The scope and modules of a Whole Life Carbon Assessment

The scope and modules section is where a Whole Life Carbon Assessment either becomes comparable with other schemes or does not. Get the whole life carbon assessment scope modules right and a reviewer can read your number against a benchmark. Get them wrong, by omitting services or stopping at practical completion, and the figure is a number with no meaning, which is how most assessments fail review.

The RICS methodology, now in its second edition, sets the modules, the reference study period and the reporting format. Authorities that ask for a whole life carbon assessment almost always ask for that methodology, and the London Plan requires it for referable schemes.

Life cycle modules and what has to be reported

The modules come from the European standard on assessment of environmental performance of buildings and are grouped into four stages plus one outside the system boundary.

Product stage A1 to A3: raw material supply, transport to the factory, and manufacturing.

Construction stage A4 and A5: transport to site, and construction activities including pre-construction demolition and construction waste.

Use stage B1 to B7: in-use emissions from materials, maintenance, repair, replacement, refurbishment, operational energy and operational water.

End of life stage C1 to C4: deconstruction or demolition, transport, waste processing and disposal.

Module D: benefits and loads beyond the system boundary, covering reuse, recovery and recycling potential and any exported energy.

Three definitions have to be used consistently because reviewers check them. Upfront carbon is A1 to A5, the emissions already released by the time the building is handed over. Embodied carbon covers A1 to A5, B1 to B5 and C1 to C4. Whole life carbon adds operational energy and water, B6 and B7.

Module D is the one that gets misused. It is reported separately and is not subtracted from the whole life figure, because the benefits it records fall outside the building's own system boundary and depend on what someone else does in sixty years' time. An assessment that nets module D off the total to reach a lower headline will be sent back.

Reference study period and why 60 years

The default reference study period for most buildings under the RICS methodology is 60 years. It is a convention rather than a prediction, and its purpose is comparability: two schemes assessed over the same period can be compared, two assessed over different periods cannot.

The period drives the B4 replacement calculation, which is where a lot of the difference between two assessments of the same building comes from. A façade system with a 30 year service life is replaced once within the period, a 25 year system twice. Small changes in assumed service life produce large changes in the result, so state the service life assumed for every major element and the source for it.

Where a shorter period is used, for example on a building with a known temporary consent, say so prominently and give both figures if you can. A 30 year study period produces a lower number for reasons that have nothing to do with the design.

Scope boundaries and what gets excluded

The commonest reason an assessment is rejected is incomplete scope. Four areas are routinely under-reported.

Building services, meaning mechanical, electrical and public health installations, which on an office or a residential block can account for a substantial share of upfront carbon and are often left out because the data is harder to find.

External works: hard landscaping, retaining structures, drainage, boundary treatments and site infrastructure within the site boundary.

Pre-construction demolition and site clearance, which belongs in A5 and is frequently omitted on a redevelopment where it is one of the largest single items.

Temporary works, including piling mats, formwork and propping.

Legitimate exclusions exist and should be stated explicitly with a reason: loose furniture and equipment, tenant fit-out beyond shell and core, and works outside the site boundary. Write them as a list rather than leaving the reader to infer them from a gap in the results table.

Data sources and the quality hierarchy

Use the best data available for each element and say which you used, element by element.

1. Product specific environmental product declarations, third party verified, for the actual specified product.
2. Manufacturer average declarations where the specific product is not yet selected.
3. Sector or industry average declarations.
4. Generic database values.

At planning stage most assessments sit at levels two to four, and that is acceptable provided it is disclosed. What is not acceptable is presenting a database value as though it were a verified product declaration, or using an optimistic figure for a product that has not been specified and is unlikely to be procured.

Record the data source, its reference year and its geographic scope in the materials schedule. A declaration for a product manufactured overseas with a different grid mix is not interchangeable with a domestic one.

Benchmarks and presenting performance

Report in kilograms of carbon dioxide equivalent per square metre of gross internal area, and give the gross internal area used. Then compare against published benchmarks rather than asserting good performance.

Several benchmark sets are in use: the RICS reporting benchmarks, the targets published by the Royal Institute of British Architects, those published by the Low Energy Transformation Initiative, and in London the figures in Greater London Authority guidance. They are revised, so cite the version and the date, and show the comparison as a table or a simple chart rather than in prose.

Be honest where the scheme does not meet a benchmark. An assessment that reports a figure above the aspirational target and explains the three design decisions driving it is more useful, and more credible, than one that finds a benchmark it happens to beat.

Retention and reuse as a saving

Substructure, frame and façade usually dominate upfront carbon, so retention is the single most effective design lever available. Keeping a frame avoids A1 to A3 and much of A4 and A5 for those elements.

Three drafting points.

Set out the retention explicitly in the baseline, showing what is retained and what the equivalent new-build emissions would have been, as a clearly labelled comparison rather than a claimed saving.

Include the emissions that retention does cause: strengthening works, remediation, additional transport, and the longer programme.

Where reused materials come from elsewhere, record the module in which the benefit falls and avoid double counting with module D on the donor project.

A whole life carbon assessment and a circular economy statement draw on the same material quantities, so they should be produced from one bill rather than two, and the figures must reconcile.

Assumptions that move the result most

In rough order of influence on a typical scheme: the concrete specification and the level of cement replacement, the steel route and recycled content, the service life assumed for replaceable elements, transport distances in A4, and the grid carbon factors used for B6.

That last one matters for a reason worth stating plainly. Operational carbon in module B6 depends on assumptions about grid decarbonisation over 60 years, which nobody can know. Use the factors the methodology directs and report B6 separately so a reader can see how much of the total rests on that assumption. The figures should also reconcile with the regulated energy outputs in the energy statement, and with the energy credits in any BREEAM credit strategy.

Submit the results in the reporting template the authority asks for, which in London means the GLA template at pre-application and post-construction stages. Councils expect a suitably qualified author for this work and professional review is strongly advised.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.