1,200-pallet CO2 frozen store and blast freezer for a Midlands ready-meal producer

The brief

A ready-meal manufacturer in the West Midlands was outgrowing ageing refrigeration. The site ran a frozen store and blast-freeze capacity on legacy R404A plant that was becoming expensive to service as the GB F-gas quota tightened, and that sat well below the efficiency of modern natural-refrigerant systems. Two pressures were converging. Retailer volumes were rising, so the producer needed more reliable frozen capacity and faster blast throughput. At the same time, refrigeration was the single largest cost on the site, running at around £310,000 a year of electricity, and the finance director wanted that figure brought under control rather than left to climb with the R404A servicing bill.

The technical requirement was clear: a 1,200-pallet frozen store held reliably at -22°C, a blast freezer capable of two tonnes per cycle to keep pace with production, and a plant design that would pass a BRCGS audit and protect the stock against a single point of failure. The refrigerant had to be one the producer would not be forced to replace again within a few years as HFC supply was squeezed.

What we installed

We designed and built a new 1,200-pallet frozen store on a large-span PIR insulated envelope with vapour-sealed detailing and a frost-heave-protected floor, held at -22°C. Alongside it we installed a 2-tonne-per-cycle blast freezer running -35°C air-off, with high-velocity evaporator fans sized to drive the product core down fast through the ice-formation zone and protect texture and shelf life.

Both were built on new CO2 (R744) transcritical plant, chosen specifically because it sits outside the HFC phase-down and is markedly more efficient than the R404A it replaced. The plant was designed to N+1 compressor redundancy, so a single compressor failure could not lose the frozen store overnight, which had been the producer’s biggest fear with the old system. Floating head-pressure control let the plant take advantage of cooler ambient conditions to run more efficiently at part load.

We addressed the envelope and door discipline as hard as the plant. Rapid-action doors and tighter door management cut the warm, humid air admitted during goods movement, one of the largest controllable loads on a busy frozen store. On the blast freezer we fitted calibrated core-temperature probes and time-temperature logging so every cycle was recorded against the specified pull-down.

The numbers

Refrigeration electricity had been running at around £310,000 a year. The combination of efficient CO2 transcritical plant, tighter door management and rapid-action doors cut that by around £59,000 a year, a reduction of roughly 19 per cent, before any solar offset. That figure aligns with wider evidence that transcritical CO2 plant cuts energy against R404A by around a fifth.

The plant qualified as plant and machinery for capital allowances, so the producer claimed first-year relief on the qualifying capex, improving the after-tax return on the investment. Measured against the efficiency saving alone, simple payback landed at around five years; measured against the avoided cost of continuing to service scarce R404A, and the risk of a stock loss on unredundant plant, the case was stronger still.

Resilience and audit outcome

The store was commissioned with validated temperature mapping across every pallet position, confirming it held -22°C evenly with no warm spots, and the blast freezer’s pull-down was validated against its specified process with recorded core temperatures. That mapping and validation, together with continuous monitoring and alarms, made the store auditable from handover, and it supported the producer’s BRCGS temperature-control requirements.

The N+1 design changed the risk profile of the site. A single compressor failure, which on the old plant would have threatened the whole frozen store, now leaves the remaining plant holding temperature while the failed unit is repaired. For a producer whose retailer contracts depend on reliable frozen stock, that resilience was as valuable as the running-cost saving.

Cutting the bill further with solar

With the plant efficiency captured, the next lever on the biggest cost on site was offsetting the load. Because the frozen store and holding refrigeration run around the clock, the demand is flat and constant, which is the ideal profile for on-site solar: generation feeds straight into a load that is always there to absorb it, so self-consumption is high. A 250 kWp rooftop array was modelled to offset a further slice of the 24/7 refrigeration load on top of the plant efficiency already achieved. That array was scoped separately by our sister service, which specialises in solar sizing for cold storage sites against half-hourly load data.

The takeaway

Efficient CO2 transcritical plant, built outside the F-gas phase-down, cut a ready-meal producer’s £310,000-a-year refrigeration bill by around £59,000 while making the store BRCGS audit-ready and resilient to a single plant failure. It shows the pattern we build to across the cold chain: size the duty properly, choose a refrigerant with a future, design for resilience, and then attack the running cost through the envelope, the doors and load offsetting. To scope a similar project, see our cold storage cost guide and request a quote.