There is a hall in the Thames Valley with a raised floor, cable trays overhead, cooling that works perfectly and no computers in it at all. It cost something over twenty million pounds to build.
It was built on the strength of a connection offer from the network operator, and the connection offer moved by a year. Nothing is wrong with the building. The customers who signed for capacity in it are now entitled to walk away, and one or two of them will.
That is the trade in one room. The shed is easy. The power is the business.
You are selling kilowatts, and the computers belong to somebody else
A data centre is not a technology company. It is a large industrial building with a grid connection, a cooling plant, standby generators and a promise about electricity that has to hold every second of the year. Customers bring their own equipment. What they buy from you is space, power and the guarantee, usually for five years at a time.
The economics follow from that. Contracts are long, the average one bills in the low thousands of pounds a month, and customers almost never leave, because moving live systems out of a hall is painful, risky and expensive for them rather than for you. Gross margin sits at around fifty-five pence in the pound, which sounds generous until you look at what had to be spent first. Colocation and hosting are standard rated business services for VAT, so there is nothing clever to do there.
The fit-out is the whole capital story. Switchgear, transformers, uninterruptible power supplies, generators, fuel storage and cooling run into millions of pounds per megawatt, which is why the cost per square foot of fitting out a hall is far above anything else you could build. Starting at any commercially serious scale means £25,000,000, and a full campus can absorb £200,000,000. Against that, the payroll is tiny. A hall runs on a handful of engineers on perhaps £44,000 each, because the thing being sold is plant, not labour.
Britain's hosting and data processing sector is a market of the order of a few billion pounds a year spread across a few hundred operators, though both of those are estimates rather than an official series. Capacity in this trade is properly measured in megawatts, not in companies or in floor area.
There is no regulator, which is not the same as no constraint
This is one of the very few substantial British trades with no sector regulator at all. Nobody issues a data centre licence. Nobody can revoke one.
What holds the business instead is the distribution network operator, which owns the connection. You apply, you are given a capacity and a date, and that date is a statement of somebody else's engineering programme rather than a promise to you. It can move. There is no appeal, no ombudsman and no amount of money that reliably fixes it, and in parts of the country the queue for meaningful capacity is measured in years. A site with a connection is worth more than a site with a building on it.
The Environment Agency is the other body with real leverage, through the environmental permits for the standby generators and the fuel stored to run them. Those generators exist to be tested, because an untested generator is not a guarantee, and a permit problem that stops you testing quietly breaks the only thing you actually sell.
Beyond that the obligations are the ordinary ones of any large building and any firm holding data: a fire risk assessment, a written health and safety policy, a data protection fee to the Information Commissioner's Office. Customers impose more than the state does. Security certifications, audit rights and uptime clauses in the contract are negotiated, not legislated, and they bite harder. Data centres were designated critical national infrastructure in 2024, which brings the site within the scope of national security thinking without giving anybody a licence to take away.
You are judged on how much of the hall is sold
The ratio that matters is how much of the power you have installed has been sold. Everything else is commentary.
An empty hall costs almost as much to own as a full one. The building is there, the plant is maintained, the cooling runs, the rates are paid. Sell eighty per cent of installed capacity and the site is excellent. Sell thirty per cent and it is a very expensive warehouse.
Underneath that sits the cost check, which the trade calls power usage effectiveness: the total electricity drawn by the site divided by the electricity that reaches the customers' equipment. Every unit above that ratio is cooling, losses and lighting, and it is yours to pay for. A data centre is the most energy-hungry thing most people will ever run, and electricity is not a line in the overhead. It is the cost base.
The third number is not a number at all. Uptime is binary. Customers buy one promise and a single outage that takes a customer's systems down can undo a decade of selling, whatever the contract says about liability.
It dies with a hall that is cooled, lit and empty
The failure is nearly always a timing failure rather than a demand failure.
You commit a power block because a connection date says you can. You pre-sell against it, because pre-selling is how these projects are financed and nobody builds a hall on hope alone. The connection slips by a year. The customers who signed for capacity you cannot now deliver exercise their clauses and leave, taking the penalties with them. What remains is twenty million pounds of plant, working perfectly, cooled and lit and empty, with a maintenance contract and an electricity bill.
The distinguishing feature of this trade is that nothing in that sequence was a bad decision by the operator. The binding constraint was somebody else's programme.
Where this shows up in the game
In Business Baron a data centre is a capital commitment with a delivery date you do not control. The monthly decision is how much of the next hall to pre-sell before you commit the power block, and whether to take a customer who wants more kilowatts than your connection will carry, which is a bet that the upgrade lands before they move in.
The number you watch is contracted kilowatts as a share of installed kilowatts, with power usage effectiveness underneath it as the cost check. There is no regulator to appease, which players find unsettling after a few of the other trades. What there is instead is a network operator who can move a date, an Environment Agency permit that governs whether you can test the generators, and an ending in which a finished hall sits empty because the connection arrived a year after the customers needed it. The Data Centre page sets out the fit-out costs, the contract lengths and the power assumptions.
It is one of the specialist trades, and it requires the full game underneath it. It is separate because it needs two things nothing in the ordinary catalogue has: revenue contracted before the capacity exists, and a capital programme whose completion date is outside the player's hands entirely.