The project forms part of a long-term partnership between Star Refrigeration and DHL, who operate the 192,000 m3 J D Wetherspoon distribution hub. Faced with rising maintenance costs and an ageing refrigeration plant originally installed in 2004, DHL sought a future-proof, environmentally responsible solution capable of supporting both firms’ net zero goals. Star's technical and financial analysis showed the existing pumped-circulation ammonia system's limitations and highlighted the efficiency, safety, and life-cycle benefits of upgrading to a modern, low-charge ammonia design.
The business case was compelling. Forecasts suggested that maintaining the old plant would incur approximately £400,000 in upgrade costs between 2024 and 2027, with a further £180,000 expected in running costs. By contrast, the Azanefreezer 2.0 offered a system with no water usage or associated treatment requirements, advanced intelligent controls, and a significantly lower ammonia charge of just 220kg, improving both safety and environmental performance.
The new 290kW system was designed to operate alongside an existing 120 kW Azanefreezer 1.0 installed in 2016. Together, the units provide a reliable, energy-efficient refrigeration solution that supports the facility’s 31,000m3 frozen store. To minimise disruption to operations, Star implemented a phased decommissioning of the old plant during winter, allowing the freezer to remain fully operational throughout the installation.
Since the upgrade, the site has achieved a remarkable 17% improvement beyond the UK’s ‘Best Practice’ benchmark for cold storage facilities of a comparable size. With annual energy savings more than triple the original £5,000-per-month estimate, the project has delivered a payback period of under two years – far faster than projected.
Daniel Johnson, Engineering Manager at DHL, said, “We have analysed the electricity figures before and after the installation, and the results speak for themselves: the new system is saving on average around 617,000 kWh per year. This has produced substantial energy cost reductions and helped us exceed industry efficiency standards. Working with Star Refrigeration has been a very positive experience. Their team took the time to understand our operational demands and sustainability goals, and the new system now provides long-term resilience, efficiency and environmental benefits.”
The refrigeration performance and operational visibility of the site have been further strengthened by Star’s Ethos technology, an AI-driven digital optimisation system that provides real-time monitoring, performance benchmarking, and predictive analytics. Ethos enables Star’s engineering and maintenance teams to identify inefficiencies, anticipate future requirements, and support ongoing energy reductions. Remote monitoring, combined with the expertise of Star’s 30-strong Derby-based team, ensures the system continues to operate at peak performance.
This project is a key milestone in the UK cold chain, as operators face increasing pressure to reduce energy use, lower carbon impact, and comply with future environmental regulations.
Aiden Perks, Regional Sales Manager (Midlands) at Star Refrigeration, said, “This project shows what is possible when businesses commit to forward-thinking engineering and data-driven decision-making. The impact at Daventry reduced energy use, lower costs, and demonstrated the value of strong partnerships that place innovation, life cycle costs, and sustainability at their core.”
With more than 18 months of operational data showing consistently strong performance, the Daventry facility is now one of the most energy-efficient cold stores in the country, demonstrating how industrial refrigeration can support commercial competitiveness and environmental responsibility.
The full project video can be viewed on Star Refrigeration’s YouTube channel at DHL / J D Wetherspoon Daventry case study video (https://youtu.be/BH2stB5Szvs?si=nKO-KwYt4v8LxaZy)