Cold Room Design & Build Guide

Most cold room enquiries arrive as a size and a temperature: "I need a 10 × 12 freezer room." That is a reasonable place to start and a poor place to stop, because the two numbers that were not mentioned — the panel thickness and what happens at the floor — will do more to decide the electricity bill for the next twenty-five years than the room's footprint ever will.

This guide walks the specification in the order it actually gets decided, then walks the build in the order it actually happens on site. It is written for a buyer who wants to hold an informed conversation with a supplier, not for a refrigeration engineer.

Quick navigation: What a cold room is · Types and temperature bands · Sizing · Wall material and panel thickness · Doors and door protection · Floors · Refrigeration · The eight build stages · What drives installed cost · Choosing a manufacturer · FAQ

What a cold room is — and what it is not

A cold room is a room-sized, insulated enclosure assembled on site from factory-made sandwich panels and cooled by a refrigeration system sized to a calculated load. Three things separate it from a large commercial fridge:

• It is built, not bought. The panels are made to length and the room is erected to your dimensions, inside your building or against it.
• It is sized against a heat load, not a catalogue capacity. The refrigeration is chosen after the envelope, the door usage and the product are known.
• It is a long-lived asset. A properly specified envelope has a design life measured in decades, which is why insulation decisions dominate lifetime cost.

"Cold room" and "cold store" are used interchangeably in the market. In practice a cold room tends to mean a walk-in room inside or attached to an existing building, while a cold store means warehouse scale — a standalone envelope with multiple chambers, dock levellers and a plant room. The engineering is the same in kind. The difference is scale, redundancy and how much civil work is involved.

Types and temperature bands

Type	Typical band	Used for	Typical panel
Chiller	+2 to +5 °C	Produce, dairy, prepared food, pharmacy	60–80 mm
Cold chiller	0 to +2 °C	Meat and fish holding, flowers	80–100 mm
Freezer	−18 to −25 °C	Frozen storage, ice cream, frozen meat	100–125 mm
Blast freezer	−30 to −40 °C	Rapid freezing of warm product	150 mm+
Dual-zone	Mixed	Chiller and freezer in one shell, split by a partition	Per zone

The distinction that catches people out is between holding and freezing. A freezer room holds product that is already frozen. It is not designed to freeze warm product, and loading warm product into one will lift the room temperature, run the compressor continuously and still produce a poor freeze. If you need to bring product down from ambient, that is blast duty and it is a different machine. The difference is covered in detail in the blast freezer versus blast chiller guide.

Sizing — start with volume, not floor area

Cold storage capacity is volumetric. A 20 m² room at 2.4 m clear height and a 20 m² room at 4 m clear height are not the same room: the taller one holds two-thirds more, and costs more to run, because every internal surface has to be insulated and every cubic metre of air has to be cooled.

Three practical constraints usually decide the final dimensions:

1. Product volume plus air. Stacked product needs air paths around it. Packing a room solid defeats the airflow the evaporator depends on and creates warm pockets.
2. Racking and access. Aisle widths, pallet dimensions and whether a pallet truck has to turn inside the room usually set the footprint more than the product does.
3. Clear height under the evaporator. The unit needs throw distance and an unobstructed return path. Stacking to the ceiling starves it.

For a first pass, the capacity planner converts tonnage of a given crop into a room volume, and the cold room builder takes dimensions and returns the resulting heat load directly.

Wall material and panel thickness

Cold room walls are double-skin sandwich panels — two steel facings bonded to a rigid insulating core and joined with cam-locks that pull the joint tight from inside. The core is the decision that matters.

Core	Behaviour	Where it fits
PIR	Best thermal performance of the three, better fire behaviour than EPS, dimensionally stable	The default for cold rooms and freezers
PUR	Similar thermal performance to PIR, weaker fire behaviour	General insulated envelopes
EPS	Cheapest, noticeably worse conductivity, poorest fire behaviour	Budget chiller work, non-critical envelopes

Izhar Foster's FireSafe PIR is specified at an aged thermal conductivity of λ 0.022 W/m·K to BS EN 14509. The "aged" part matters: rigid foams lose a little performance in their first years as the blowing agent equilibrates, and a quoted initial λ flatters the panel. Always compare aged figures. A full comparison sits in the PUF vs EPS vs PIR guide.

Thickness follows temperature, but it is really a running-cost decision. Panel U-value is λ divided by thickness, so doubling the core roughly halves the transmission load through that surface, every hour, for the life of the room. In Pakistani design ambients — 45 °C in Lahore, 48 in Multan, 50 in Jacobabad — under-insulating is expensive in a way that shows up on the meter rather than the invoice:

• 60–75 mm — chiller above 0 °C
• 80–100 mm — cold chiller or mild freezer
• 100–125 mm — standard −18 to −25 °C freezer
• 150 mm and above — blast duty, −30 °C and below

Facings are usually pre-painted steel. Food-grade or stainless facings apply where there is washdown, direct food contact or a hygiene audit involved.

Doors and door protection

The door is the single largest controllable load in most cold rooms, and the cheapest place to save a kilowatt.

Every time the door opens, cold dense air falls out of the bottom of the opening and warm humid air rolls in at the top. That air has to be cooled and, worse, dehumidified — the latent load of removing moisture from Pakistani summer air dwarfs the sensible cooling. On a freezer, that moisture also arrives as frost on the evaporator, which then needs defrosting, which puts heat back into the room.

Door protection is the fix, and the numbers are dramatic. Per ASHRAE's refrigeration load method, a strip curtain cuts infiltration by about 90% (a protection factor of 0.10) and an air curtain by about 50%. A strip curtain costs a rounding error against the refrigeration it saves. There is no good reason to omit one on a room that gets opened.

Door types:

• Hinged — the standard. Simple, reliable, seals well.
• Sliding — where there is no room for a leaf to swing, or on high-traffic openings.
• Glass display — retail visibility, at a thermal penalty.

Two details that get missed on freezers: the frame needs heater tape, or the gasket freezes to the jamb and the leaf tears when someone pulls it; and every cold room door needs an inside safety release, without exception. More on selection in the insulated doors page.

Floors — where freezer projects go wrong

The floor is the decision most often taken on price and most often regretted. Three cases:

1. Insulated floor panel on grade. The room sits on its own insulated deck. The panel sees an 18 °C soil boundary beneath it. This is the correct answer for any freezer.
2. Sealed screed on grade, no floor panel. Acceptable on a chiller: the ground settles near 18 °C and behaves as a heat sink rather than a load, and you gain a robust floor with no threshold. Not acceptable on a freezer.
3. Above grade or suspended slab. Now the floor sees ambient air, not soil. It becomes a fully loaded surface like any wall and must be insulated to match, whatever the room temperature.

The freezer-on-screed failure mode is worth spelling out, because it is common and it is expensive. A sub-zero room with no floor insulation will slowly freeze the ground beneath it. Water in that ground expands as it freezes, and the resulting frost heave lifts and cracks the slab — taking the panel joints, and sometimes the door frame alignment, with it. The remedy after the fact is to demolish and rebuild the floor.

Refrigeration — monoblock, split or remote

Configuration	What it is	Suits
Monoblock	One plug-in unit hung through the wall, no field pipework	Small chillers with power nearby; fastest to install
Split	Indoor evaporator, outdoor condensing unit, field pipework between	The general-purpose choice for most walk-ins
Remote / plant deck	Condensing units grouped away from the rooms	Multiple rooms, or where noise, heat and access rule out local units

Two Pakistan-specific points. First, condensers lose capacity as ambient rises — roughly 2.0% per Kelvin on medium temperature and 2.7% on low temperature. A unit selected at 35 °C and installed where it sees 48 °C is not the unit you thought you bought. Size against your actual design ambient, which the condenser sizing tool does directly.

Second, site the condensing unit in shade and free air. A unit boxed into a corner recirculating its own discharge, or standing in direct sun on a west wall, gives up capacity precisely during the hours you need it. This is free performance and it is routinely thrown away.

The eight build stages

This is the order a cam-lock panel room actually goes up. You can watch the same sequence animate, on your own dimensions, in the 3D cold room builder — press Watch it build.

1. Site & slab. Level slab, power and drainage set out. Flat to about ±3 mm per metre — panel joints will not pull tight on a wavy floor, and every gap left is a permanent heat leak.
2. Floor panels. Laid on the slab, joints staggered and sealed.
3. Wall panels. Stood on the floor perimeter and drawn together on cam-locks. Corners first, so the box is square before the runs close.
4. Ceiling panels. Dropped in and locked to the wall heads. Past roughly 4 m of clear span they are hung from the building steel rather than self-spanning.
5. Door & hardware. Frame, leaf, hinges, inside safety release; heater tape on any freezer.
6. Evaporator. Mounted clear of the door throw so its air pattern is not fighting the infiltration it is meant to handle. Condensate drain trapped, and trace-heated on low temp.
7. Condensing unit. Sited in free, shaded air; then pipework, electrics and controls run back.
8. Commissioning. Pressure test, evacuate, charge, set superheat, pull down and hold. Handover with the temperature log already running.

On a prepared slab, panel erection for a small walk-in is typically one to three days, with refrigeration and commissioning a further two to four. The programme is normally set by lead times on panels, the door and the refrigeration pack — and by slab readiness — rather than by the erection itself.

What actually drives installed cost

Anyone quoting a cold room price from a size alone is guessing. Installed cost moves on:

• Volume — but with strong economies of scale. On a small walk-in the fixed items (door, refrigeration pack, controls, commissioning) dominate, so per-m³ figures overstate small rooms badly.
• Target temperature — a freezer needs more panel, more compressor and a defrost strategy.
• Panel thickness and facing — see the panel price calculator for current PKR per m² and per sq ft bands.
• Floor decision — a floor panel is a real line item, and omitting it on a freezer is a false economy.
• Refrigeration configuration and redundancy — single compressor versus N+1 is a large swing.
• Site access, power supply and civil interface — slab, drainage, vapour barrier, electrical entry, generator integration.

For warehouse-scale benchmarks, the cold storage cost guide publishes per-m³ bands in PKR by application. For a small room, skip the benchmark and get the engineering first — which is exactly what the cold room builder gives you without asking for an email.

Choosing a cold room manufacturer

Questions worth asking any supplier, in rough order of how much they reveal:

1. "What λ value are you quoting, and is it aged or initial?" If the answer is vague, the panel comparison you are being shown is not a comparison.
2. "Show me the heat load calculation." A supplier who sized the plant properly can produce the transmission, infiltration and internal split. One who picked from a catalogue cannot.
3. "What design ambient did you select the condenser at?" The answer should match your city in summer, not a generic 35 °C.
4. "Does the quote include the floor, and what happens at the threshold?"
5. "Who commissions it, and what do I get at handover?" Pressure test records, charge, superheat settings and a temperature log are the minimum.
6. "What is the panel module width, and how many panels is that?" A supplier who knows the schedule knows the job.

Izhar Foster has manufactured insulated panels and built cold-chain facilities in Pakistan since 1959, as the cold-chain division of Izhar Group. If you want the calculation before the conversation, the tools below are free and ungated.

Frequently asked questions

What is a cold room?

An insulated, temperature-controlled walk-in room built from factory-made sandwich panels and served by a dedicated refrigeration system. It is built on site to the size you need and sized against a calculated heat load, rather than sold as a fixed-capacity appliance.

What material are cold room walls made of?

Double-skin sandwich panels: two steel facings bonded to a rigid insulating core and joined with cam-locks. The core is normally PIR, PUR or EPS; PIR is the standard for cold rooms because of its aged conductivity of about 0.022 W/m·K and better fire behaviour than EPS.

How thick should cold room panels be?

Roughly 60–75 mm for a chiller, 80–100 mm for a cold chiller or mild freezer, 100–125 mm for a standard −18 to −25 °C freezer, and 150 mm or more for blast duty. Treat it as a running-cost decision, not only a temperature one.

How much does a cold room cost to install in Pakistan?

There is no single figure — it moves on volume, temperature, panel thickness, floor build-up, refrigeration configuration, and site access and power. Published per-m³ benchmarks for turnkey cold storage sit around PKR 18,000–28,000 per m³ for a chiller and PKR 25,000–38,000 for a standard freezer, but small walk-ins carry a much larger share of fixed cost and do not scale down neatly.

Does a cold room need an insulated floor?

A chiller on grade can often run on a sealed screed. A freezer generally cannot: without floor insulation the room will freeze the ground beneath it, and frost heave will lift and crack the slab. Any room above grade or on a suspended slab needs a floor panel regardless of temperature.

How long does it take to build a cold room?

On a prepared slab, one to three days for panel erection on a small walk-in, plus two to four for refrigeration and commissioning. Lead times on panels, door and refrigeration pack usually govern the programme.

What is the difference between a cold room and a cold store?

Mostly scale. A cold room is typically a walk-in room in or against an existing building; a cold store is a warehouse-scale facility with multiple chambers and a plant room. Same engineering, different magnitude of civil work and redundancy.

Should I choose a monoblock, split or remote condensing unit?

Monoblock for a small chiller with power nearby; split for most walk-ins; remote or plant deck where several rooms are served from one place or the units must be kept away for noise, heat or access.

Design yours now

The cold room builder takes you through all six decisions in this guide, shows the room assembling in 3D as you go, and returns the heat load, compressor duty, annual energy, panel U-value and a panel schedule. No price gate and no email gate — you get the engineering first.