Iceland Cold Chain, Lahore — −28°C blast-freeze and hold store for frozen poultry export to China

Frozen chicken paws are one of Pakistan's fastest-growing agricultural export categories — a by-product of domestic poultry processing that commands strong prices in the Chinese, Vietnamese, and Southeast Asian markets where they are a valued protein source. The export value chain is simple in theory: process, blast-freeze, hold, containerise, ship. In practice, each step has a hard technical floor. And the hardest floor of all is the one that Pakistan's climate makes almost uniquely difficult to achieve: a −28°C cold chain in a city where the summer ambient hits 45°C.

Iceland Cold Chain's Raiwand Road facility was built to meet that floor — and Izhar Foster was chosen to engineer the cold-store envelope and refrigeration plant that makes it possible. This is a case study in Pakistan-specific low-temperature refrigeration engineering: where ASHRAE methods meet Pakistan climate data, and where every component selection is stress-tested against the worst week of a Lahore summer, not a European design standard.

The product and what it requires from the cold chain

Chicken paws (feet) are a high-surface-area product with no significant fat mass. This geometry is the defining characteristic for blast-freeze engineering: the surface-to-volume ratio is high, so heat extraction is fast, but the Chinese import standard requires a product core temperature of −18°C or colder — and export buyers frequently specify −20°C to −22°C as a commercial quality uplift. The blast tunnel must drive the core temperature to the target within the processing plant's cycle time. Izhar Foster sizes blast tunnel capacity against the processor's throughput in kg/hour, using ASHRAE Refrigeration Handbook product pull-down methodology with the product's specific heat and latent heat of freezing factored at the correct moisture content.

After blast-freezing, the product moves into the hold store. Hold-store temperature for export poultry is −25°C to −28°C — not the −18°C that domestic distribution cold stores use. The additional depth below −18°C is a food safety and product quality margin: at −18°C, Listeria monocytogenes growth is arrested but the product is right on the regulatory boundary; at −25°C, the protein and lipid chemistry is fully arrested for the 3–6 month ocean voyage to the Chinese market. Hold-store temperature stability matters too — fluctuation above −25°C during a load-shed event or a compressor trip can compromise the product's GACC certification, costing an export shipment its market access.

Why −28°C and 45°C ambient is the hardest refrigeration scenario in Pakistan

The thermodynamic challenge of running a −28°C cold store in a 45°C ambient is not simply "it's harder" — there is a specific, calculable failure mode that catches vendors who don't know Pakistan's climate. The evaporating temperature in a −28°C room must sit at approximately −33°C to −35°C (to maintain the approach temperature difference needed for adequate evaporator capacity). In a 45°C ambient, the condensing temperature of an ammonia system rises to 45–48°C. The resulting pressure ratio on a single-stage compressor — the ratio of absolute discharge pressure to absolute suction pressure — is approximately 12:1 to 14:1 on ammonia at these conditions. Most single-stage screw and reciprocating ammonia compressors are rated to a maximum pressure ratio of 8:1 to 10:1. Running above rated pressure ratio causes overheating of discharge gas, lubricant degradation, valve failure, and early mechanical wear.

Two-stage compression splits the ratio across two compression stages. The first stage compresses suction gas from −35°C evaporating pressure to an intermediate pressure; the second stage takes that intermediate-pressure gas (after intercooling to remove the heat of first-stage compression) and compresses it to condensing pressure. Each stage sees a pressure ratio of approximately 3.5:1 to 4:1 — well within the safe operating envelope for an industrial ammonia compressor. Izhar Foster specifies two-stage for all LT applications where room temperature is −20°C or colder in Pakistan's northern cities, and flash-intercooled single-stage as a minimum on −18°C applications in peak-summer locations. There is no thermodynamic shortcut here: the physics of the refrigerant determine the operating limits, not the vendor's commercial preference.

The 150 mm PIR envelope — why thickness matters at LT

For a −28°C hold store in a Lahore 45°C summer ambient, Izhar Foster specifies a minimum of 150 mm FireSafe PIR on all six faces. The thermal arithmetic is straightforward: at 150 mm with our PIR's λ = 0.022 W/m·K (BS EN 14509 aged value), the wall U-value is approximately 0.13 W/m²K. The temperature difference across the envelope at peak summer is 73 K (45°C minus −28°C). The heat ingress per unit wall area is U × ΔT = 0.13 × 73 = 9.5 W/m². For a mid-size hold store of, say, 1,500 m² total envelope area, that is 14.2 kW of steady-state heat ingress through the fabric alone — a number the refrigeration plant must overcome continuously. Reduce panel thickness to 100 mm (U = 0.20 W/m²K) and the fabric load rises to 21.9 kW — a 54% increase that directly sizes the refrigeration plant larger and operates it harder for its full 25-year life.

The panel joint is often the weakest point in a −28°C envelope. At a 73 K delta-T, any gap in the insulation layer — even a hairline — drives intense moisture vapour migration from the warm side to the cold side. The vapour deposits as frost, which expands the gap, which accelerates the ingress, in a progressive failure mode. Izhar Foster's FireSafe PIR panel joint uses a positive mechanical interlock that maintains zero-gap contact through full thermal cycling — from the +40°C surface temperature of the outer face in summer sun to the −28°C inner face. This is not a feature that commodity panel suppliers routinely deliver; it is an engineering detail that matters enormously at LT, and not at all at +4°C.

Power resilience for an export cold chain — the GACC certification risk

Pakistan's grid reliability is improving, but export cold chains have a specific vulnerability: temperature excursion during a load-shed event can invalidate the GACC export certification for a batch of product. A hold store at −28°C has significant thermal inertia — it does not warm instantly when the refrigeration plant trips — but a prolonged power interruption without generator backup is a regulatory and commercial catastrophe for an exporter whose batch was certified at −25°C core temperature and is now warming.

Izhar Foster specifies generator-backed power for all LT export cold chains as a standard, not an option — with automatic transfer switching that connects the generator to the compressor room within 30–45 seconds of grid loss. The generator set is sized against the full-load running current of the refrigeration plant, not just the controls. Compressor soft-start units prevent the inrush current spike from tripping the generator under-voltage protections at start-up. Controls and temperature monitoring are UPS-backed on a separate circuit, so the data logger continues recording core temperature through the generator switch and provides a continuous audit trail for the GACC documentation package.

Frozen poultry export — Pakistan's cold-chain growth opportunity

Pakistan produces approximately 2 billion broiler birds per year — and the export of by-products, principally chicken paws, to Chinese and Southeast Asian markets has grown significantly over the last decade. The constraint on growth is not demand (Chinese buyers are actively sourcing Pakistan paws) but cold-chain infrastructure: there are not enough GACC-certified −25°C cold stores with blast tunnels near Pakistan's major poultry processing clusters. Lahore's Raiwand Road corridor — home to major poultry processors — has historically lacked the concentration of low-temperature cold-store capacity that a mature export supply chain requires.

Iceland Cold Chain's facility addresses that gap directly. It is not the only LT cold store in the Raiwand Road corridor, but it is one of the most precisely engineered — because the export quality specifications, the regulatory documentation requirements, and the summer ambient conditions leave no tolerance for a refrigeration plant that is merely adequate. The GACC certification process requires documented blast-freeze schedules, calibrated core temperature probes, and continuous hold-store temperature records: Izhar Foster's monitoring and controls system generates all of this as a standard deliverable.

If you are planning a −25°C or −28°C cold store for frozen poultry or fish export in Pakistan, start with our cold room heat load calculator — input your room dimensions, target temperature, and city, and get a sized refrigeration estimate with Pakistan-specific climate data. Then request a quote for a full concept and indicative budget. Our engineers respond within 24 hours.

Specification context — −28°C export freezer, Lahore

Parameter	Iceland Cold Chain specification
Hold temperature	−28°C
Blast tunnel air temperature	−35°C, high-velocity forced air
Product core target	−18°C min (GACC); −20°C to −22°C commercial spec
Ambient design DB (Lahore)	47°C (ASHRAE 0.4% + Pakistan +2 K uplift)
Panel — walls and ceiling	150 mm FireSafe PIR; U ≈ 0.13 W/m²K
Panel λ value	0.022 W/m·K (BS EN 14509 aged)
Refrigerant	Ammonia (NH₃) — zero GWP, zero ODP
Compression	Two-stage ammonia with intercooling
Condenser derate	2.7%/K above 35°C ambient; hard floor 60%
Temperature monitoring	Continuous calibrated probes; GACC audit trail
Power	Generator-backed with ATS; UPS on controls