Top takeaways from AECOM’s embodied carbon report

A new report commissioned by the Ministry of Housing, Communities and Local Government⁽¹⁾ on the practical, technical and economic impacts of measuring and reducing embodied carbon in new buildings has strengthened calls for a carbon mandate.  

The output of an extensive research project, the AECOM-produced report identifies barriers to standardised, high-quality carbon measuring and reporting and suggests how carbon data and assessments can be made more accessible, consistent and as a result, effective.  

Here are the report’s top findings and recommendations. 

Barriers to assessing carbon

To understand the full picture of carbon assessing in the built environment, including barriers and opportunities, research was conducted to support the report. This covered three areas:  

• Building types and existing carbon benchmarks 
• Reasons for uncertainty in carbon assessments 
• Cost and economic implications of measuring and reducing carbon 

Key findings show there are inconsistencies across carbon datasets and the outputs of carbon assessments. The report suggests this, coupled with variations between carbon tools and their outputs, restricts the development of consistent datasets and, in turn, benchmarks and targets – all of which are essential for reducing carbon in new projects. 

A lack of data on upfront carbon (emissions produced before a building is occupied) and embodied carbon (emissions produced throughout a building’s lifespan, excluding its use) is causing gaps in carbon benchmarks for certain building types too. This is not helped by uncertainty across the industry in whole life carbon assumptions and models, or the lack of a transparent process for validating data used to underpin benchmarks and targets.  

Where transparency exists, data is limited and often London-centric. Together, these issues undermine the comparability of benchmarks and targets and their usefulness in measuring and reducing carbon.  

Environmental Product Declaration (EPD) data for certain building elements also suffer from large gaps. A sample study in the report showed external works, services, and furniture, fittings, and equipment (FF&E) had the poorest EPD data availability. 

Uncertainty within carbon assessments was identified as another major barrier. The report argues there are many sources of uncertainty, including the data inputs, the carbon assessors themselves, carbon tools, and carbon assessment guidance.  

Uncertainties found to have the biggest impact on carbon assessments were building element categories, scope of life cycles modules, basis of data at different design stages, product sourcing (EPDs), and building services modelling.   

Limited capabilities among sector professionals to use carbon tools accurately and recognise opportunities to reduce carbon emissions were also underlined as a barrier.  

Promisingly, the report found that widespread carbon assessments can help to reduce embodied carbon nationally. There is evidence to suggest that the cost benefit of reducing carbon may offset the cost of introducing carbon assessment requirements, although the report points out that further research is required.  

Recommendations for carbon reform

To improve the effectiveness of carbon assessments, and carbon reductions more widely, the report provides several recommendations. These are grouped and summarised below:  

Priority buildings for carbon reduction: Carbon reduction should be prioritised in six building types (low-rise residential, mid or high-rise residential, commercial offices, industrial, education, and ‘other’ buildings). This would aid the development of sector-specific benchmarks, targets and carbon reduction strategies – to be expanded as more data becomes available. 

Improving data consistency and accessibility: Suggested actions for improving carbon data include developing consistent reporting templates to make carbon data collection across sectors more efficient and standardising the scope of data underpinning benchmarks and targets.  

Exploring low-cost life cycle assessment tools for SMEs is also proposed. As is supporting manufacturers to develop carbon data, including government subsidies for EPDs and introducing rules on the level of detail different-sized businesses must provide.  

A three-tiered data tracking approach, progressing from minimum to best practice, is put forward to encourage improvements in the value of carbon assessment datasets.  

Standardising carbon assessments: Establishing a national carbon dataset (possibly including carbon factors) and providing consistent guidance on how carbon tools generate carbon factors would help to standardise carbon assessments. The report says this will reduce uncertainty in national carbon assessment datasets.  

Three scope elements of carbon should also be defined in all carbon assessments. These are: applicable building types, the building element category scope and the BS EN 15987 life cycle modules covered by benchmarks and targets. Further research on the impact functional units (e.g. floor area) have on carbon assessments is needed too.   

Better use of carbon tools: To limit variations in data input methods and results, guidance on how to use carbon tools consistently is advised. This should be supported by a third-party verification process to ensure they are robust. 

Upskilling the industry: The report suggests upskilling the construction industry to capitalise on opportunities to reduce carbon in stages 0 and 1 of RIBA’s ‘Plan of Work’. Developing consistent methodologies to calculate emissions in early design stages, and tools that enable this, is advised. Training investments in whole life carbon, undertaking whole life carbon assessments (WLCAs), and alternative design and construction methods, is also needed.  

Access to green materials: Government and corporate net zero commitments should be developed to make sustainable materials cheaper and more accessible. An insurance playbook would also support new and innovative materials and there is room for incentivising greater timber usage.   

Verifying carbon assessors: The report highlights the opportunity for an agreed definition of qualified carbon assessors. Assessors could be measured by years of experience or an associated professional institution, with a list of competent assessors and carbon assessor training created.  

Carbon reduction is a work in progress

The AECOM report brings much-needed momentum to the argument for a carbon mandate and builds on calls for greater regulation around and investment in carbon data and assessments.  

Ideas supported by the report have been taking root in the past few years, so its arrival is a welcome spotlight.  

For example, the Built Environment Carbon Database (BECD), a pan-industry initiative launched in 2023, has been instrumental to increasing the availability of embodied carbon data for products and assets. The repository could easily provide the basis for a national carbon dataset and shape more consistent, large-scale carbon data collection and assessments as recommended in the report.  

Its data also feeds the BCIS Life Cycle Evaluator, an incredibly important tool that can produce capital, operational and whole life cycle cost and carbon assessments at the same time.  

As highlighted by AECOM, life cycle assessment tools are a crucial stepping stone. The beauty of LCE lies in the opportunity for quantity surveyors and other construction cost consultants to undertake WLCAs with efficiency and ease. The expertise of these professionals in conducting similar cost estimation tasks makes them a natural fit to lead the charge on standardised carbon assessing and become competent assessors too.  

At this stage, the report has given the government and construction sector a priority list. 

It’s now on both shoulders to take advantage of existing tools and recommendations to propel whole life carbon reduction in the built environment forward.  

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^{(1) UK Gov – Consideration of embodied carbon in new buildings – here}