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The challenge of embodied carbon on construction sites

10 Dec 2021

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2021 was the year we came out of the pandemic and seriously took stock of our carbon footprint at home, at work, when we travel, and what our Government’s are doing about the bigger picture.

And while your typical eco-conscious shopper is now swapping avocados for UK apples, we’re seeing that construction companies are doing the same… but looking at the origins of concrete rather than cucumbers.

The technical term here is ‘embodied carbon’. It’s a measurement of the environmental impact of a product for its entire life cycle.

An avocado has much higher embodied carbon than an apple from Hereford because it needs more water to grow, requires more energy for harvesting and packing, and is then shipped half way around the world to arrive at the supermarket.

You can follow the same process for building materials. 100 tonnes of timber from an area that looks like the Amazon (but the paperwork says it definitely isn’t) will have a much higher carbon footprint than a more sustainable timber product sourced in Europe.

The issue we have currently, and this applies to both concrete and cucumbers, is that the UK doesn’t have any legally binding targets on embodied carbon.

When a developer builds a house, Building Regulations set an emissions target for while the dwelling is being occupied. But the environmental impact of the materials used in the construction, and the carbon footprint of recycling the materials when the house is knocked down are completely ignored.

Yet recent research has discovered you can live in a house for 80 years, and the CO2 released will still be lower than the amount created before you moved in.

This is because cement and steel have very high embodied carbon ratings.

So, as a housebuilder, what can you do?

In the last year we’ve noticed how more construction companies are being publicly vocal about their environmental responsibilities and one common commitment is to reduce the embodied carbon of the homes they’re building.

You can’t work on reducing a number if you don’t know what the base number is, so the first step is to look at current construction materials and techniques, and calculate the embodied carbon as it stands today.

Measuring the life cycle of buildings isn’t a mainstream assessment. Until now, it’s only been requested by developers who want to earn additional BREEAM credits, and more recently on large London schemes where the Greater London Authority has insisted lifecycle is checked as part of the planning conditions.

The calculation is very detailed. Every material used on site from the pavement slabs to the skirting board in the spare bedroom needs to be considered. Developers can reduce their embodied carbon if they can prove the materials have been sourced locally or from more sustainable methods, otherwise the calculator uses assumed data.

When the initial legwork is complete, housebuilders can then use the results to work out which products they need to change to have the biggest impact on their embodied carbon scores on future developments.

It’s inevitable that some form of life cycle check will be introduced to Building Regulations, with countries like Denmark and France already introducing such targets, but we’re not at that stage in the UK yet.

Developers who are acting now to measure their embodied carbon will have a head start when such targets become a mandatory requirement for the construction industry.

For more information about life cycle assessments and circular economy reports, contact the Energist Technical Team.

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Author

Jon Ponting

Energy & Sustainability Specialist

Email

Jon Ponting

Energy & Sustainability Specialist

jonp@energistuk.co.uk