Concrete: let’s separate the carbon facts from the fiction

As we collectively begin to map our recovery from the Covid-19 crisis, the ways the UK will achieve the target of net-zero carbon by 2050 is coming into sharper focus. 

The UK built environment sector’s aspirations to ‘Build Back Better’ are rightly centred on delivering positive social, environmental, and economic outcomes. But it’s critical that decisions are based on clear facts, accurate data and shared action. 

As much as construction needs to avoid a carbon rebound in the short term, it’s equally vital that we plot a clear course now for the longer journey – to achieve a meaningful net zero. Those that design our buildings and infrastructure, as well as the people that shape our legislation, must therefore have their actions informed by data and evidence rather than purely by rhetoric.

It’s no secret that in some quarters there are currently widely held misperceptions and negativity around the use of concrete. In reality, concrete often remains the right choice of material due to numerous critical performance benefits including its sustainability, passive cooling potential, and flood and fire resistance.

The facts are important. Global figures are often quoted, almost always missing the fact that 95 per cent of the concrete used in the UK is manufactured here, using locally and responsibly sourced materials. The UK concrete and cement industry has a strong track record. It has been measuring and reporting on various sustainability metrics for over a decade now, already having delivered a 53 per cent reduction in absolute carbon dioxide emissions since 1990 – meaning it is decarbonising faster than the UK economy as a whole. 

This clearly isn’t the end of the journey. The UK concrete and cement industry is fully committed to delivering net zero, reducing emissions from production and supporting the Government’s target. 

Critically, it plans to do this without offsetting emissions or offshoring production facilities – believing that net zero should be achieved by reducing emissions from the construction materials manufactured in the UK, rather than by simply replacing these with imports and moving the problem abroad. The aim should be to retain jobs and economic value in the UK whilst ensuring that the UK takes responsibility for the emissions it creates.

This collective early action by industry means it is already possible to construct buildings and homes with a lower environmental impact across their long lifetimes by using contemporary low carbon concrete.

However, the truth is that many projects are currently conceived without adequate consideration and measurement of whole lifecycle carbon impacts. All too often short-term embodied carbon in building material selection takes precedence over the carbon emitted across the full lifecycle of an asset.

Specification decisions and carbon measurement should rather consider the longer-term operational performance of a building or structure, together with its flexibility to adapt to its users’ needs and recyclability at the end of life – as well as the materials used to construct it.

To do this however, it’s essential more, better informed and intelligent conversations are held about material specification, adopting responsibly sourced, sustainable supply chains and an increased focus on Lifecycle Carbon Assessment (LCA).

But while LCA has great potential, it’s clear that more data transparency and robust, consistent standards are needed. Uncertainties, assumptions, and omissions in LCA studies and environmental product declarations (EPDs) suggest that accurate and like-for-like comparisons across building materials are still extremely complex. 

Currently, these studies are not facts but interpretations – with multiple variables and estimated calculations – and so should be treated as such. Urgent attention needs to be given to developing robust LCA techniques and standards to ensure carbon is assessed evenly and in the most effective way, and not informed by a material bias based on perceptions and should focus assessment at a building level.

It’s equally important that material efficiency and building longevity are put at the heart of design so that we build less and invest resources more efficiently. This is an essential part of a future circular economy and key to unlocking greener, more sustainable assets and infrastructure.

This is particularly key as society continues to adapt to climate change, where we need to ensure our buildings help to look after us, save energy and are appropriately designed to cope with future weather conditions. By building with concrete we can take advantage of its potential to reduce maintenance needs and greatly enhance energy efficiency through its use of thermal mass. 

Now more than ever, we need to be applying measures to help ensure long term resilience to overheating as a result of climate change. Of all the adaptation measures, a building’s fabric, along with its form and orientation, are the most fundamental to get right.

When it comes to end of life, there are no unknowns with concrete. It is 100 per cent recyclable and can be crushed for reuse as a cost-effective material for hard core or used as a recycled aggregate in new concrete. Despite construction waste often being framed in terms of ‘tonnes of concrete’, in truth all is reused and almost none ever goes to landfill. Moreover, 90 per cent of hard construction and demolition waste is recycled as aggregates.

Looking forward, R&D teams are working to deliver a wave of innovative new concrete solutions. Already, high-performance concretes that are lightweight, ultra-thin and thermally insulating are helping architects and engineers to shape a safe, exciting and sustainable built environment that uses less primary finite resources. Pollution eating, self-healing, water permeable and bioreceptive concretes are just some of the wave of new materials being developed that in time will further contribute to lowering emissions, and a greener urban environment.

Together, all of this work can drive decarbonisation. It should also help to drive more informed and intelligent conversations about the materials we use across the built environment. 

In the journey to net zero we must put aside some of our historical perceptions and focus on the facts and data of today and the potential for tomorrow. In this way, we can all be sure we are making the right decisions in the pursuit of net zero and beyond.

Elaine Toogood is Head of Architecture at MPA The Concrete Centre