New RICS Guidance: Whole-Life Carbon Assessment for The Built Environment v2

5 min readMar 23


Cercula welcomes the news that the WLCA professional statement from 2017 has been updated with further guidance and consultation from the industry.

There has been a tremendous amount of work that has gone into updating the document from some of the leading experts in the sector. The result is a very well written and comprehensive guide for the industry to carry out carbon assessments across the pipeline of work.

We have more work to do to deep dive into the updates, and there may be further changes after the consultation, but here are a few of the initial changes that stick out to us:

1 — New Modules

The general structure of the modules is the same (A, B, C, & D). However some modules have been added, and some split.

Within the Upfront Carbon Categories (A), the product and construction categories remain unchanged. However there is an additional optional Pre-construction (A0) category that has been added, to capture carbon associated with preliminary studies, tests, acquisition of land and design. This is an optional module and will be ignored in most cases as likely negligible, but in some large infrastructure projects this should be included if significant.

Within the In-Use Carbon Categories (B), embodied carbon and operational carbon modules are unchanged. However a further B8 category has been added to capture carbon from user activities, not included in B6 & B7 (operational water and energy use). Again this is an optional module, and its inclusion will depend on the nature of the project. Scenarios included may the mechanical operation of a plant, FF&E of a building, commuters to an office etc.

Within the Benefits and Loads beyond the system boundary (D), the module has been split into two, to better categorise the negative emissions from processes such as material circularity, or exporting energy to the grid. This has been split by benefits gained from materials (D1), such as materials being reused or burnt and energy captured, and benefits gained from utilities (D2), such as use on site renewable energy exported to grid.

Additionally, biogenic carbon, or the carbon sequestered from timber, has been reported separately in all modules that it occurs in.

Screenshot courtesy of RICS

2 — Better, more granular assumptions for materials

In the first edition of the WLCA, we were given assumptions to use as fall back data, to help fill out all the algebra required to calculate modules. This has now been upgraded, with even more granular assumptions by material type.

If you ask us, this could be made even better by aligning with UniClass codes from NBS (yes we have added this in the comments!).

Screenshot courtesy of RICS

3 — Data quality scores

A question we get asked very often at Cercula is: how do different kinds of data rank in terms of accuracy? Well the contributors of this document have helped us out with an answer. They have created a data quality index (DQI), not unlike the system used to rank datasets in the ICE database. Of course, the system is arbitrary, but it gives us a jumping off point to understanding what data goes where.

Clue > the lower the score, the more assumption heavy, the early in the design process it will be used.

Screenshot courtesy of RICS

4 — Stronger guidance for WLCA when applied to retrofits and refurbishment

The document also provides some good guidance on how to approach retrofits and refurbs. This is a hugely important area of construction to assess, as we need to make sure our upgrade of the building stock makes sense in terms of carbon flows. This is confirmed by the text in the document.

‘All retrofit/refurbishment projects should be treated as new projects and must report against all life cycle stages over the defined reference study period (RSP).’

The scope of analysis is also made clear in terms of the new carbon introduced, and module D.

5 — Guidance on circularity & negative emissions

As previously mentioned, the D categories that deal with circularity and its benefits on the carbon impact of buildings, have been split into two subcategories. This breakdown is key, as this module can become somewhat of a black box when recorded as a single number. It includes many things, such as energy recovered from reused materials, energy recovered from incineration at end of life, and energy exported from the grid.

All of this and how it is calculated is laid out in 4.7 of the guidance, and there is some good detail to help assessors get their heads around this tricky and contentious module. However, we believe there is a lot more to be developed in this area, and it may even go beyond the scope of a WLCA.

Screenshot courtesy of RICS

6 — More Diagrams

The whole life carbon assessment is a lengthy and complex analysis, with a lot of moving parts to mentally juggle. Diagrams and figures give a bit of colour to the maths at play — plus engineers love a diagram!

Screenshot courtesy of RICS

Overall we are pleased to see the progression of the industry guidance, helping the practice of carbon assessment to be more adoptable as a whole. The document also helps tools like Cercula develop and increase functionality for our users. It will be instrumental to our continued development.

We look forward to seeing where this takes the built environment!

The document is available for comments at this link. —