Built Intelligence

What Whole Life Carbon Assessment Targets are there in the UK? By Darren Evans

What Whole Life Carbon Assessment Targets are there in the UK? By Darren Evans

There is a limited range of voluntary assessment schemes that can be used to set whole life carbon targets for UK construction projects. At the time of writing, embodied and whole life carbon do not form part of national building regulations. For anyone looking to adopt a whole life carbon target, therefore, the following two main schemes are used by the UK construction industry.

  • RIBA Climate Challenge 2030.
  • LETI Design Targets.

Both feature targets for embodied carbon. By also taking into account operational carbon, it is possible to assess a project’s whole life carbon.

There are whole-building assessment schemes that include embodied carbon as part of meeting a definition of ‘whole life net zero’. For the purposes of this blog post, we are only considering schemes that actually assess embodied carbon, and which can then be used to produce a figure for whole life carbon – whether the ultimate aim is net zero or not.

Why are whole life carbon assessment targets set?

Broadly speaking, the construction industry has got better at reducing the operational carbon of buildings, which means embodied carbon is responsible for a greater proportion of lifetime emissions. There is therefore increasing awareness of the contribution that embodied carbon makes to a building’s total emissions over its useful life. 

Seeking to factor embodied carbon alongside operational carbon might therefore be a personal choice for a client. Where the client is a larger organisation looking to reduce its environmental impact, they might have a defined embodied carbon reduction to aim for as part of their own policies.

Alternatively, a whole life carbon assessment might be a local planning requirement. This is already the case with the Greater London Authority for certain projects. In time, it is expected that embodied carbon and whole life carbon assessment will become a formal part of national building regulations.

How mature is whole life carbon assessment in the UK?

A document produced by LETI, working with other groups including RIBA, acknowledges that “a key issue the industry faces is the lack of consistent measurement, leading to mis-aligned benchmarks, project targets and claims”.

Despite initial differences in the scope of reporting, a lot of work has gone into aligning the LETI and RIBA schemes. Part of that work has included the creation of a rating system (similar to that used for energy performance certificates (EPCs) or home appliances) to aid comparison. Both targets also assess buildings by type (office, residential, retail, education).

Nevertheless, some difference remains, with LETI’s targets relating to the building at design stage, and RIBA’s when a project has been constructed.

A familiar letter rating system, ranging from A++ to G, allows for a consistent industry approach. Simple comparisons can be made between buildings. It is also more straightforward to set targets and encourage conversations about how to achieve those targets.

The figures that underpin those ratings, however, are based on the amount of carbon per square metre of usable floor area (kgCO2e/m2). This is where the detail of assessments is found.

Basing the result on usable floor area encourages efficient design. An atrium is a good illustration of why this works. The materials used to construct a highly glazed atrium will most likely be carbon intensive, for the gain of relatively little usable floor area.

At the same time, an atrium might offer building performance advantages, such as by providing daylight to areas of the building that would otherwise struggle to receive it. This can save on artificial lighting use, which is part of the operational carbon emissions. A whole life carbon approach allows for this kind of analysis, rather than looking at operational or embodied carbon in isolation.

When should assessments be done to help meet whole life carbon targets?

Like all forms of mandatory and voluntary assessments, the best time to start looking at whole life carbon is in the early stage of projects. As more local planning authorities follow the lead of the Greater London Authority and start to adopt carbon targets as part of planning policy and approvals, early-stage assessments will become increasingly common. 

The key to meeting targets is then following up with further assessments as the project progresses.

When detailed design and specification decisions haven’t been made, generic materials are likely to be assumed as a placeholder. If these assumptions aren’t updated (or accurate data added, where no assumption was included) as decisions are made, the original assessment becomes increasingly inaccurate. 

A whole life carbon calculation that hasn’t been refined doesn’t contribute to the industry’s efforts to achieve ‘best practise’. And for individual projects, it could even mean being found in breach of planning approvals.

Another advantage of early assessment is that it gives designers and specifiers time to assess what information is available to inform decisions about products. EPDs are not ubiquitous, so information can be hard to find.

In some product sectors, even where manufacturers offer EPDs, the level of reporting in different ones may not be the same. Some EPDs report product impacts across all modules; others across only a limited selection. It makes fair comparisons even more difficult.

An early assessment could highlight where life cycle information is particularly needed and encourage the specification of products whose manufacturers offer that information – thereby improving the accuracy of whole life carbon assessments while also helping to meet targets like those set by LETI and RIBA.

About the author 

Darren Evans - Business leader connecting with people to treat people and planet as the precious resources they are so that we can build a better future together  https://darren-evans.co.uk/ 

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