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2020 / 2021 Edition

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Net zero: why we need to look at whole-life truths

First published in the September 2021 issue of Quarry Management

By Dr Martyn Kenny, sustainability director, Tarmac

The carbon debate is often too focused on embodied carbon measurements that incorporate only carbon emitted during the production of materials and the construction process itself, but there is a more holistic alternative that is critical to achieving net zero and moving towards a circular economy.

Whole-life carbon analysis measures anticipated impacts over the lifetime of a building or infrastructure asset. It considers not only the extraction of raw materials, the manufacture of construction products, product miles and the construction process, but also takes account of emissions during the operation or use of the asset. Plus, it evaluates how the material is selected, how the asset’s design can influence these emissions and what happens at the end of life.

Is our industry considering the whole-life carbon impact of assets to inform material specification? Tarmac’s latest research, ‘Clean construction: unlocking net zero’ confirmed that there is a good level of awareness about the importance of taking a whole-life approach, but that this is not always translating into the adoption of this approach.

Over 70% of respondents confirmed that they understand whole-life measurement principles, but it was just over a third of companies that reported that they are applying this approach in practice.

Why is this a missed opportunity? Because, using embodied carbon measurements fails to consider performance over an asset’s lifecycle, risking sub-optimal design and specification. It does not give enough consideration to aspects such as longevity, resilience or the need for maintenance and repair.

Importantly, it also does not assess how the design, and the materials themselves, can reduce carbon emissions during use or the impacts on carbon at end of life, or how the building or asset can be designed to be repurposed, deconstructed or demolished, and components can be reused, recovered, recycled or disposed.

These lifecycle stages are critical to determining the overall carbon performance and are integral to making the best design decisions and material choices. The transition to a net-zero society requires a greater understanding of long-term performance.

Regulatory change to encourage whole-life analysis is taking place. The recently launched London Plan 2021 includes Policy SI 2 that now enshrines a requirement for developers of schemes referable to the mayor to submit a whole lifecycle carbon assessment and demonstrate actions to reduce emissions.

While there are no mandatory whole-life carbon targets in the London Plan, the guidance includes carbon benchmarks for four building types – offices, retail, education and apartments/hotels. Developers will need to meet these benchmarks.

London’s leadership on this issue is a major step forward, because on many occasions those building an asset may have less interest in its long-term carbon and cost performance and adopt more simplistic embodied carbon evaluation that overlooks whole-life impacts.

Tarmac still receive frequent requests for product carbon data after a project has been completed. It is then too late to consider whole-life performance or influence the design. London’s new policy will change this in the capital by encouraging whole-life thinking upfront at the design stage.

Tackling carbon requires an industry-wide approach and early supply chain engagement to shape and embed whole life into designs from the outset. It is time the industry follows London’s lead and breaks down barriers that exist in the importance placed upon whole-life analysis.

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