Low Carbon Materials brings carbon-negative ACLA® to its most beautiful project yet at the Chelsea Flower Show in a world's first concrete mix
London, 20 May 2026 — Low Carbon Materials' ACLA® biochar-mineral aggregate features in a net zero concrete mix at this year's RHS Chelsea Flower Show, used throughout the Silver medal-winning Asthma + Lung UK Breathing Space Garden.
The concrete, developed by Getjar with Tarmac, combines oyster shells, ACLA®, and calcined clay. Tarmac precast the slabs, benches and canopy structure at its Cambridge plant before installation at the show. After Chelsea, the garden will move to its permanent home at Breathing Space in Rotherham, where it will support lung rehabilitation and patient wellbeing.
The garden's central platform was engineered by AKT Structural Engineers using the net zero concrete. The mix is a world-first and a potential game-changer for the landscape and construction industries.
About ACLA®
ACLA® is a carbon-negative biochar-mineral aggregate that permanently locks carbon into construction materials. Low Carbon Materials is the UK's biggest user of biochar in construction.
To date, ACLA® has mainly been used to decarbonise asphalt across the UK. It is now being rolled out into concrete, a market that dwarfs asphalt and is in urgent need of solutions to reach net zero. ACLA® can fully decarbonise concrete, enabling net zero mixes. ACLA® has featured in over 40 projects across the UK, and the Breathing Space Garden is the most beautiful to date.
The garden was designed by Angus Thompson Design and built by Dan Flynn.
Photo by Rebekah Kennington