Planning and climate change guidance: research report issue 3

9 Assessment and Quantification Thresholds

9.1 background

9.1.1. The assessment and management of WLC, as with all environmental impacts, should be proportionate. However, a proportionate approach requires an understanding of the likely magnitude of WLC resulting from a proposed development.

9.1.2. The Scottish Government’s City & Regional Growth Deals Carbon Management Guidance includes the following WLC estimation requirement, stemming from the UK Treasury Green Book:

9.1.3. “The whole life carbon emissions impact from all proposed programmes, policies and projects should be assessed and quantified, e.g. in tonnes of carbon dioxide equivalent. The level of detail will increase from Strategic to Full Business Case, however carbon estimation is expected at all stages (whenever cost can be estimated, so can carbon to a similar degree of accuracy)”^[60];

9.1.4. Although it is possible to estimate the carbon emissions likely to result from any kind of development at the earliest stages, it is reasonable to recognise there could be a threshold below which such emissions may not require to be quantified and reported through the planning process.

9.1.5. This section includes reference to three approaches to proportionate carbon assessment relevant to the planning process.

9.2 Embodied Carbon

9.2.1. In January 2024, a Policy Position Paper signed by several industry bodies (including the UK Green Building Council, the Institution of Structural Engineers, RICs and the Institute of Civil Engineers, amongst others) was sent to UK political party leaders called for the regulation of WLC emissions in the UK.

9.2.2. The paper outlines that despite the significance of embodied carbon emissions, they are unregulated in the UK and legislation to regulate these emissions has successfully been implemented in countries in the UK and further afield, as outlined in Section 7 of this report.

9.2.3. The signatories outline two milestones; one suggesting the introduction of legal limits on the upfront embodied carbon emissions and a second as below:

9.2.4. By 2026: Mandating the measurement and reporting of whole life carbon emissions for all projects with a gross internal area of more than 1000m2 or that create more than 10 dwellings. Essentially, this paper is suggesting a minimum threshold for calculating the WLC impact of building developments of a gross internal area of more than 1000m² or developments that create more than 10 dwellings. This positioning paper aligns with both the CERG proposal for a ‘Net Zero Test’ and the Proposed Document Z as a proposed amendment to the Building Regulations, both of which consider the need for specific thresholds as described in more detail in Section 6. It also aligns with The UK Green Building Council’s ‘Net Zero Whole Life Carbon Roadmap for the Built Environment – Summary for Policy Makers’ as explored in Section 4 of this report.

9.3 Moray Council Carbon Guidance for Planning Applications

9.3.1. The Moray Council ‘Carbon Guidance for Planning Applications and S36 and S37 Consents’^[61] provides guidelines to support the development management process in determining planning applications. The Guidance is aligned with NPF4 Policy 2a) and 2b) by ensuring developments meet the need of current and future climate scenarios and have given consideration to whole life carbon management.

9.3.2. The Guidance requires a quantitative whole life carbon assessment to be carried out for development where certain thresholds have been met or exceeded and encourages alignment with a “nationally recognised assessment method”. It also requires a carbon management and reporting plan, a carbon sequestration statement, a renewable energy and heat decarbonisation statement, and ‘barriers to net zero’ statement. The document provides detailed questions and requirements under each of these sections to ensure that the development proposals are sited and designed to minimise WLC emissions as far as possible and adapt to current and future risks from climate change in line with NPF4 Policy 2.

9.3.3. The Guidance applies thresholds for which these requirements should be included in the application. The thresholds where the Guidance applies are:

• Residential developments of 10 or more units.
• Commercial, industrial, retail, leisure, infrastructure developments where floor space is 1,000 square meters or more.
• Energy-related developments of 5MW or more.

9.3.4. For developments above these thresholds, evidence of a quantitative whole life carbon assessment and carbon management plan along with statements outlined above is required. These thresholds align with the policy positioning paper outlined in Section 8.2 above and provide additional thresholds for developments in the energy industry which would encompass Scottish onshore and offshore wind developments for example.

9.4 Greater London Authority Whole Life Carbon Benchmarks

9.4.1. Within the Greater London Authority’s ‘Whole Life Cycle Carbon Assessments’ guidance document, benchmarks for a variety of building development types are included to inform planning applicants as they proceed through the planning process.

9.4.2. The whole life carbon (WLC) benchmarks are recommended to be used as a guide for all applicants that are developing projects such as offices, residential developments, educational facilities, and retail developments. The benchmarks provide a range of WLC emissions in kilograms of carbon dioxide equivalent per metre squared (kgCO₂e/m²) and are broken down into lifecycle stages. They also include a percentage breakdown of a typical development for each lifecycle stage.

9.4.3. Projects with WLC emissions higher than the benchmarks are required to “carefully examine how they can reduce WLC emissions” and the assessment template, providing within the Guidance to be used by applicants in the planning process, provides space for applicants to explain any variance and steps they have taken to mitigate WLC.

9.4.4. As well as this benchmark, an ‘aspirational’ WLC benchmark has been set for each development type and lifecycle stage. These stretching benchmarks are based upon a 40 per cent reduction in WLC emissions from the first set of benchmarks, in line with the World Green Building Council’s target to achieve a 40 per cent reduction in WLC emissions by 2030^[62]. Applicants are encouraged to consider how they can achieve WLC reductions in line with the aspirational benchmarks and document this within the planning process.

9.5 Institute of Environmental Management and Assessment Guidance

9.5.1. In Section 4 of this report, the Institute of Environmental Management & Assessment (IEMA) ‘Guide for Assessing Greenhouse Gas Emissions and Evaluating their Significance’ is explored. This guidance document sets criteria for evaluating the significance of whole life carbon emissions impact.

9.5.2. The Guidance emphasises that all carbon emissions are significant and encourages contextualising a project’s carbon impact against pre-determined carbon budgets for example:

• Sector-based carbon budgets;
• Local carbon budgets; and
• National carbon budgets.

9.5.3. The Guidance explores examples of various projects and how they would consider the significance of their carbon impact. It also sets out principles for assessment including all material direct and indirect emissions which are defined by magnitude.

9.5.4. IEMA include an exclusion threshold for significance in Section 5.3 of the Guidance, as follows:

• Activities that do not significantly change the result of the assessment can be excluded where expected emissions are less than 1% of total emissions, and where all such exclusions total a maximum of 5% of total emissions.

9.5.5. This guidance can be interpreted as to where a proportion of WLC emissions (for example construction related or end-of-life emissions) is less than 1% of the total carbon emissions impact of a project, positive or negative, the proportion could be scoped out of an assessment. However, this exclusion threshold is purposefully low to ensure significant emissions are included in any assessments.

9.5.6. IEMA’s approach to carbon quantification and assessment is similar to that proposed by CERG in the form of a ‘net zero test’, as explored in Section 6 of this report.

9.6 Thresholds for Infrastructure Developments

9.6.1. It should be noted that the Policy Positioning Paper in Section 9.2 above is specifically targeted to buildings and due consideration must be given to applying a similar threshold approach to other infrastructure developments.

9.6.2. PAS 2080:2023 sets out guidance for estimating and managing whole life carbon but it is not prescriptive regarding thresholds for carbon assessment. Metrics are starting to be used by infrastructure professionals that could be applied to a wider range of infrastructure projects, such as a kgCO₂e per metre of linear infrastructure (e.g. electricity network, rail, pipeline, etc), although these metrics are currently not widely adopted.

9.6.3. However, it is possible to interpolate a broad threshold value from the buildings embodied carbon policy paper and the Moray Council approaches described above as an indicator of a scale of carbon emissions below which quantification may not be proportionate. The threshold value of 1000m² is used in both instances, i.e. whole life carbon (including embodied carbon) should be assessed for developments larger than this threshold.

9.6.4. The Low Energy Transformation Initiative (LETI) Climate Emergency Design Guide^[63] (further explored in Section 4 of this report) was produced in 2021 by a network of over 1,000 built environment professionals, comprising developers, engineers, housing associations, architects, planners, academics, sustainability professionals, contractors, and facilities managers. It included an ‘Embodied Carbon Primer’ that set out a range of carbon targets for buildings, based on improvements on ‘business as usual’. Embodied carbon values for business as usual (in 2021) ranged from 800kg/m² for residential developments to 1000kg/m² for Commercial developments.

9.6.5. This information may be used to infer that the threshold of 1000m² included in the Moray Council guidance and the Embodied Carbon Position Paper relates to an embodied carbon value of around 800,000kg to 1,000,000kg of carbon dioxide equivalent, i.e. 800 to 1000 tonnes of carbon dioxide equivalent. This may be a logical starting point for the development of a threshold above which formal whole life carbon assessment and management could be required to satisfy NPF4’s climate change mitigation requirements.

9.6.6. To provide some context, the following development types would result in the release of at least approximately 1,000 tCO2e of embodied carbon ^[64]. These proxies should not be regarded as definitive and they are only provided to assist in conceptualising the scale of developments and potential WLC emissions:

• 1,000 m² commercial building;
• 0.5 km of dual carriageway;
• 0.5 km of ballasted railway track; or
• 10km of a stepped one-way cycle lane.