what has been seen already from industry in the past few years on a voluntary basis.
If done properly, Landsec sees reducing embodied carbon as a way of reducing overall project costs because it is fundamentally about using less materials, prioritising retention, and lean design.
“Measuring, reporting, and reducing embodied carbon will push procurement strategies to evolve beyond traditional time and cost criteria. Carbon considerations will need to be embedded into material specification, the tender process and supplier selection,” Jennie says.
She continues: “This would mean that developers would need to work closely with our contractors and supply chain to obtain reliable information about the embodied carbon of materials, obtained through Environmental Product Declarations (EPDs). As more EPDs are requested, the supply chain will respond; improving the quality of data and embodied carbon limits would further incentivise the market to improve the carbon credentials of all materials.”
Add support to the Part Z proposal.
Thanks to Tim den Dekker, co-author of the proposed Part Z and Associate at FeildenCleggBradley Studios; Simon Corbey, CEO of the Alliance for Sustainable Building Products (ASBP); and Jennie Colville, Head of ESG and Sustainability at Landsec.
Text by Neal Morris. This is a Professional Feature edited by the RIBA Practice team. Send us your feedback and ideas.
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