A few years ago I looked at a group that had fitted walk-in cold rooms across sixteen sites over about four years. Different contractors, no central specification, each site signed off locally by whoever was managing it at the time. Sixteen cold rooms, eleven different condensing units, four controller brands, and panel thicknesses ranging from 75mm to 100mm depending on what was in stock that month.
Every individual decision had been sensible. The result was an estate nobody could maintain efficiently, hold spares for, or compare energy performance across. The savings made at each install were spent several times over in the years afterwards.
Standardising a cold room programme is not glamorous work. It is one of the highest-return things a multi-site operator can do, and it costs almost nothing beyond the discipline of writing the specification down before you start.
Why standardisation pays more than a good unit price
The argument for a single specification is not aesthetic. It is operational.
- Spares. One controller brand across the estate means one set of spares, and an engineer who can carry the right part rather than order it.
- Engineer familiarity. The second time someone works on an identical system, diagnosis is faster. That compounds across an estate.
- Comparable data. If every site has the same kit, energy and fault data become genuinely comparable, and an outlier site actually means something.
- Negotiating position. Buying sixteen identical systems is a different conversation from buying sixteen one-offs.
- Compliance simplicity. Same refrigerant, same charge, same CO₂e band, same leak check frequency. That is one line in a register instead of sixteen calculations.
The one thing standardisation must not become is a refusal to survey. The specification sets the standard. The survey decides where a site genuinely cannot meet it.
What a cold room specification actually contains
If you write nothing else down, write this. It is the document you send with a tender and the document you hold a contractor against on handover.
| Element | What to specify |
|---|---|
| Operating temperature | Design temperature and tolerance, chilled and frozen stated separately |
| Panel construction | Thickness, core material, finish, food-safe surface |
| Floor | Insulated floor or sealed to existing slab, load rating, finish, threshold detail |
| Doors | Size, hinged or sliding, heated frame on freezers, closer type, vision panel |
| Refrigeration | System type, refrigerant, condensing unit location, remote or integral |
| Controls | Controller make and model, defrost strategy, alarm outputs, remote monitoring capability |
| Monitoring | Temperature logging method, alarm routing, who receives out-of-hours alerts |
| Safety | Internal door release, internal lighting, trapped-person alarm where risk assessed |
| Electrical | Supply requirement, isolation, whether the contractor or your electrician provides it |
| Drainage | Condensate route, trap detail, heater tape on freezer drains |
| Handover | Commissioning sheet with readings, O&M manual, asset data in your format |
Two of those get skipped constantly. The last one is how you end up with an estate you cannot register properly. The safety row is how you end up with a serious incident.
Build the safety requirements into the spec, not the snag list
The HSE guidance on chilled and frozen products is direct about entrapment. It says to "provide means of escape following entrapment inside walk-in refrigeration units, chill units and freezers", that "doors should be openable from the inside and lighting or other means provided to enable the door and opening device to be seen when the door is closed", and that "your risk assessment may show trapped-person alarms are appropriate".
None of that is expensive at design stage. All of it is awkward to retrofit across sixteen live sites. Put internal release, internal lighting and alarm provision in the base specification and it simply arrives with every unit. We have covered the detail of cold room entrapment alarms separately.
The same page notes that for chillers around 0°C suitable clothing and normal breaks are usually sufficient, but for blast freezers at -30°C "no personal protective equipment (PPE) will be sufficient and breaks at ambient temperature or in warming rooms will be needed". If your rollout includes low-temperature rooms where people will work for sustained periods, that is a working practices question, not just an equipment one.
The survey items that get missed
Almost every cold room programme overrun I have seen traces back to something nobody checked before ordering. These are the recurring ones.
Access route, not just the room
Panels have to get from the van to the room. Through a trading floor, up a stair, round a corner, through a doorway that was measured after the panel size was fixed. Measure the route, not just the destination.
Floor loading and level
An insulated floor on an uneven slab needs levelling first. A freezer room on an upper floor raises loading questions that need answering by someone qualified to answer them. Neither is a problem if it is found in a survey. Both are a problem if found on install day.
Where the condensing unit goes
This decision drives more of the long-term cost than almost anything else in the specification. A condenser in a hot, greasy or enclosed location fouls faster, runs at higher head pressure, uses more electricity and shortens compressor life. A condenser somewhere nobody can safely reach will not get cleaned, which produces the same result more slowly.
Ask two questions of every proposed location. Will it get adequate airflow at the hottest hour of the hottest day, and can an engineer reach it with a ladder and a hose without a permit. If either answer is no, move it or budget for the consequence.
Ambient conditions in the space
A cold room built into a kitchen with no ventilation behaves differently from the same room in a cool store area. Design ambient matters. So does humidity, which drives icing and door frame condensation. Where humidity is a known issue, our guide on humidity control in cold rooms covers what actually helps.
Drainage
Where does the condensate go, and on a freezer, is the drain heated along its full run. A frozen drain line produces an ice build-up that presents as a door that will not close, which presents as a temperature failure.
Insulation, and why the thickness argument matters
Panel thickness is where value engineering usually strikes, because it is the easiest line to cut and the effect is invisible on day one. It is not invisible on the electricity bill, and the load runs every hour for the next fifteen years.
Specify the thickness centrally and hold it. If a site genuinely cannot take the specified panel because of a space constraint, that is a documented exception with a known consequence, not a silent substitution. Our explainer on cold room insulation goes into how panel performance actually affects running cost.
Tendering the rollout
A rollout tender is a different document from a single-install quote. What you want back is not just a price.
- Price per site, broken down. Room, refrigeration, electrical, builders' work, commissioning, listed separately so you can see where sites differ and why.
- Named equipment. Not "or similar". If a contractor wants to propose an alternative, that is a conversation, not a substitution right buried in a quote.
- A programme. Sequence, duration per site, and what happens to trade during the works.
- Out-of-hours working priced in. If sites cannot close, night and early-morning working is the base case, not a variation.
- Company F-Gas certification evidenced. Certification applies to the undertaking, not only to individual engineers.
- Commissioning documentation format agreed up front. Readings, not a signature.
- Asset data in your register format. Make, model, serial, refrigerant type and charge, per site, delivered as a file you can use.
That last point is worth insisting on because it costs the contractor almost nothing at the time and saves you a survey later. Without refrigerant type and charge, you cannot calculate CO₂e, and without CO₂e you cannot know your leak check frequencies.
On the certification point, our guide to assessing a refrigeration contractor for a multi-site estate covers what to verify and how, including the subcontracting question if you are buying through a national provider.
Sequencing a rollout across trading sites
The engineering is usually the easy part. The programme is where these go wrong.
- Do one site first and leave a gap. Build the first room, run it for three or four weeks, and let the snags surface before you commit the other fifteen to the same design. This single step catches more problems than any amount of design review.
- Sequence by trading pattern, not by geography. Quietest sites first, so the team is fully up to speed before it reaches the difficult ones.
- Plan the stock, not just the works. Where does product live while the room is down, and who is paying for hire cabinets or transfers.
- Fix the handover pack before site one. If you agree the documentation format after the first install, you will chase the first five forever.
- Book the first service before the warranty period ends. New equipment still needs its first planned visit, and the easiest time to agree that is while the final payment is still outstanding.
What the finished estate should look like
When a rollout has been done properly, you should be able to answer these without ringing anybody: what is installed at each site, what refrigerant it holds, what its CO₂e charge is, when it was commissioned, what its commissioning readings were, when its next leak check is due, and who to call at 3am. If you can answer all seven, the programme worked. If you cannot answer any of them, the units may well be fine and the estate is still not under control.
We install and service cold rooms across London and the South East, including multi-site programmes, and we would rather have the specification argument before the order than the snagging argument after it. You can see our cold room installation work, look at projects we have delivered, or talk to us about a rollout.
About the author: Ali Elm runs Be Cool Refrigeration & Air Conditioning, a family-run London firm that has been installing, servicing and repairing commercial refrigeration and air conditioning since 2004. His F-Gas certified team has delivered more than 2,000 projects across London and the South East.
Written by
Ali Elm
Ali is the Head of Operations at Be Cool Refrigeration with over a decade of hands-on experience in HVAC and commercial refrigeration. He oversees every installation, repair, and maintenance project, making sure the work meets the highest standards. Ali holds full F-Gas certification and has worked across residential, commercial, and industrial refrigeration systems throughout London and the South East. When he is not on site, he writes these guides to help business owners and homeowners understand their cooling systems better.