Research and analysis

The practical, technical and economic impacts of measuring and reducing embodied carbon in new buildings: Executive summary

Published 7 July 2025

Applies to England

The construction and use of buildings creates both embodied and operational carbon emissions. Historically, government policies and voluntary efforts from the industry have primarily focused on the reduction of operational carbon emissions of buildings. However, for the UK to reach its 2050 net zero target^{[footnote 1]}, focusing efforts on reducing the embodied carbon of buildings is also critical.

AECOM has been commissioned by the Ministry of Housing, Communities and Local Government (MHCLG) to review and present recommendations for the sector-wide technical, practical, and economic impacts of measuring and reducing embodied carbon. This has resulted in a holistic understanding of the impacts of the widespread adoption of carbon assessments and the current challenges and opportunities facing the industry.

Across the built environment industry, there are large opportunities to track and reduce carbon impacts across new buildings through developing industry skillsets and through consistent methodologies, data, and tools.

Government and corporate commitments to net zero emissions are expected to lower costs and increase the availability of sustainable materials. However, substantial investment is needed in key areas such as training for sustainable design, standardisation of modelling approaches, and consistent carbon assessments using an array of modelling tools, both simple and advanced.

Additionally, AECOM recommends that the government considers how insurance frameworks, innovative materials, and fire regulations contribute to progressing carbon-efficient buildings.

Improving data quality for building materials is vital, and adopting a tiered data tracking approach for carbon assessment datasets will support the UK’s decarbonisation goals. Extensive data collection and analysis of functional units’ impact on carbon assessment results will enable robust benchmarks and targets that mitigate gamification and facilitate informed decision-making across the industry.

Enabling and supporting consistency within carbon assessments is therefore key to supporting new buildings to decarbonise and achieve a sustainable future.

A summary of the key findings and recommendations associated with the technical, practical, and economic considerations for measuring and reducing embodied carbon in new buildings is displayed within the following sections.

Technical considerations for measuring and reducing embodied carbon in new buildings

Summary of key findings and AECOM recommendations from the technical research.

1. There is a lack of consistency in reported carbon assessment outputs:

The variation between the outputs of carbon assessments limits the ability to compare results across different developments. This is a challenge for developing consistent datasets of carbon assessments. In turn, this impacts the development of consistent benchmarks and targets.

AECOM recommendations:

• Develop consistent reporting mechanisms that enable streamlined carbon assessment data tracking.
• In reporting, three scope elements of carbon assessments must be clearly defined: the building type, the building element category scope and the BS EN 15978 and BS EN 17472 life-cycle modules covered by the benchmarks and targets.

2. There is a need to improve the quality of carbon assessments undertaken:

Mitigate misreporting of carbon impacts.

AECOM recommendations:

• Upskill and train carbon modellers to ensure proficiency in carbon assessment methodologies.
• Create a clear definition of a competent carbon assessor, including developing and specifying training and/or experience requirements.

3. There are large gaps in the availability of both product specific EPDs and generic data:

Across a variety of carbon tools, there are gaps in the availability of generic data among common building elements and materials. An assessment of data availability was conducted for a sample of common building materials to identify gaps in EPD data availability. The results of the sampled exercise showed that External Works, Services and Furniture, Fittings, and Equipment (FF&E) building elements exhibited the poorest EPD data availability, possibly due to product complexity and a fluctuating supply chain for building services elements. One third of materials and products sampled lacked UK based EPDs.

AECOM recommendations:

• A UK-based carbon dataset should be created using the carbon data that is currently accessible.
• Coordinate the generation of product and manufacturer specific carbon data across current and planned policies to enable further generation of consistent carbon data. This could include developing systems to support manufacturers in developing carbon data and collating this data centrally to inform generic UK-based carbon databases.
• In the short term, create interim methodologies, such as how CIBSE TM65 is working for building services products, to reduce the gaps in data availability.
• Development of low-cost LCA tools should be explored for use by SMEs to ensure that cost is less of a barrier to generating carbon data.

4. There is a large variation in product carbon results for similar building products:

The large variation found in both the generic and product specific EPDs creates a lack of consistency across carbon datasets. No clear correlation was found between data quality and magnitude of carbon impact.

AECOM recommendations:

• Consistent guidance should be created about how carbon tools should generate carbon factors.

5. There is a lack of consistency across carbon tools:

The variation between carbon tools and their outputs limits the ability for carbon assessment results to be compared. This in turn, restricts the development of consistent datasets, impacting the development of clear, consistent benchmarks and targets. Furthermore, this may encourage gamification and hinder competition within the carbon tool market, as industry will likely wish to utilise the tool that produces the lowest carbon assessment results.

AECOM recommendations:

• Create a consistent methodology for both public and private carbon tools to follow. As a minimum, the following elements should be included in the methodology:
  • Whole life carbon (WLC) module scope.
  • Building element categories scope.
  • Modelling assumptions within carbon assessments.

• Create a third-party verification process of the tools to ensure that they are robust. The verification should, at a minimum, confirm:

  • The data sources.
  • That the calculations are complete in line with the chosen methodology.
  • Confirm the scope of the module and building element category.
  • Confirm the assumptions used.
  • Verify the output format.
• Create consistent guidance about how carbon tools should generate generic carbon factors.

Practical considerations for measuring and reducing embodied carbon in new buildings

Summary of key findings and AECOM recommendations from the practical research.

1. Limitations on the uptake of innovative and emerging products that have lower embodied carbon:

New materials and products do not benefit from economies of scale in the same way as existing well-established products. This causes new products to be typically more expensive than existing materials / products. New and emerging products can have variations in cost due to warranties, associated with contractor risks and insurance. In addition, the cost of producing Environmental Product Declarations (EPDs), hinders the ability of smaller manufacturers to prove their products as lower carbon.

AECOM recommendations:

• Government subsidies and support of both low carbon materials and UK based manufacturing. Support could also be provided for manufacturers in producing carbon data (such as EPDs) for new low carbon products.
• Creation of an insurance playbook, similar to existing methods such as the mass timber insurance playbook, should be created to support new and innovative materials to address insurance concerns. This would enable further adoption of new and innovative materials.

2. Fire risk as a barrier to the use of innovative and emerging products:

Blanket decisions are being made that are associated with perceived fire risk, limiting the development of new forms and construction methods.

AECOM recommendations:

• Greater awareness of the fire regulations and how to ensure fire safety must be incorporated into every project with the support of a fire engineer/specialist.
• Clear provision of fire ratings of all products. For smaller manufacturers, governmental support could help to ensure this is undertaken quickly and consistently.

3. Upskilling of the industry is required to enable the adoption of alternative methods of design and construction such as timber structure:

The current timber structural design code (Eurocode 5) does not cover mass timber structures, such as Cross Laminated Timber (CLT). The lack of official guidance has led to this becoming a specialist service, with few engineers and contractors holding the necessary knowledge. Existing initiatives, such as the Mass Timber Insurance Playbook have proven to successfully address the insurance market concerns of timber.

AECOM recommendations:

• Rescope professional competence to include fire protection systems and their limitations.
• A new version of Eurocode 5 is expected to be released soon, which is expected to detail design guidance of mass timber elements such as CLT. Once the new version is released, it will be necessary to fast-track the knowledge-building phase, which can be achieved through up-skilling programmes supported by both government and professional institutions.
• Continued investment, particularly in training, is required to reduce the skills gap across the board. This includes upskilling the entire value chain, including developers, designers, manufacturers, and contractors.
• Similar to existing methods such as the mass timber insurance playbook, a similar insurance playbook should be created to support new and innovative materials enabling further adoption of these across new construction, whilst acknowledging and addressing insurance constraints.

4. Barriers to widespread access of carbon tools:

Cost and knowledge of carbon tools, including the knowledge required to use carbon tools accurately prevents the widespread uptake of carbon tools, particularly for Small and Medium-Sized Enterprises (SMEs).

AECOM recommendations:

• Work with the industry to increase access to carbon tools and increase knowledge and skill sets across the industry.
• Offer various carbon tool solutions, including free options (similar to Future Homes Hub’s carbon tool (FHH)), to ensure widespread access to carbon tools, particularly for SMEs.

Economic considerations for measuring and reducing embodied carbon in new buildings

Summary of key actions from the economic research.

1. Direct economic impacts of widespread carbon assessments:

A range of demand scenarios were assessed to understand the potential national annual cost for carbon assessments. For the low demand scenario, the estimated mean national costs for carbon assessments were estimated to be:

• Upfront carbon: £0.98 million.
• Embodied carbon: £1.71 million.
• Whole life carbon: £3.91 million.

For the medium demand scenario, the estimated mean national costs were estimated to be:

• Upfront carbon: £8.82 million.
• Embodied carbon: £15.4 million.
• Whole life carbon: £35.3 million.

For the high demand scenario, the estimated mean national costs were estimated to be:

• Upfront carbon: £29.0 million.
• Embodied carbon: £48.0 million.
• Whole life carbon: £105.9 million.

2. Widespread carbon assessments can have a broader economic cost benefit:

Widespread carbon assessments can help to reduce embodied carbon nationally. The Green Book supplementary toolkit estimates the value of carbon as £269/tCO₂e.^{[footnote 2]} This means that the cost benefit of reducing carbon may offset the cost of introducing carbon assessment requirements. However, further research is required to establish the cost benefit of reducing industry-wide embodied carbon across new-buildings through a range of carbon reduction scenarios that are deemed to be achievable.

3. Carbon assessments can create ‘Green Jobs’^{[footnote 3]} within the ‘Green Economy’:

Carbon assessments can form part of the emerging ‘Green Economy’. The outcome of this new economy can create positive job-creation effects, increasing employment and opportunities for people to up-skill into an emerging new niche occupation.

Supporting the emergence of the green economy can also help to offset any negative effects from process innovations or the implementation of new and significantly improved production methods that could lead to technological unemployment because of increasing productivity.

4. There are currently enough suitably qualified carbon assessors to meet some of the projected demand scenarios:

It is estimated that the minimum number of trained, competent, and active carbon assessors in the UK is circa. 80no., though this could range by up to circa. 330no. based on the sensitivity analysis undertaken.

There is currently estimated to be a sufficient number of competent carbon assessors for the majority of the low and medium demand scenarios modelled, although it is cautioned that this result is based on limitations and uncertainty within the economic analysis. There are not enough carbon assessors to meet the high and very high demand scenarios. However, it is likely that where drivers for undertaking carbon assessments increases, the number of carbon assessors would also increase.

It is recommended that a definition of competent or suitably qualified carbon assessors is created which includes recommended training material. The number of competent of suitably qualified carbon assessors should also be tracked.

5. The cost of a carbon assessment varies based on the carbon assessment scope and stage:

Based on the outcomes of an industry questionnaire, the mean costs associated with carbon assessments were:

• Early design stage: £3,700 (158 respondents).
• Design optioneering: £5,200 (157 respondents).
• Upfront carbon: £7,500 (150 respondents).
• Embodied carbon: £8,100 (151 respondents).
• Whole life carbon: £9,600 (150 respondents).

6. Cost effective decarbonisation solutions:

The most cost-effective embodied carbon optimisations were found to be:

• Optimised column gird in lieu of standard column grid.
• Pad foundations based on ground conditions in lieu of pile foundations.
• Optimised rectangular mezzanine office layout in lieu of standard mezzanine office layout.
• Exposed ceiling in lieu of suspended ceiling.
• Hybrid Variable Refrigerant Flow (VRF) system in lieu of VRF with VRF serving Air Handling Unit (AHU) coils.
• Electric arc furnace steel in lieu of blast furnace steel.
• Reused steel in lieu of new steel.
• Hybrid timber steel structure in lieu of steel structure.
• Air Source Heat Pump (ASHP) with fan coil units and mixed mode operation in lieu of VRF with VRF serving AHU coils.

7. There are a number of key challenges to the scalability of decarbonisation solutions which need to be addressed:

The key challenges to the scalability of decarbonisation solutions were identified as:

• Sourcing constraints due to supply chain availability and supplier preference.
• Warranties and insurance.
• Skills shortage, particularly for timber construction.
• Fire regulations.
• Limited availability of both cost and carbon information.

1. The ‘net zero target’ refers to a government commitment to ensure that the UK reduces its greenhouse gas emissions by 100% from 1990 levels by 2050. ↩

2. Based on the central scenario. ↩

3. ‘Green Jobs’ are described as having two main components. First, they are decent, fair, and meaningful jobs, and second, they are jobs which reduce negative environmental impacts. Subsequently, green jobs are defined by the International Labour Organisation (ILO) as jobs that ‘help reduce negative environmental impact ultimately leading to environmentally, economically, and socially sustainable enterprises and economies. ↩