If you're building a cold store in Lahore, a food-processing factory in Faisalabad, a poultry shed in Sahiwal, a pharma plant in Karachi, or a warehouse on the Sialkot bypass — your decision on building envelope is the single biggest determinant of how much you'll pay to cool that building for the next 30 years. PIR sandwich panels are the standard answer in 2026 Pakistan, but the specification matters: thickness, fire rating, facing material, joint detail, and installation quality all decide whether you get the catalogue performance or 60% of it. This is a working specification guide for Pakistani projects, written for owners, project managers, and consulting engineers.
What PIR is — and why it became the default
PIR stands for polyisocyanurate — a thermoset rigid foam made by reacting MDI (methylene diphenyl diisocyanate) with polyols, blown with pentane, and cured between two pre-painted galvanized steel facings. The result is a sandwich panel: two thin metal skins (typically 0.4–0.6 mm) bonded to a foam core typically 50–200 mm thick. The metal skins carry structural load and resist abrasion; the foam carries the thermal resistance.
The numbers that matter for Pakistani projects:
- Thermal conductivity (k-value): 0.022–0.028 W/m·K for quality PIR. Concrete is 1.4 W/m·K, brick is 0.7 W/m·K — meaning 100 mm of PIR has roughly the same insulation as 5 metres of concrete or 2.5 metres of brick.
- Density: 38–60 kg/m³, depending on the specifier. Higher density = better mechanical performance and slightly better k-value.
- Fire rating: Class B1 (DIN 4102), B-s2,d0 (EN 13501-1), or Class A flame spread (ASTM E84) for properly formulated PIR. The thermoset core chars rather than melts.
- Ozone depletion potential (ODP): Zero. Pentane blowing replaced legacy CFC and HCFC blowing agents.
- Long-term thermal drift: Less than PU foam. PIR retains 92–95% of initial k-value at 25 years; PU drifts 10–15% over the same period.
For specifications and panel ranges Izhar Foster manufactures, see the PIR sandwich panels page.
Choosing panel thickness for Pakistan
Panel thickness is the first specification decision. Match it to the operating temperature and the local design ambient — and step up one tier from European catalogue recommendations because Pakistani summer ambients are 10–15 °C above what those catalogues assume.
- Medium-temperature cold rooms (+2 to +5 °C): 80 mm for European catalogue conditions, 100 mm for Pakistan — Lahore, Multan, Faisalabad, Karachi.
- Chilled storage approaching 0 °C: 100 mm catalogue, 125 mm for Pakistan.
- Low-temperature freezers (−18 to −25 °C): 125 mm catalogue, 150 mm for Pakistan.
- Blast freezers (−40 °C): 175 mm catalogue, 200 mm for Pakistan.
- Food-processing factories with HVAC (+18 to +25 °C): 50–80 mm wall and roof — the priority is hygiene and acoustic performance more than insulation.
- Poultry sheds, dairy plants, warehouses with light cooling: 50–80 mm typical.
The cost difference between 100 mm and 125 mm of PIR panel is around 15–20% of panel cost — but the corresponding reduction in transmission load through the wall is roughly 20%, with a payback of 18–24 months on electricity savings alone in Pakistani conditions. Under-spec'ing thickness to save capex is the most common mistake we see, and it costs 10× the saved amount over a 25-year operating life.
PIR vs PU vs EPS — what each one actually does
Three insulation cores are still installed in Pakistan. The differences matter, particularly for food-grade and DRAP-regulated projects.
PIR (polyisocyanurate)
The current default for cold storage and food-grade construction. Thermal conductivity 0.022–0.028 W/m·K. Fire class B1 / B-s2,d0. Thermoset chemistry — chars rather than melts. Long-term k-value drift under 8% over 25 years. Slightly higher capital cost than PU but materially better fire and lifetime performance.
PU (polyurethane)
The previous generation default. Similar k-value to PIR initially (0.024–0.030 W/m·K) but drifts 10–15% over 20–25 years. Fire performance is weaker — most PU formulations melt and drip during fire, contributing to flame spread. Many Pakistani buildings constructed before 2018 use PU; new installations should default to PIR. The Punjab Building Code, Sindh Building Code, and DRAP audit guidance now generally favour PIR for fire performance.
EPS (expanded polystyrene)
The cheapest option, and still the dominant choice for low-temperature poultry sheds and budget industrial buildings. Thermal conductivity 0.034–0.038 W/m·K — 25–35% worse than PIR. Fire performance is significantly weaker; EPS contributes substantial flammable load and produces dense smoke. For any project subject to PFA, SFA, DRAP, or institutional buyer scrutiny, EPS is increasingly hard to defend. The capital saving (typically 20–30% vs PIR for the panel itself) is wiped out within 3–5 years by extra refrigeration energy cost.
Steel facings — the part most owners under-spec
The steel facings carry structural load, resist abrasion and impact, and define the panel's appearance and lifespan. Three specifications matter:
- Steel grade and thickness: Pre-painted galvanized steel (PPGI) or pre-painted aluminium-zinc (PPGL), typically 0.4–0.6 mm. Cold storage and food projects should default to 0.5 mm minimum.
- Zinc coating: Z180 to Z275 g/m². Inland projects (Lahore, Multan, Faisalabad) work with Z180–Z225. Coastal projects (Karachi, Port Qasim, Gwadar, Pasni) should specify Z275 minimum, or aluminium-zinc (AZ150) which performs much better in salt-laden air.
- Paint system: Polyester (PE) for general industrial, polyvinylidene fluoride (PVDF) for premium and exterior-exposed elevations, food-grade FDA-compliant paint for direct food-contact applications.
Inside cold rooms, the facing also has to be hygienic, cleanable, and resistant to standard cold-room cleaning chemicals. Stainless steel (304 or 316) facings are specified for the most demanding food-processing and pharma applications, particularly for direct-product-contact zones.
Joints, tongue-and-groove, and the cold-bridge problem
The single biggest gap between catalogue performance and real-world performance on Pakistani sites is joint quality. A 100 mm PIR panel with a poorly-detailed joint can leak 30–50% more heat at the joint than through the panel itself — wiping out half the insulation value.
Three things to specify and inspect:
- Tongue-and-groove (T&G) joints with cam-locks at panel edges, and continuous PIR core through the joint (no thermal bridge). Avoid butt joints for cold storage.
- Sealed joint cavities with closed-cell PU or silicone sealant; never leave a void at the joint.
- Vapour-tight installation with continuous vapour barriers behind warm-side facings; vapour drive in Pakistani summers is severe and uncontrolled vapour migration causes condensation inside the panel core.
What PIR actually saves you in Pakistan
For a 2,000 m³ medium-temperature cold store at Lahore ambient operating year-round:
- Bare concrete construction: baseline transmission load 18–24 kW (peak summer)
- EPS 100 mm: transmission load 4.5–6 kW — roughly 75% reduction
- PIR 100 mm: transmission load 3.0–4.0 kW — roughly 83% reduction vs bare
- PIR 125 mm: transmission load 2.4–3.2 kW — roughly 87% reduction vs bare
Translated into 2026 PKR at industrial electricity tariffs of 38–52 per kWh, the difference between EPS 100 mm and PIR 125 mm over a 25-year operating life is roughly Rs 35–55 lakh on a 2,000 m³ facility, while the panel cost premium is around Rs 4–7 lakh. The bigger the facility and the lower the operating temperature, the more dramatic the differential becomes — for a 4,000 m³ low-temp freezer the lifetime savings cross Rs 1.2 crore.
The bottom line for Pakistani projects
PIR sandwich panels have become the default specification for cold storage, food-processing, pharma, and modern industrial construction in Pakistan because the engineering math works. The right thickness, the right facings, the right zinc coating for your geography, and competent installation will give you a building envelope that performs at catalogue spec for 30+ years and pays back the panel premium in under three years through lower refrigeration cost.
The wrong specification — under-thickness panels, thin facings, butt joints, missing vapour barriers, EPS where PIR was the right call — locks you into 30 years of paying for a mistake. Talk to our engineering team if you want a panel specification matched to your project's specific operating temperature, ambient, geography, and compliance requirements.