A refrigerated container already is a cold room — an insulated steel box with a refrigeration unit built into one end — so using one as a fixed, permanently sited cold store is less a conversion than an installation. There is no structural work: you site the unit, connect it to power, fit it out inside, and it holds temperature like any walk-in. This guide covers permanent siting, the electrical connection, interior fit-out with shelving and strip curtains, how a reefer compares with a masonry-built cold room, and why it stays a reversible, resaleable asset. All prices are ex VAT, with VAT charged at 20%.
What “converting” actually involves
Because the box arrives finished, converting a reefer to a fixed cold room means very little cutting or building. The insulation is already there in the walls, floor and ceiling; the Carrier, Thermo King, Daikin or Star Cool unit is already fitted; the temperature range is typically -25°C to +25°C in standard spec, so the same box serves as a chill room or a freezer room by setting the thermostat. What you add is what turns a shipping unit into a working store: a solid base, a permanent power feed, internal racking and a door setup suited to frequent access rather than sea crossings. Keep the machinery end accessible, leaving clearance for servicing and airflow.
Siting it permanently
A permanent cold room has to sit on firm, level ground that carries the loaded weight. Empty, a 20ft weighs about 3,000 kg and a 40ft high cube about 4.5 tonnes; loaded, a 20ft can reach roughly 27 tonnes. Concrete or established hardstanding works; soft ground does not. Level matters as much as bearing: the unit drains defrost and condensate water by gravity, and the doors seal only on a true frame, so pack the four corner castings on timber baulks or steel plates where the surface is uneven. Siting a container may be subject to local planning rules — confirm with your local authority if you are unsure. Our guides cover access and ground bearing in detail.
Connecting it to power
The standard connection is three-phase 380/400 V through a five-pin 32 A CEE plug, with some small formats on single-phase 230 V; the unit draws 5 to 12 kW while running. Running consumption depends on the format and the setpoint, indicatively 70 to 170 kWh a day across the range, so the electricity tariff — not the purchase price — drives the long-term cost of a cold room that runs continuously. If three-phase is already on site the connection can cost little; if not, budget for an electrician to bring a supply to the unit before installation.
Fitting out the interior
Interior space is smaller than the outside suggests, because the insulation is thick. A 20ft measures about 5.44 × 2.29 × 2.27 m inside; a 40ft high cube runs about 11.58 × 2.29 m with 2.55 m of headroom. Fit it out for the goods and the traffic:
- Shelving and racking — free-standing or wall-fixed, sized to leave an air gap at the walls and under the ceiling so cold air circulates around the unit’s discharge.
- Strip curtains at the door cut the cold loss and frost every time someone walks in and out, which matters far more on a busy static store than on a sealed transport unit.
- Floor — the T-bar aluminium floor is built for pallet loading; add anti-slip matting for foot traffic if staff are in and out on a chill setting.
Keep goods clear of the evaporator at the machinery end so the airflow is never blocked.
Reefer versus a built cold room
| Refrigerated container | Built (masonry/panel) cold room | |
|---|---|---|
| Installation | Delivered finished, craned into place | Constructed on site |
| Insulation & unit | Built in | Panels plus a separately installed plant |
| Structural work | None | Building work |
| Movable | Yes — relocate or sell | No — fixed to the site |
| Resale | Used market, graded by class | None as a unit |
| Best for | Temporary, movable or budget-led stores | Fully bespoke fit in a building |
Neither is simply better. A built room is made to measure and disappears into an existing building; a container is a self-contained unit you can move or sell.
Reversibility and resale
The strongest argument for the container route is that little is lost if plans change. A masonry cold room is a sunk cost the day it is built. A reefer stays an asset: unbolt the racking, disconnect it, and it can be craned out and relocated or sold on the used market, where units are graded class A, B or C and a sound used unit holds 10 to 15 years of service life. UK used units are observed at £4,500 to £7,500 ex VAT and new one-trip units at £18,995 to £22,500 ex VAT; if the need is short-lived, hiring from around £12 a day ex VAT — minimum periods of about 90 days are common — avoids owning the asset at all. The prices page sets out the full picture.
Who it suits
A static reefer cold room suits anyone who wants cold storage without building work: a farm shop, a caterer, a florist, a brewery, a site that has outgrown its chillers. If you need a bespoke room integrated into a warehouse and never expect to move it, a built room may serve you better. When you know the format and the setpoint, describe your requirement once and we pass it to specialist suppliers, who contact you directly if they can meet your need.
Frequently asked questions
Can a refrigerated container be used as a fixed cold room?
Yes. A reefer is already a fully insulated box with an integrated refrigeration unit, so used as a static cold store it simply stays in one place and stays connected. Sit it on firm, level ground, wire it to a suitable supply, fit it out with shelving, and it works as a walk-in cold room with no structural conversion. It runs as a chill room or a freezer room depending on the setpoint.
How is a static reefer connected to power?
The standard connection is three-phase 380/400 V through a five-pin 32 A CEE plug, with some small formats on single-phase 230 V. The unit draws 5 to 12 kW while running. If three-phase is already on site the connection is straightforward and can cost little; if not, running a new supply to the unit is an electrician's job worth pricing before installation rather than after.
Reefer or a built cold room — which suits me?
A built cold room is fixed and made to measure, and suits a permanent layout inside an existing building. A refrigerated container arrives as a finished insulated unit, needs no construction, and can be relocated or sold on later. For a temporary, movable or budget-led cold store the container often wins; for a fully bespoke fit inside a warehouse, a built room may serve better.
Does a fixed cold room container need ATP certification?
No. ATP is a standard for temperature-controlled road transport, not for a container installed and left in one place. A static cold store carries nothing on the road, so ATP does not apply to it. Food storage may fall under hygiene rules such as HACCP, which vary by country and premises, so check the requirements that apply to your use with your local authority.