The Building Industry Needs to Take Embodied Carbon Seriously, Says New Report

Embodied carbon is the carbon emitted during the manufacturing of building materials and the construction process. It's a confusing name, because the carbon is not embodied in the building, but is in the atmosphere already, which is why some call it "upfront carbon emissions." Embodied carbon is rarely regulated and most of the building industry ignores it.

Now, a new report—"Net Zero Buildings–Where Do We Start?"—prepared by professional services firm Arup for the World Business Council for Sustainable Development (WBCSD) estimates that only 1% of buildings even get assessed for their whole-life carbon footprint. And really, why should they bother? Nobody is asking for it.

Besides, as Eric Cory Freed cleverly notes, architects' eyes have been elsewhere. For 50 years the industry and the regulators have been concerned about energy efficiency. It's only since the Paris Accord of 2015 that we have had hard targets for reducing carbon emissions, requiring they be cut in about half by 2030 and get to net zero by 2050. And if you look at modern, relatively energy-efficient buildings, one finds that as much as 50% of their whole-life emissions come from embodied carbon, not operating emissions. But almost nobody looks.

Chris Carroll of Arup, one of the authors of the report, says this has to change. Carroll notes:

“We have to consider carbon like we currently consider money. The idea that you would build a project and not know how much it costs financially would seem incredible. But the industry currently doesn’t know where it stands when it comes to carbon emissions, making it difficult to set meaningful targets and drive progress."

Roland Hunziker of the WBCSD concurs:

“To get the construction industry on track to reach global climate targets, all companies need to start measuring the full carbon footprint of their real estate assets."

The report studied six modern buildings, doing a Whole Life Cycle Analysis (WLCA) of each. It wasn't easy or fast: data on materials were inconsistent and opaque. So with less than nine years to cut emissions in half, the report has to start at the very beginning, with a call to:

• Measure everything, at all stages, on all projects.
• Develop a consistent methodology and approach.
• All components, systems, and materials to have a carbon intensity certification.
• A better understanding of supply chain and national energy grid decarbonization trajectories. [a building material made in a country with coal-fired electricity might have a completely different footprint than one made in another country.]
• Clear, simple targets.
• A clear and precise definition of net zero buildings aligned with overall global decarbonization, emerging net zero definition, and the Paris Agreement.

One of the six buildings was a mass timber residential structure; the others were conventional construction, where steel dominated the upfront carbon emissions, with concrete in second place. Treehugger recently reported how half of steel production went into buildings and that it was responsible for 11% of all emissions.

The report states "the decarbonization of the built environment is integral towards the attainment of the IPCC1.5°C scenario." It calls for operational carbon to be net zero by 2030 and embodied carbon reduced by 40%, with buildings being completely net zero by 2050. However, the authors note that "there is also a lack of global consensus on methodological assumptions and definitions of net zero proportionate to required GHG emissions reductions, removals, offsetting and established explicit targets."

The whole thing is a muddle and a mess. But they do conclude:

"The building industry must now come together and commit to measuring the whole life carbon emissions associated with all future projects in a clear and transparent way demonstrated here. If we start to systematically collect and use this information at the beginning of each project, then we can achieve an immediate cut in the 14 gigatonnes of carbon this industry is responsible for globally each year. By setting clear targets as discussed in this report we can halve both the embodied and operational carbon in buildings. The numbers in this report show that this goal can be within our reach. This would in turn make it possible to halve our emissions in the next decade, an act that will genuinely put us on track towards a net zero built environment."

Could the building industry halve its emissions in the next decade? Only if everyone acknowledges the importance of embodied carbon and agrees on what net zero really means. Only if everyone puts down their pencils right now and started rethinking everything that is being designed or planned right now, buildings take a long time. Only if every official plan in every jurisdiction was changed tomorrow. Only if building codes were redrafted overnight. Only if the entire development industry was reinvented.

It certainly sounds like a challenge.