Whole life carbon assessment: Why the built environment industry needs a renewed standard to support

Five years can reflect a lot of change in industry thinking. In this article, Fabrizio Varriale, RICS place and space analyst, examines how practice and the importance of whole life carbon has changed. With the new edition of RICS’ Whole life carbon assessment coming into force in July 2024, what are the standard’s major changes and what is its potential for international application?

RICS published the 2nd edition of the professional standard Whole life carbon assessment for the built environment in September 2023. From July 2024, chartered surveyors conducting carbon assessments will be required to follow its method. The new standard has already impacted beyond the surveying profession and will be instrumental in harmonising carbon assessments across the globe.

Development of the first whole life carbon assessment

The 1st edition of the standard was published in 2017 and was established to provide practical guidance on how to conduct assessments in the UK in accordance with EN 15978. The latter is the international standard that sets out the general rules to assess emissions associated with the construction and use of buildings. It establishes key criteria such as the division of the building life cycle into a modular structure.

The professional standard’s original intent in 2017 was to provide a clear methodology that would improve consistency and comparability of results, which was particularly needed for the practice of assessing embodied carbon. In comparison to the assessment of operational carbon, embodied carbon was less standardised and known only to a small niche of the industry.

By establishing rules for consistency together with a set of UK-relevant values for parameters and assumptions, the 2017 edition filled a significant gap in industry knowledge. It has been broadly adopted across the UK by architects and engineers as well as surveyors and became a key UK methodology to assess embodied carbon in construction. As such, it provides a methodological basis for the integration of WLCA in policy. It has been adopted by several local authorities as part of their planning requirements and by the industry-backed Part Z proposal to regulate embodied carbon in construction.

Reflecting on five years of advancing practice

With advancements in practice and the growing importance of quantifying and reducing emissions across the whole life of buildings, the RICS standard required updating and expanding.

The 2nd edition is authored by an even larger group of experts than the previous edition. It comprises a document of nearly 200 pages accompanied by a set of reporting templates. The major changes introduced by the 2nd edition are as follows.

• Expansion of life cycle modules – remaining within the framework established by EN 15978, the new standard provides further subdivision of some modules to better distinguish between sources of emissions.
• Differentiation between buildings and infrastructure – infrastructure assets are now clearly distinguished from buildings and classified via the types used in ICMS 3. The latter is also used to provide a list of elements that is appropriate for infrastructure (while elements in buildings continue to be classified via RICS’ New rules of measurement).
• Differentiation between project types – clear guidance is given on the scope of assessment for different project types, such as new constructions, retrofits, fit-outs and demolitions.
• Introduction of levels of detail and uncertainty factors – as a project progresses, information on material quantities, energy use and carbon intensity becomes more reliable and specific. Thus, the new standard requires different levels of granularity in the calculation and reporting of results, depending on the project stage that the assessment is conducted. For the same reason, a methodology is introduced to account for the uncertainty of data sources, which reduces as a project moves forward. The methodology also requires evaluating the appropriateness and quality of the data sources used in the assessment, yielding an uncertainty factor (as a percentage) that is applied to the resulting carbon emissions.
• Definition of physical boundaries – diagrams are provided to clearly define which parts of a building and its surroundings are expected to be included in the assessment and under which element category.
• Provision of criteria for the selection of carbon factors – a robust process is established for choosing appropriate carbon factors for materials and energy sources, based on the project stage and purpose of the assessment.
• Expansion of requirements and guidance on in-use emissions – clearer and more stringent criteria are included to guide the assessment and reporting of emissions from operational energy and water use, distinguishing between modelled and measured consumption.
• Provision of detailed reporting templates – a set of comprehensive spreadsheet templates is provided to allow communication and sharing of assessment results in a standardised format.
• Development for international application – UK-specific categories and parameters are replaced with content that is suitable for use across the globe.

The need for confidence and harmonisation

The last point is particularly valuable in a world where the comparability of results is extremely difficult. Differences across methodologies in terms of scope, classification, calculations, assumptions and data sources render comparing like for like challenging. This contributes to lowering confidence in the accuracy and reliability of carbon assessments, which can discourage investors and developers to embed carbon assessments into their decision-making processes. It can also make policy-makers adverse to regulating emissions from the built environment based on such ‘unreliable’ methods.

Some degree of diversity across countries/regions is both inevitable and understandable. However, harmonising assessment methodologies is a key component for progressing the decarbonisation of buildings and infrastructure, as recommended by the International Energy Agency in its Breakthrough Agenda report of 2023.

In answer to this need for convergence, in March 2024 RICS presented its Global harmonisation framework for whole life carbon assessment for the built environment at the Buildings and Climate Global Forum in Paris. This document provides a way to map and describe different methodologies across seven key dimensions, based on the assessment structure established in the 2nd edition of RICS’ Whole life carbon assessment for the built environment.

The framework can be used to highlight and resolve the main differences between assessments, as well as help the adoption or development of a national methodology where none exists yet. After all, establishing how to measure and report carbon is the first necessary step to be able to manage and regulate emissions from the built environment.  

Future international collaboration on whole life carbon assessment

RICS will continue develop additional guidance for the professional standard and is collaborating with international partners to progress the adoption and harmonisation of carbon assessments across the globe. This includes involvement in initiatives such as the Built Environment Market Transformation Action Agenda by the World Business Council for Sustainable Development, the Whole Life Carbon Policy Coalition by the UK Department for Energy Security and Net Zero, and the Buildings Breakthrough (specifically on priority action B1: Standards and Certifications) by the Global Alliance for Buildings and Construction.