The challenge of embodied carbon on construction sites

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 Governments 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 currently have any legally binding targets written into building regulations 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 the demolition, recycling and processing of 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 couple of years 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.

Although awareness is growing rapidly, measuring the life cycle of a building still isn’t a mainstream assessment. Until recently, 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 requires the measurement of carbon as part of the planning conditions.

The calculation of embodied carbon 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 building elements they need to turn their attention to, to have the biggest impact on reducing their embodied carbon across current and future schemes.

So, what’s the closest thing we have to regulation in the UK?  

Although not a legal building regulation, a number of Local Authorities (such as Bristol and London) state the requirement to measure the embodied carbon of applicable projects during the planning process. In addition, there are a number of voluntary schemes which developers can opt into to measure and reduce embodied carbon such as UK Green Building Council (UKGBC) Net Zero, BREEAM, comparison against Low Energy Transformation Initiative (LETI) / Royal Institute of British Architects (RIBA) benchmarks, or the recently released Net Zero Carbon Building Standard (NZCBS) pilot.

The NZCBS pilot is the most comprehensive benchmarking and standard setting methodology to date, and is pegged to inform the illusive and (hopefully) impending Part Z of the Building Regulations that will govern embodied carbon targets.

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, get in touch today.