Abbey Design Associates (ADA) develops a bespoke water-cooled transcritical CO₂ solution that overcomes elevated water-supply temperatures at a premium M&S underground location in London’s financial district. The innovative design enabled the store to remain on a standardised, low-carbon refrigeration platform despite the site’s challenging conditions.

Abbey Design Associates is proud to announce it has been shortlisted for Retail Project of the Year at the RAC Cooling Awards, recognising a full refrigeration refit of an M&S Food store at One New Change in London. The project replaced a water-cooled HFC system with an innovative transcritical CO₂ solution engineered to run in conditions long regarded as an edge case for natural refrigerants.

The c.9,000 sq. ft inner-city store presented a rare combination of constraints. The landlord’s shared water circuit ran at temperatures of up to 44°C, pushing the system’s gas cooler outlet toward 46°C, a regime that conventional transcritical CO₂ systems are highly sensitive to. The underground location added to the difficulty, with all cabinets and plant equipment delivered through goods lifts and an underground loading bay under strict size limits. Adding further complexity, the entire project had to be designed, delivered and commissioned within a six-month programme between September 2025 and March 2026.

Rather than fall back on higher-emission alternatives, such as retaining high-GWP synthetic refrigerants, using a secondary glycol system, or installing integral air-cooled cabinets, each of which would have increased Scope 1 and Scope 2 emissions, ADA developed a bespoke engineering solution that held the line on a natural refrigerant. The team increased the gas cooler size to reduce the temperature difference and optimise compressor selection, and added an auxiliary gas cooler, a plate heat exchanger fitted after the main gas cooler with a bypass, that draws on the domestic cold-water supply for additional cooling whenever the gas cooler outlet exceeds 40°C. This kept compressor displacement, power consumption and water use to practical levels.

To manage the resulting flash gas, ADA also agreed a deviation from M&S’s standard specification to incorporate parallel compression, believed to be among M&S’s first parallel-compression transcritical CO₂ installations.

The result is a refit aligned to M&S’s Plan A standards that concentrates the engineering complexity in one part of the system, while leaving the wider store refrigeration infrastructure standardised, scalable and operationally efficient. With CO₂’s negligible global warming potential, the system is positioned for the lowest total environmental warming impact as the UK grid decarbonises, while minimising embodied carbon and eliminating the Scope 3 emissions associated with synthetic refrigerant production. It is also fully energy-monitored and data-logged, giving M&S visibility of performance over the years ahead.

Abbey Design Associates believes the design offers a workable, deployable and scalable blueprint for inner-city stores in shared premises, turning the one-of-a-kind site into a repeatable, low-carbon standard.

Commenting on the project, Conor Eaton-Smith, Technical Projects Director at Abbey Design Associates, said:

“One New Change was exactly the kind of store the industry tends to call impossible for CO₂. By developing a new solution we kept M&S on a single, sustainable refrigeration platform, and showed that high-ambient, space-constrained sites no longer need a bespoke, high-emission system of their own.”

Commenting on the award shortlist, Chris Chisman, Managing Director at Abbey Design Associates, said:

“Being shortlisted for Retail Project of the Year is fantastic recognition for our team and the collaborative approach we’ve built with M&S. This project demonstrates that some of the industry’s most technically challenging retail environments no longer have to compromise on their sustainability ambitions. By combining engineering expertise with a willingness to challenge conventional approaches, we’ve shown that natural refrigerants can be deployed in applications that were once considered beyond reach.”

About Abbey Design Associates

Abbey Design Associates (ADA) are a renowned refrigeration consultancy firm who specialise in the design and project management of complex commercial and industrial refrigeration systems.

Combining engineering expertise with practical industry experience, ADA develops innovative solutions for some of the industry’s most challenging refrigeration applications, helping organisations transition to sustainable technologies whilst optimising operational performance, regulatory compliance and long-term sustainability.