At Wessex Refrigeration Hire, we are obsessed with efficiency. Whether we are providing a temporary cold room for a festival or a long-term pharmaceutical freezer, we want to help you run it as effectively as possible. So, let’s dive into the science, the history, and the potential for freezer temperature efficiency.

The Origins of -18°C

The standard of -18°C didn’t just appear out of thin air. It actually dates back to the early days of modern refrigeration in the United States. The influential American Society of Refrigerating Engineers settled on 0°F as a nice, round number for frozen food storage. When this was converted to Celsius, it came out to -17.78°C, which was rounded to -18°C.

Europe eventually adopted this standard in the 1960s (specifically via the EC Directive on Quick Frozen Foodstuffs in 1989), solidifying -18°C as the global benchmark for frozen food safety.

But does “standard” mean “optimal”? Not necessarily. While it provides a safe buffer, keeping units at this specific temperature requires significant energy.

The Case for -15°C: A Move Toward Energy Efficiency?

Recent studies and industry discussions have started to challenge the strict adherence to -18°C. The logic is simple: the colder you keep a freezer, the harder the compressor works, and the more electricity it consumes.

Research suggests that for many types of food, raising the temperature by just 3 degrees to -15°C could result in significant energy savings—potentially a 10% to 15% reduction in energy consumption—without compromising food safety.

Why -15°C Might Be Enough

For many products, the difference between -18°C and -15°C is negligible in terms of bacterial growth. At -15°C, water activity is still sufficiently low to prevent microbial proliferation.

• Food Safety: Bacteria generally cannot grow below -12°C. Therefore, -15°C still provides a healthy safety margin.

• Quality: For short-to-medium term storage (typical in high-turnover commercial kitchens or events), the textural changes in food between these two temperatures are often undetectable.

If you are running a large bank of freezers or a massive walk-in unit, a shift to a slightly higher set point could mean saving hundreds or even thousands of pounds a year on your energy bill.

When -18°C (or Lower) Is Absolutely Essential

Before you rush to adjust your thermostat, it is crucial to understand that -18°C isn’t just arbitrary for everyone. There are specific scenarios where sticking to the optimal freezing temperature of -18°C or lower is non-negotiable:

1. Long-Term Storage: The colder the temperature, the slower the chemical reactions. For food stored for many months or over a year, -18°C helps retard oxidation (which causes rancidity in fats) better than -15°C. If you are stockpiling inventory for the long haul, colder is better.

2. Ice Cream and Gelato: Ice cream is incredibly sensitive to temperature fluctuations. At -15°C, ice cream can become too soft, leading to ice crystal formation when it refreezes. To maintain that perfect, creamy texture, ice cream often needs to be stored at -18°C to -20°C.

3. Food Regulations & Compliance: For many businesses, you simply don’t have a choice. Current UK and EU regulations for “Quick Frozen Foodstuffs” mandate that the internal temperature of the food must be maintained at -18°C or lower throughout the cold chain. Until these regulations evolve, commercial operators must comply to pass audits.

Energy-Saving Freezer Tips You Can Use Today

Whether you stick to -18°C for compliance or experiment with -15°C for non-regulated stock, there are plenty of other ways to improve your freezer temperature efficiency:

• Keep It Full: A full freezer retains cold better than an empty one. If you have a large walk-in that’s only half full, the unit has to work harder to cool the empty air every time the door opens.

• Check Your Seals: Damaged door gaskets are the number one enemy of efficiency. If warm air leaks in, your compressor runs overtime, and ice builds up on the evaporator.

• Defrost Regularly: If you don’t have an automatic defrost cycle, keep an eye on ice buildup. Excess ice acts as an insulator, preventing the evaporator coils from absorbing heat efficiently.

• Install Strip Curtains: For walk-in freezers, PVC strip curtains are a lifesaver. They minimize the amount of cold air that escapes when your staff enters and exits.

Need Expert Advice on Your Setup?

Navigating the balance between energy costs and food safety can be tricky. At Wessex Refrigeration Hire, we supply high-efficiency, German-engineered cold rooms and freezers that are designed to keep your running costs low, whatever set point you choose.

Whether you need a temporary blast freezer to rapidly cool produce or a long-term frozen storage solution, we are here to help you configure it for maximum efficiency.

Do you have questions about the most efficient setup for your business? We’d love to help!