22 August 2023

Net zero carbon and broader sustainability in construction

Sustainability is a watchword for the construction industry. Projects are keen to state their ‘green’ credentials – sometimes controversially, especially when it comes to definitions like net zero, or the question of whether to retrofit or rebuild. What do people actually mean when they claim a building is sustainable and what is good practice?


Government policy  is using the UN Sustainable Development Goals as a framework, but those seventeen goals are wide-ranging. Sustainability is a diverse and multi-faceted thing but, as Gilles Alvarenga (Thrive Associate, Chetwoods) described, in construction it’s usually all “carbon, carbon, carbon”.

Tata Steel Construction Summit 2023

Operational and embodied carbon

Nevertheless, carbon emissions are the starting point when trying to address the question of whether the construction industry can achieve net zero. Whether the industry is ‘ready’ or not really depends on how the topic is looked at.

Consistent tightening of building regulations over the last few decades means that operational carbon – the emissions associated with the use of the building – is now relatively low. As a whole, the construction sector has been on a journey with operational carbon, to the point that it can now deliver relatively efficient buildings in use.

Understanding around embodied carbon remains low, however. Awareness is increasing, but embodied carbon remains unregulated. A similar journey needs to be taken with embodied carbon, and some steps have been made – such as through LETI and RIBA carbon targets, and the industry’s own Proposed Document Z. However, time pressures mean this new journey needs to be undertaken significantly faster.

Meridian Water is a twenty-year regeneration project in the London Borough of Enfield, creating 10,000 homes and 6,000 jobs next to the Lee Valley Regional Park. It is, in the words of Rafe Bertram (Sustainability Lead, Meridian Water, Enfield Council), “aligned with the forefront of sustainable development worldwide”.

Key to the project was starting with a clear definition of zero carbon. By 2050, nearly 70% of carbon is expected to be from the construction of buildings, because operational emissions have been tackled so well. That means tackling not just operational energy and carbon, but energy during construction, operation and end of life.

The UK Green Building Council’s net zero carbon buildings framework therefore provides the definitions for the project’s net zero scope.

Using design to address carbon emissions

Jonathan Munkley (Technical Director, WSP and Co-founder of ZERO) introduced the ZERO playbook, an interactive knowledge base combining the insight of over one hundred industry professionals and experts. Among the topics covered by the playbook, it asks: ‘why measure embodied carbon?’

“To manage something effectively, it’s important to be able to measure it accurately. The converse is also true: if something is mismeasured, it’s likely to be mismanaged.”

For the construction industry, an uncomfortable truth is likely just around the corner: as embodied carbon starts to be measured more accurately and more often, emissions accounted for are likely to increase at first. But with more accurate measurement comes the ability to lower them with greater confidence, and then real, long-term carbon savings can be realised.

One way to illustrate how everything has a knock-on effect for everything else is looking at how lowering operational carbon can increase embodied carbon. This is because more material – such as insulation – is needed to drive greater operational efficiency.

The reverse of that is when specifiers exclude items like solar panels for the embodied carbon they would add to a project. Such an approach, however, doesn’t necessarily address the impacts created by energy generation elsewhere, or take into account ongoing efforts to decarbonise the national grid.

Sustainability is often thought of as making buildings more expensive, but that is because technology is often used to address shortfalls between intent and real-world performance. Rather than an over-reliance on technology, sustainability can be designed in from the earliest stages of a project. And ‘sustainability’ means just that – a more holistic approach beyond ‘just’ carbon.

Embracing circularity and adaptability

By creating products and components capable of spanning multiple building life cycles, material extraction and use, and emissions associated with manufacturing and disposal, can be drastically reduced or even eliminated entirely.

Gilles Alvarenga encouraged a different perspective on how we view buildings: rather than looking at the building as an asset, what if we viewed it as a collection of components that have future value?

What often limits this approach is the idea that a building designed for one use can’t easily be adapted into a different use. Rafe Bertram offered a unique take on this by observing: “Buildings are kind of similar to each other. They have to fit people into them.”

In other words, adaptable, circular buildings where components can be reused don’t have to be radically different from what we are constructing now.

It comes back to the early design stage thinking: how easy would it be to adapt, say, a school into a residential building or an office building? Considering timescales is important too – is a building expected to be used for twenty years or one hundred and twenty years?

In terms of the industry’s knowledge and understanding, the circular economy is a little way behind – but it is coming and will increasingly be part of construction project requirements. Meridian Water is working to embed circular economy principles by using the Excess Materials Exchange platform. The platform certifies material to ensure it has the highest possible value, then connects projects in the borough who can use that material. 

Delivering net zero

Delivering a net zero project requires a clear vision, and engagement  throughout the supply chain .

The construction industry is at the beginning of a journey towards low embodied carbon, adaptability and circularity. In many ways, however, it has always done some of these things. There is an ecosystem there waiting to be tapped into; all of the tools and thinking are already there. It’s more a question of putting value on ‘new’ ways of delivering projects.

This is where triple bottom-line decision-making comes in. Rather than being put off by upfront financial costs, it’s essential to make decisions where social and environmental factors are taken into account too. Through this, aspirations can be made into a reality that gets people excited.

Rafe Bertram reminded us that: “Industries change, and that’s fine. It’s a cycle of growth and decline. One industry feeds into another; one approach leads to new approaches.” The construction industry is not immune to that cycle, so if supply chains are to engage in these new visions, we must consider how they might need to change.

Showcasing industry’s progress and vision at Construction Summit 2023

While government policy and regulation can prompt change where it might not otherwise have been forthcoming, it can also take a long time to be made. Businesses are often ready to lead when the government won’t legislate far enough.

That is what led to Tata Steel UK and Constructing Excellence coming together to create the Construction Summit, with 2023’s edition being the first. It represented an opportunity for thought leaders and decision-makers to come together to see where supply chains are making progress. Audiences could learn from best-practice examples, and be inspired by one another to continue their own positive journeys.

The Summit featured presentations across three different strands. Each strand was viewed through the lens of productivity, sustainability and future paths, to give a complete snapshot of where the construction industry is today, and what it is working towards in the short, medium and long term.

For audiences who couldn’t attend the Construction Summit, each strand has been written up into an individual white paper capturing all of the topics discussed on the day. Download the white papers using the links below.

•    Supply chain
•    Climate change and net zero
•    People and skills 

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