This guidance is based on the methodology set out in the RICS Professional Standard (2nd edition) for Whole Life Carbon Assessment. For a WLCA to be compliant with this standard, all relevant mandatory requirements for that project type and phase must be fulfilled.

The reuse and refurbishment of existing structures is often the most efficient approach in terms of WLCA. This approach minimises the need for new materials and reduces demolition waste, typically resulting in a carbon emission benefit over the Reference Study Period (RSP) compared to demolition and redevelopment or new-build. WLCAs help identify significant causes of carbon impacts, integrate carbon into design, and support long-term life cycle thinking. The standard promotes circular economy principles by prioritising reuse and preferring retrofit/refurbishment over new build.

One Click LCA has been officially validated by the Royal Institution of Chartered Surveyors (RICS) under its new Whole Life Carbon Assessment Software Validation Programme. This makes One Click LCA the first software globally to meet the RICS WLCA standard (2nd edition) for generating consistent, transparent, and compliant whole-life carbon assessments.

All modules must be included, namely A1-A3, A4, A5, B1, B2, B3, B4 to C4, D1 & D2). A0 is optional.

"Whole life carbon assessment, RICS - 2nd Edition" allows for both EN15804+A1 and EN15804+A2 data to be used in calculations, using the GWP-fossil impact indicator from the revised standard.

The RICS 2nd edition tool also supports GWP-only data, such as TM65 resources, provided they meet One Click LCA's data quality standards: How One Click LCA Works with Data

For the purposes of a compliant WLCA:

RICS recommends that assessments for a standalone fit-out project, where the shell and core are not affected, to adopt a 10-year RSP. This will highlight the waste that can be associated with typical short fit-out cycles, and to show the benefits of more sustainable fit-out strategies.

The tool is only applicable to all kinds of built assets, including all types of buildings, small projects in the UK and CANNOT be used for infrastructure assets/civil engineering works.

Create a building project and select the tool "Whole life carbon assessment, RICS - 2nd Edition"

Set up your first design and change the LCA parameters to:

NOTE: We recommend disabling the LCA parameter Material manufacturing localisation target.

If you are, however, enabling this, please choose v2.1 (Recommended) and select the Material manufacturing localisation target: "United Kingdom Electricity profile - IEA2022"

This is in the first section of the Pre-Construction tab.

Module A0 covers non-physical pre-construction activities, such as surveys and activities associated with the design of the asset.

These can be a significant economic cost, but for buildings, this do not normally have a significant environmental impact. A0 is therefore generally assumed to be zero for buildings.

In a retrofit/refurbishment project, any demolition/deconstruction or alterations to facilitate the works, including removals and/or stripping out of elements, must be treated as pre-construction works and reported in the separate sub-module A5.1.

This is in the Pre-Construction tab.

Either a scenario or specific inputs are required.

There is only one single scenario for selection, in the section Demolition/Deconstruction scenario - A5.1

If there is specific data for A5.1, please enter these into the following sections:

New material added to the asset must be accounted for.

Retained elements from the original building are also to be accounted. These are assumed to have no impact from their previous manufacture included in the A1–A5 assessment of the refurbishment. These must be marked as Reused material and Locally reused.

Marking the Reused material checkbox will omit the calculation and reporting of A1-A3, as well as, A5 emissions.

Marking the Locally reused checkbox will omit the calculation and reporting of A4 emissions.

Retained elements may result in impacts during the in-use stage, such as from

maintenance or replacement. This is reported in module B; from their end-of-

life impacts, reported in module C; and from potential benefits or loads

outside the system boundary from their recovery, in module D.

The rest of the required inputs are to be adhered to, as of the current guidance for a new building - UK: Whole Life Carbon Assessment, RICS 2nd Edition

Frequently asked questions on the RICS 2nd edition can be found here.
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