ASBP responds to RICS Whole Life Carbon Assessment second edition consultation

The RICS Whole Life Carbon Assessment (WLCA) aims to become the world-leading standard for carbon measurement in the built environment.

The second edition is currently out for consultation and builds upon the success of the existing RICS WLCA, which aims to establish a global benchmark for consistent carbon measurement at all project stages. We recently held a webinar with Simon Sturgis, one of the main authors of the guidance, to find out more about the updated version and ask questions (click here to watch the recording).

We welcome the work of RICS in developing the important guidance but have some acute concerns with specific elements of the document. We will be submitting a response to the consultation taking into account the comments listed below. We encourage all ASBP members to submit their own response by the deadline – 18th April 2023, 23:59 BST.

Find out more about the consultation and submit your own response at:


ASBP response to RICS WLCA second edition

The ASBP is a materially agnostic organisation that aims to promote ever greater and more demonstrable sustainability across the entire material and product mix within the built environment.

Module D

The scope of the assessment in the introduction (section 1.2) appears at odds with the description in section 2.1 (The modular structure of whole-life carbon reporting). Section 1.2 states “Module D is part of a WLCA, but must always be reported separately” whereas section 2.1 states “Whole-life carbon: modules A, B and C. This is the system boundary for a full carbon assessment over the asset’s life cycle. Note that whole-life carbon does not include modules D1 and D2”.  The importance of module D should not be understated.  Without fair reference and inclusion to module D, it is difficult to see how the guidance can help promote circularity and the best end-of-life outcomes.

It is vital that the narrative throughout the guidance reflects a consistent approach to the importance of module D.  In many sections, this is the case but in other sections there is a danger that “optional” is taken as a euphemism for unimportant, unnecessary and even irrelevant.  Many ASBP members would argue that they would be doing themselves and their clients a significant disservice if their work did not include a credible analysis of module D.

Biogenic Carbon

It is not the role of the guidance to suggest what difference is made if biogenic carbon is included in targets for embodied or whole life carbon.  The role of the guidance is to provide a framework for objective analysis. Whereas sequestered biogenic carbon is balanced within A-C, it may have a bearing on module D and influence end of life choices so suggesting it makes little difference is inappropriate.  The introduction makes clear that module D is included in the WLCA albeit reported separately so limiting comments to A-C is not appropriate. Comments of this nature create a bias in what aims to be an objective methodology.

Comments in section 3.14.1 including a reference to “perverse incentives” with regard to timber could easily be viewed as conjectural or biased and in themselves help create unintended consequences.  All resources are valuable and prone to over-use or exploitation.  A materially agnostic approach is essential if this guidance is to have credibility.  The guidance is explicitly not a policy vehicle so the sector and material specific comments contained in this section should relate to aspects of the modules in question.

In reality, the methodology within the guidance contributes to a “perverse incentive” where it is more beneficial to incinerate timber for energy at the end of life rather than re-use it (see examples 2a & 2c Appendix J), effectively turning the waste hierarchy on its head.

The ASBP is making an appeal to reason regarding the treatment of biogenic carbon in particular at the end-of-life stage (section 3.14.1). Giving a false equivalence between biogenic carbon in a material being reused and the substituted product gives no net value to the carbon being sequestered in the reused material. The problem is compounded when value is given to the calorific content of biogenic carbon at the end of life. This means that there is value in burning biogenic carbon at the end of life but less value in reusing it. This is illogical and as we have mentioned, turns the waste hierarchy on its head.

The motivation behind reusing/recycling is assumed to be the same regardless of the material in question. The motivation to recycle bio-based materials such as timber is different to non-bio-based materials such as concrete and steel so the replaced material assumptions in module D should be different. A tonne of steel or concrete is reused/recycled to prevent a tonne of virgin steel being produced. However, a tonne of timber isn’t reused/recycled to prevent the creation of a tonne of virgin timber or to prevent the planting of new trees. Timber is reused/recycled to enable the sustainable growth of new trees and the production of virgin timber for other end-uses.

In order to rebalance the biogenic carbon anomaly, the ASBP suggests that the biogenic carbon in the replaced material should not be included in module D as an emission and there should be a weighted value placed on the biogenic carbon retained in a reused material. Dynamic LCA has provided a sensible basis – The Batty & Scarr white paper of April 2023 “Does a life cycle carbon assessment constrain the benefits of biogenic materials?” is very informative –

Acronyms & Glossary

The acronyms and glossary sections should be expanded to include all acronyms in the document.  For instance, there are a number of acronyms such as MMR, EoW, EVMS and EER that are not explained.

Carbonation of CaO and Ca(OH)2

The degree and rate of carbonation depends heavily on the exposed surface given that it is largely a surface effect until the point where the concrete is broken or crushed greatly increasing the exposed surface area. Careful consideration must be given to modifications to the exposed surface (coatings) and the dimensions of the concrete element. Recarbonation in service is largely confined to the outermost mm of the concrete element which is governed by the exposed area to volume ratio. This must be clearly reflected in the guidance to ensure recarbonation is not overstated.

General Comments

There is mention of peer review regarding certain data aspects but no mention of peer review for the guidance itself. It would be helpful to understand the peer review process for the guidance prior to publishing. This would also build confidence in the second version when it becomes available.

There is much mention of steel, concrete and timber in the guidance but very little mention of other widely used construction materials such as glass and plastics.

If you have any queries about our response, please contact Simon Corbey, Director, ASBP –

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