Published on 29 June 2022
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What will it take to decarbonise buildings?

The UK Government’s Environmental Audit Committee has released its report after a year-long inquiry into the sustainability of the built environment. In their evidence to the Committee, Ramit Debnath and his colleagues drew on research concluding that embodied emissions in the construction of buildings must be reduced if the UK is to meet net zero targets.

Little progress has been made in reducing the emissions involved in building materials and processes such as using concrete or making bricks, and in demolition rather than retrofitting buildings. Yet if the UK continues to ignore this embodied carbon, it will not meet net-zero targets or carbon budgets by 2050. The UK Government’s Environmental Audit Committee’s (EAC) latest report – “Building to net zero: costing carbon in construction” –  highlights that the reason for this failure is that there is no legal requirement for the embodied carbon cost of construction to be assessed or controlled.

The key point in its report is the need for a mandatory requirement to undertake whole-life carbon assessments for buildings, as explained below. The EAC requested a clear timeline for the targets to be set by the end of 2022. This policy will incentivise greater retrofitting, the development and use of low carbon materials, and investment in low-carbon construction skills.

In the report, the EAC says: “The UK built environment is responsible for approximately 25% of total UK greenhouse gas emissions. The UK has a legally binding target to reach net zero by 2050 and at COP26 the Government committed to achieving 68% reductions in carbon emissions by 2030. This is only eight years away. There is little government guidance as to how these targets are to be met by the built environment industry.”

Our evidence presented to the EAC shows that there are insufficient incentives to develop and use low-carbon materials. This should be a high policy priority. The Committee concluded it had seen inadequate evidence that the Government promotes the benefits of reusing and retrofitting buildings instead of demolition. However, there are future opportunities for streamlining the supply chain side of low-carbon materials, including mass timber.

The single most significant policy the Government could introduce is a mandatory requirement to undertake whole-life carbon assessments for buildings.[1]  This requirement should be included in building regulations and the planning system. Following the introduction of whole-life carbon assessments, the Government should then develop progressively ratcheting carbon targets for buildings to match the pathway to net zero. This policy would incentivise more significant retrofitting, the development and use of low-carbon materials, and investment in low-carbon construction skills.

Further to the report being published in May 2022, the Committee’s inquiry is now in its next phase exploring the best routes to net zero for the UK’s future building needs – from low carbon materials to policies to minimise the whole-life carbon impact of new buildings. Colleagues including Professor Michael Ramage in the Centre for Natural Materials Innovations (CNMI) are  working with the EAC and partners including Built by Nature and the Laudes Foundation to enable transformative change in the building and construction sector by developing new policy instruments and a data-driven evidence base.

The EAC’s report addresses sustainability in the built environment in five broad themes:  1) accounting methods for embodied and whole life carbon; 2) the use of low-carbon building materials; 3) government procurement of buildings; 4) issues surrounding retrofit and reuse; and 5) the skills and training required to delivered sustainable construction.

One focus is greater emphasis on the whole life cycle carbon assessment of building. The embodied carbon cost of the construction is not required by current policy to be assessed or controlled, other than on a voluntary basis. As a result, the report highlights that no progress has been made in reducing these emissions within the built environment. The construction industry has shown willingness and the capability to undertake whole-life carbon assessments to measure the operational and embodied carbon cost of construction. The standards, methodology and reporting framework exist but the committee noted that rolling out such standards must need revaluation to manage the cost of undertaking such assessments, which should remain minimal.

In addition, the report emphasises that there is availability of low-carbon building products to meet current demand, but there are insufficient incentives to develop and use these

materials. In particular, there are obstacles preventing the uptake of timber products in construction, which was a concern specifically addressed by the Cambridge team. These include issues regarding fire risk and insurance, price volatility, securing sustainable and local supply chains, and addressing skills gaps in the use of timber. The Government has made little progress in addressing these barriers during the last three years.

The Cambridge-led report called for a greater advocacy for material re-use, especially emphasising the role of timber and similar low-carbon materials in a climate-sensitive circular economy.

Our research concluded that Government must develop a coherent, joined-up policy to meet afforestation commitments and the need for commercial plantations to meet the demand for domestic timber in construction. Based on this, the EAC agreed that the UK Government must invest now in further research and safety testing on the use of structural timber. We continue to research streamlining the supply chain of mass timber and nature-based building products in the UK. At the same time, we are engaging with the international community through the United Nations Development Programme (UNDP) and United Nations Framework Convention on Climate Change (UNFCCC) to make the case for low-carbon building materials transition in construction globally.

While the EAC report is a welcome recognition of the issues, the pace of actual policy development remains uncertain. The major public policy test for the UK’s decarbonisation strategy is to significantly and rapidly reduce carbon emissions associated with the construction sector – if the Government wishes to meet its net zero goals.

The Cambridge team includes Dr Ramit Debnath who prepared the evidence base with other members of the Centre for Natural Material Innovation, supported by Laudes Foundation and Built by Nature. Professor Michael Ramage presented the evidence to the Environmental Audit Committee and House of Commons members at the UK Parliament.


[1] https://www.cambridge.org/engage/coe/article-details/618ad91347f47d812f9b599c

Authors

Ramit Debnath

Dr Ramit Debnath

Affiliated Researcher

Dr Ramit Debnath is a Sustainability Fellow at Churchill College, University of Cambridge and visiting faculty associate in Computational Social Science at Caltech. In addition, he is a research associate...

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