Holcim UK and Canary Wharf Group achieved net zero concrete with a projected -14 kgCO₂e/m³ footprint, combining fossil emissions and biogenic carbon storage
Biochar derived from waste coffee grounds and wood enabled up to 80 percent emissions reduction versus traditional CEM I concrete
Large-scale trials in London signal a viable pathway for decarbonising one of the world’s most emissions-intensive industries
A consortium led by Holcim UK and Canary Wharf Group has delivered what it describes as an industry first: net zero concrete validated through full-scale construction trials in one of Europe’s most prominent commercial developments.
The six month research and development programme tested ultra low-carbon concrete mixes across multiple live projects at Canary Wharf, targeting one of the most difficult sectors to decarbonise. Concrete production accounts for roughly 7 to 8 percent of global CO₂ emissions, placing it at the center of both regulatory scrutiny and investor focus.
The collaboration brought together contractors O’Halloran O’Brien and engineering consultancies including Arup, Ramboll, B&GE, Thornton Tomasetti, Walsh Associates, and Robert Bird Group, alongside academic partners from Queen’s University Belfast and the University of Cambridge. The objective was clear: demonstrate that next-generation materials can match or outperform conventional concrete while sharply reducing emissions.
Biochar and Circular Materials Deliver Negative Emissions
At the core of the breakthrough is a biochar-based mix incorporating waste streams from Canary Wharf itself. Coffee grounds collected from local retailers and coppiced wood were converted into biochar and integrated into the concrete.
Initial testing showed an 80 percent reduction in net Global Warming Potential compared to traditional Portland cement mixes, achieving 69 kgCO₂e/m³. Further optimisation pushed performance into negative territory, with a projected net GWP of -14 kgCO₂e/m³.
The mechanism is straightforward but powerful. Carbon absorbed by plants during growth is captured in the biochar and permanently embedded in the concrete, turning buildings into long-term carbon storage assets.
Jasen Gauld, National Readymix Product Development Director for Holcim UK, said: “The aim of these trials was to show that next-generation concrete mixes can perform as well as, or better than, standard concretes – giving contractors and the wider supply chain confidence to adopt them and embedding circular thinking into the buildings we help create. “By optimising the biochar-coffee mix, we have achieved net zero concrete – a Holcim first – while maintaining strength, durability, and circularity. Where increased binder might otherwise have been needed, our products can remove that requirement, reducing overall embodied carbon. At the same time, the carbon in the biochar is locked into the concrete, allowing buildings to fulfill a new role as long-term carbon stores, keeping CO₂ safely out of the atmosphere. This demonstrates that high-performance, low-carbon, circular materials are ready for real-world use.”
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Scaling Validation Through Live Construction Projects
Unlike laboratory demonstrations, the materials were tested under real construction conditions. Trial pours began in April 2025 with a full-scale slab beneath a new theatre at Wood Wharf, followed by two-metre-deep raft slabs at the Bank Street site in September.
Earlier applications included underwater counterweights for the 10-metre “Whale on the Wharf” public art installation, offering a visible proof point for circular construction in practice.
In parallel, alternative mixes using graphene achieved more than 50 percent emissions reductions while improving strength and durability, potentially lowering total material requirements. A further mix incorporating ECOCEM ACT provided additional benchmarking against conventional CEM I concrete.
All materials will now undergo two years of monitoring by project partners including Skanska, Arup, and Queen’s University Belfast to generate verified performance data. This step is critical for regulatory acceptance and large scale adoption, particularly as building standards tighten across Europe and globally.
Real Estate Developers Drive Market Adoption
For Canary Wharf Group, the initiative reflects a broader shift in the role of developers as both clients and validators of emerging technologies.
Jonathan Ly, Director of Structures at CWG, said: “This collaboration represents a pivotal moment for the real estate sector’s transition to net zero. As both developer and main contractor, CWG occupies a unique position in the industry where we can validate next-generation materials on live projects at pace, allowing us to build the market confidence that low-carbon concrete needs to become mainstream. “Achieving net-zero concrete with our biochar-coffee mix demonstrates that circular economy principles aren’t just aspirational, they can deliver measurable environmental and commercial value. By transforming spent coffee grounds from our own retailers into a construction material that sequesters carbon, we’re proving that sustainable development can be both ambitious and practical.”
What This Means for Industry and Investors
For executives and investors, the implications extend beyond a single project. Cement and concrete are central to infrastructure pipelines worldwide, and decarbonisation pathways remain limited. Technologies that combine emissions reduction with carbon removal potential could reshape procurement strategies, carbon accounting, and asset valuation.
The integration of waste-derived materials also aligns with tightening circular economy regulations in Europe and emerging disclosure requirements tied to embodied carbon.
If performance data confirms durability and scalability, net zero concrete could move rapidly from pilot to procurement standard. That would mark a significant shift in how the built environment contributes to climate targets, transforming buildings from emissions sources into carbon sinks.
The Canary Wharf trials offer a glimpse of that transition already underway, with implications that reach far beyond London’s skyline.
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