The Facts
Client – Tesco
Location – Harlesden Superstore
Project Type – Energy Innovation Trial
Objective – Trial the first Danfoss CO₂ Heat Recovery Unit (HRU) in the UK retail sector.
Duration – 2 weeks
Completion Date – 21/02/2025
Budget Cost – £91,291.72
Technology Provider – Danfoss
The Challenge
Tesco continues to lead the charge in store decarbonisation and electrification. At Harlesden Superstore, the goal was to harness waste heat from the refrigeration system to reduce reliance on supplementary heating and drive down operational carbon emissions.
Once the heat has been captured in the HRU, it is sent to the AHU LTHW coil to then distribute tempered air to the sales floor. The challenge was to design and trial a compact, self-contained heat recovery solution that could seamlessly interface with the existing refrigeration and heating infrastructure while supporting the development of a more efficient and dependable low carbon heating system.
We needed to maintain the store temperature whilst we undertook the installation to allow business as usual operation, which we achieved through the careful design of a temporary bypass arrangement that ensured uninterrupted heating and supported the overall aim of delivering a sustainable heating solution.
To ensure he project aligned with wider energy objectives, the team also evaluated how the trial could contribute to Tesco’s long term plans for refrigeration heat recovery across its estate.
The Solution
Danfoss CO₂ Heat Recovery Unit (HRU)
- Reclaiming Waste Heat
- Captures waste heat from the store’s CO₂ refrigeration system via a plate heat exchanger, supporting a more efficient low carbon heating system.
- Heat stored in the Danfoss HRU 1,000-litre thermal buffer tank, providing stable heating during refrigeration cycling and part-load conditions.
- Smart, Self-Regulating System
- Integrated controls manage temperature, flow rates, and include built-in heat metering.
- Communicates directly with refrigeration system, to streamline the heat recovery unit installation with minimal integration complexity
- Capable of remote access and integration with existing BEMS for fault and operational monitoring.
- Ease of Installation and Maintenance
- Maximised opportunity by using modern methods of construction and having the unit manufactured off site to minimise installation time.
- Pump and valve layout customised to Tesco’s maintenance access requirements.
- Compact, robust design ideal for constrained store environments.
- Performance Snapshot (First 6 Days)
- Heat stored at ~58°C, with supply flow averaging 49°C
- Return air from shop floor: 20°C
- Recovered and supplied 5,697 kWh to the store’s heating system in just six days, demonstrating the potential for refrigeration heat recovery at scale.
- Significantly reduced the run time of supplementary heating.
- Contingency
- New electrical boiler installed with inbuilt safety features and a full control matrix.
- Ensures efficient boiler backup without unnecessary operation
The Result
- First successful retail trial of the Danfoss HRU in the UK
- 5,697 kWh of low-carbon heat delivered in under a week
- Seamless integration with refrigeration system and progress towards a store wide low carbon heating system
- Lower running costs and reduced electric heating consumption
- Reduced carbon footprint from better thermal energy utilisation
- Demonstrated scalability across various store formats
Innovation in Action
This trial shows how forward-thinking engineering can transform refrigeration waste heat into a valuable energy source supporting a more efficient and scalable low carbon hearing system that cuts costs and reduces store emissions.
If we proposed to use a conventional gas boiler, it would have consumed over 45 tonnes of carbon per year, compared to the projected 250,000 kWh per annum that can be delivered through effective refrigeration heat recovery.
The results highlight how the Danfoss HRU trial has the potential to become a repeatable sustainable heating solution across a wide range of store formats.