Why the Chilled Aisle Is Failing in UK Heat

As the United Kingdom experiences hotter summers, the performance of chilled and frozen aisles in grocery retail is coming under intense scrutiny. The issue is rarely just about the age of the equipment, as Epta suggests. High ambient temperatures do not simply create a bad day for refrigeration systems; the explanation is usually much more complex, rooted in the way an individual system was designed, where it is located, and how it has been serviced and maintained over time.

Every refrigeration system is specified around the predicted conditions it is expected to handle over a 15–20-year period. In practice, that includes the local climate, likely summer peaks, building layout and the cooling load inside the store. The issue now is that those original assumptions are outdated, and the conditions some stores are experiencing are starting to exceed the tolerance the system was designed around. Those assumptions may have been perfectly reasonable when the equipment was installed. The difficulty now is that UK stores are facing warmer summers and longer periods of heat than many older systems were originally planned around. In other words, the operating window is moving at pace, and some systems are being challenged to perform in conditions that sit beyond their original design.

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This summer’s heatwaves have pushed UK supermarket refrigeration into the spotlight, and as a result shoppers usually see the problem first at the shelf edge, through empty cabinets or temporary notices explaining equipment faults. By that point, the issue has already moved beyond the refrigeration system itself and into the customer experience. For supermarkets, the challenge is therefore better understood as an estate planning issue than a seasonal inconvenience.

That makes the public debate around ageing supermarket fridges useful only up to a point. Age can increase exposure, especially where equipment has carried years of wear or where investment has naturally followed wider asset refresh cycles. However, age on its own does not tell the full story. With the right maintenance history and sensible upgrades, an older system can still perform well, even a newer installation can become vulnerable if it was designed with too little margin or has not been maintained properly. The better indicator is the condition of the system when the heat arrives. During milder weather, small weaknesses can be managed inside the normal operating range. For example, external heat rejection equipment that is already underperforming may not necessarily create a major incident in cooler conditions. However, under sustained heat, the same weakness can quickly become unmanageable and visible in store.

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Heatwave readiness needs to start before the forecast changes. In many cases, improvement does not require a full system replacement. At one site, shading external equipment from direct sunlight may reduce solar gain whilst maintaining ventilation for the system. Adiabatic support may be appropriate in another setting, and display case doors can help lower the load on the refrigeration system, while better coordination between air conditioning and refrigeration can make the store environment easier to manage during warmer periods. Although these changes may not attract headlines, they can influence how much strain the system has to cope with.

Technology and digitisation

Alongside maintenance, digitisation is playing a bigger role in helping refrigeration estates prepare for prolonged heat. Continuous performance monitoring and predictive maintenance tools allow retailers to identify early signs of underperformance before they become critical failures. Platforms such as MyEpta provide a single digital gateway to equipment data, documentation and service information, helping retailers gain clearer visibility across their refrigeration assets. Within this ecosystem, GAM supports the centralised monitoring of anomalies, enabling service teams to detect issues earlier, prioritise interventions and reduce the risk of disruption when systems are under maximum pressure.

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Extreme temperature efficiency

There is also a design lesson. Refrigeration systems have to balance capacity with normal operating efficiency. Designing too close to the expected load leaves less room when conditions change. Designing for rare peaks alone can leave a store carrying unnecessary redundancy for much of the cooler periods of the year, which can lead to its own problems. Modern refrigeration therefore has to manage that balance with better site data, system architectures and technology that take future weather into account. Epta has also developed ETE solution, or Extreme Temperature Efficiency, as part of that conversation. The technology was developed to support CO₂ refrigeration in naturally high ambient environments, allowing the system to operate in these demanding conditions.

The concept is relatively simple. Under high ambient conditions, CO₂ systems produce more flash gas, which reduces the amount of useful liquid available to cool and ultimately add cooling capacity. ETE is designed to sub cool the refrigerant to reduce the amount of flash gas being created, so it can continue operating effectively when outdoor temperatures rise. The technology was originally developed for markets with high temperature environments, including Southern Europe, the Middle East and Australia. As a result, ETE is now being explored in the UK as retailers look more closely at how CO₂ systems perform in warmer operating conditions. It is being trialled with a major UK supermarket, while installations in hotter climates are giving Epta further insight into how the approach performs under sustained high-temperature conditions.