Planning for Heatwaves in Supermarket Refrigeration – A Resilience Framework for CO₂ Systems

Key words: CO₂ refrigeration systems, supermarket refrigeration, heatwave resilience

Introduction

The summer of 2024 marked yet another alarming milestone in the global climate crisis, tying with 2023 as the hottest on record (https://climate.copernicus.eu/surface-air-temperature-august-2024).This trend is not an anomaly but part of a persistent and intensifying pattern of heatwaves that now frequently grip large parts of France during summer months.

For supermarkets, these temperature extremes present an operational vulnerability that is becoming harder to ignore. Refrigeration systems, vital for preserving food safety and product quality, are often designed around historical climate norms, leaving them exposed to failure under today's more extreme conditions.

Systems Designed for a Climate that No Longer Exists

The increasing frequency of summer temperatures exceeding design expectations is exposing a significant vulnerability in many supermarket refrigeration systems. Traditionally, systems are engineered to meet a "design temperature" based on historical weather patterns. However, recent summers have exceeded these benchmarks across much of Europe, creating a mismatch between real-world conditions and system capabilities.

Supermarkets in Southern Europe, where daily highs often exceed 40°C during heatwaves are particularly at risk due to CO₂ performance concerns at high ambient temperatures. As a result, operators in warmer climates have reported incidents of compressor failure, circuit breaker trips, and temperature excursions leading to food spoilage and emergency refrigeration rentals (https://atmosphere.cool/atmo-market-report-2023/).

These cases underscore the urgent need to reevaluate system design thresholds and implement strategies that protect refrigeration infrastructure against the increasingly routine threat of extreme heat.

Operational Domino Effect

When refrigeration systems are pushed beyond their design limits during extreme heat, the consequences cascade rapidly across store operations. Elevated ambient temperatures force compressors to work harder, increasing energy consumption and accelerating mechanical wear.

As system pressures rise, flash gas accumulates in the suction line, leading to unstable operation and, in severe cases, high-pressure discharge failures or automatic system shutdowns. These malfunctions pose a direct threat to food safety; if refrigerated cases exceed critical temperature thresholds, supermarkets risk violating standards, resulting in potential food spoilage, regulatory non-compliance, and financial losses.

Beyond the immediate impact on product integrity, system overloads also strain operational continuity; staff must monitor and manage temperature excursions manually, organize emergency repairs, or source temporary refrigeration rentals at high cost. The cumulative effect of these outcomes illustrates the high stakes of underestimating heatwave resilience in refrigeration planning.

A Reactive Rather than Proactive Approach

This lack of adaptation for the rising frequency of heatwaves over equipment lifespan results in a predominantly reactive posture; emergency measures and system upgrades often occur only after a failure. Few supermarket chains incorporate regional climate projections or future weather scenarios into their design specifications, potentially limiting the ability of systems to perform reliably in the years ahead. Closing these strategic gaps will require a cultural shift in planning and better integration of climate science into equipment selection and system design.

Existing Solutions

There are now several options for CO₂ systems, which have gained traction across Europe as a sustainable alternative to high-GWP refrigerants, to optimize hot-weather performance and heatwave adaptability.

Traditional approaches include:

·         Mechanical subcooling, which enhances system efficiency by lowering the temperature of the refrigerant before expansion.

·         Water spray or evaporative cooling systems that reduce gas cooler outlet temperatures.

However, these methods require significant infrastructure modifications and, in the case of water-based solutions, can introduce operational challenges in regions with water scarcity or rising utility costs.

More advanced methods such as gas ejectors and parallel compression have been adopted in new installations to reduce flash gas losses and improve energy efficiency, yet they typically involve complex engineering and are less feasible for retrofits.

In contrast, pressure exchangers are a streamlined option that recovers energy to reduce compressor workload, ultimately driving both energy efficiency and increased system capacity. These compact devices can be integrated into existing systems with minimal disruption and have demonstrated notable performance improvements, particularly in warm ambient conditions.

Building a Proactive Thermal Resilience Strategy

In light of the escalating risks posed by extreme heat, supermarket operators and system designers must adopt a more forward-looking approach to refrigeration system management; beginning with conducting heat-resilience audits of refrigeration systems to identify vulnerabilities in prolonged high ambient conditions.

Relying solely on historical weather data is no longer sufficient for new builds; long-term climate projections should inform system design to ensure performance remains reliable over the full equipment lifecycle. Retailers should:

·         Establish clear performance thresholds, along with emergency protocols for system overloads or shutdowns to help mitigate operational disruptions.

·         Evaluate available retrofit technologies, such as pressure exchangers, based on their regional climate exposure and store-specific risk profiles.

As heatwaves become the new normal rather than exceptional events, investing in refrigeration resilience is no longer optional. Proactive planning not only protects inventory and reduces energy use but also safeguards business continuity and upholds food safety standards, making it a foundational component of modern food retail infrastructure.