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‘Part Z’ embodied carbon cap tabled by industry group

Stephen Cousins

Industry calls on government to mandate assessment and reporting of whole life carbon on building projects over 1000m2 through Building Regulations by 2027

Mandatory limits on embodied carbon for any building project over 1,000m2 could be introduced by 2027 if a proposed amendment to Building Regulations is adopted by the government.

The ‘Part Z’ amendment, and accompanying ‘Approved Document Z’, was drawn up by a group of sustainability leaders, including the Institution of Structural Engineers (IStructE), the Chartered Institute of Building Services Engineers, the Embodied Carbon Group at Feilden Clegg Bradley Studios, and the Whole Life Carbon Network.

If enacted, it would mandate the assessment and reporting of whole life carbon on all building projects over 1,000m2 from 2023.

The embodied carbon cap, timetabled for four years later, has still to be defined, but according to Will Arnold, head of climate action at IStructE, even a 10% reduction compared to business as usual, would prevent around 2 million tonnes of carbon from entering the atmosphere each year.

Many people already assess whole life carbon on their projects as part of in-house climate commitments and want to see regulation to create a level playing field

‘There's a general consensus in the industry that this is something that needs looking at closely now,’ says Arnold. ‘Many people already assess whole life carbon on their projects as part of in-house climate commitments and want to see regulation to create a level playing field. There is international precedent for this and in the timescales we're talking about the likes of Finland, Sweden, the Netherlands, and France have enshrined embodied carbon into law. The Netherlands has been assessing projects since 2012.’

The group is calling on organisation leaders and heads of sustainability to visit the website and endorse the initiative. Major firms already backing it include architects Allies and Morrison and FCBStudios, main contractors BAM Construct UK and Laing O’Rourke, interdisciplinary engineers Arup, and the property companies Grosvenor and Stanhope.

The proposed amendment comes a month after the Climate Change Committee delivered its 2021 Progress Report to Parliament, recommending that the government set out plans to phase in mandatory whole life carbon reporting and limits for all buildings, roads and infrastructure by 2025.

A major driver for Part Z is the need for regulation to extend beyond operational carbon assessment, says Arnold: ‘We're now at the point where if you build a new, low-energy home, embodied carbon will make up at least 50% of whole life carbon. But you are still permitted to use as much embodied carbon as you want, for example putting large volumes of concrete in the ground or building with a steel frame instead of using timber.’

He adds: ‘Even on projects where operational carbon remains the largest proportion of the total, embodied carbon is released during construction, within the first one or two years of a building’s life, and unlike the installation of a high performance facade or a new heating system to reduce operational carbon, it can’t be clawed back further down the line.’

The likes of Finland, Sweden, the Netherlands, and France have enshrined embodied carbon into law

Around 10% of national greenhouse gases emissions are associated with the construction phase, ie. embodied carbon. Legislation setting out clear requirements to measure, report, and reduce embodied carbon against strict targets could support the government’s roadmap to deliver net zero by 2050 and help demonstrate UK commitments at the COP26 climate conference in Glasgow.

The group asserts that the dates of 2023 and 2027 are achievable based on current industry progress. The UK already has most of the necessary tools in circulation, such as the Royal Institution of Chartered Surveyors’ whole life carbon assessment guidance and a free to use Built Environment Carbon Database, which is in development.

Construction materials make up the bulk of embodied carbon – about 80% – and there are a number of routes to bringing it down, says Arnold: ‘We know that timber has a major role to play in certain types of construction. An easy win in buildings with a wide column grid, such as high spec commercial developments, is simply to position columns closer together because there's a direct relationship between how far apart they are and how much material you need to span that space.’

He adds: ‘Setting a carbon limit, as a metric of carbon per square metre constructed, is the best way to enable design teams, contractors and developers to understand what they need to achieve using existing processes.’


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