An opinion piece by Mike Cook, Visiting Professor, Imperial College and Chairman, Seratech Ltd

Guilt-free Concrete?

Construction Materials must change

We can no longer be in any doubt that global warming and climate change is a huge and growing challenge to humanity (Ref. 1 World on brink of five ‘disastrous’ tipping points – The Guardian) and that much of the problem has been caused by the use of fossil fuels in our built environment. Yet it is taking longer for us to recognise that a sizeable part of this problem is in the materials we use to construct our built environment – the up-front, embodied carbon. Embodied carbon of construction is currently responsible for around 14% of global CO₂ emissions. In the developed world we are starting to argue for retaining and reusing existing buildings – something to be encouraged. But this will never be enough to reverse the trend – over the next 40 years global construction is expected to match the total construction to date.

Why do we need new Construction?

Firstly, in less developed nations they do not have the basic buildings and infrastructure needed to provide adequate public health and resilient homes, schools, hospitals. As these communities develop so will the demand for new construction grow if we are to deliver a “safe and just space for humanity”. (Ref. 2 Doughnut Economics – Kate Raworth)

Secondly, in the well developed nations, climate change is leading to rising sea levels, more severe and frequent extreme weather, drought, and floods. The response will be to build defences against these threats and to create new, and more resilient, infrastructure. At the same time, we will need new infrastructure to generate zero-carbon energy (whether wind, wave, nuclear, solar, hydrogen or others). All this construction will come with a high level of CO₂ emissions, contributing to the greenhouse effect and climate change.

We need construction but have to find ways to make construction materials that do not contribute to climate change. The zone spoken of by Kate Raworth in Doughnut Economics, where we neither overstep the ecological boundaries that ensure a habitable planet nor underdeliver on the physical/social needs of humanity, turns out to be extremely narrow. In fact, I believe there can be no “safe and just space for humanity” unless we can build effectively with zero embodied carbon now.

Where is the light at the end of the tunnel?

Most construction firms and materials suppliers have mapped out ways to achieve net zero, but these hinge on finding effective ways to capture substantial residual carbon emissions from their processes (emissions from cement kilns, from steel blast furnaces or from waste timber burning). The need to decarbonise material production seems to sit with “carbon capture and storage”, but can this be achieved at the scale we need and a cost we can afford?

This challenge has caused me to shift my focus towards construction materials. Since retiring from practice as a partner of Buro Happold, I have been teaching and researching at Imperial College London, and I want to use this opportunity to alert you to a materials development there that I find particularly exciting – www.seratechcement.com.

A couple of PhD students joined up their individual areas of research to discover that rather than try to capture carbon or find yet another way to replace some of the cement with a new SCM (supplementary cementitious material), they could achieve both these in one process.

Seratech offers scalable, affordable carbon capture to any industry with CO₂ in their flue emissions, including cement kilns. The Seratech process captures waste CO₂ emissions directly from flue gases, through a series of simple and economical chemical reactions that can be applied to any industrial emissions directly. The patent-pending process produces two valuable materials for use in construction: a silica material that can be used to replace a proportion of the cement in concrete – reducing its carbon footprint, and magnesium carbonate that can be used to make a range of zero carbon construction materials and consumer products. The only feedstock required for the processes is olivine, which is an abundant mineral readily available from quarries around the world.

That’s the idea in a nutshell – Seratech can provide the capacity for a range of industries to manage, capture and store their CO₂ emissions, hence living up to their carbon emission targets. You can hear more about this here #13 Net Zero Guilt Free Concrete? (podbean.com), and there is an event, courtesy of AKTII as part of London Design Week on 20^th September where you can see Seratech in action: Crinkle-Crankle Concrete.  

Regarding concrete, the Low Carbon Concrete Routemap, which is the culmination of two years’ work by the Green Construction Board’s Low Carbon Concrete Group, provides a very useful guide to recent and active research (Ref. 3  Low Carbon Concrete Routemap published by The Institution of Civil Engineers (ICE). There are many new ideas and approached being explored, but it has taken many years of research to get to this point and could take many more years of slow incremental development to get it into construction and achieve substantial, global reduction of embodied carbon.

The challenge now is to get the construction industry to not just draw route maps but to roll up its sleeves and invest its time and money in something that is out of their comfort zone. This requires substantial investment and concerted global action from designers, manufacturers, contractors, funders, regulators and developers.

Construction is here to stay – in the global north and south the demand is unstoppable. But if we want there to be a “safe and just place for humanity” fifty years from now, we will only achieve it if construction becomes zero carbon NOW. It is in our hands to effect this transformation.

Guilt-free Concrete?

If and when we are able to build with materials that have zero embodied carbon this will not give us licence to blast concrete across the land. There will still need to be a change of attitude to ensure that everything we build has value and purpose – that it does far more good than harm and allows us to navigate within the doughnut’s defined zone – the “safe and just space for humanity”. For this we will need better rules than we have presently to decide if, what and where we build. We will need to think about our relationship with the natural world. So, using concrete, even if it is zero-carbon, still comes with responsibilities. There is no get out of jail free card.

To build a picture of how we need to change the way we prioritise our construction activities I suggest you look at “Flourish” by Sarah Ichioka and Michael Pawlyn (Ref. 4) and Living Building Challenge for practical guidance (Ref. 5).

References:

(Ref. 1) – The Guardian – World on brink of five ‘disastrous’ tipping points, study finds: 9^th Sept 2022, Article Damian Carrington Environment editor

(Ref. 2) – Doughnut Economics – Seven ways to Think Like a 21^st Century Economist: Kate Raworth. Random House 2017

(Ref. 3) Low Carbon Concrete Routemap published by The Institution of Civil Engineers (ICE)

(Ref. 4) Flourish – Design Paradigms for Our Planetary Emergency; Sarah Ichioka and Michael Pawlyn. Triarchy Press 2021

(Ref. 5) Living Building Challenge: Guidance to Achieve regenerative outcomes through intelligent development.