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OK, SO NOW we have a national hosepipe ban. Our reservoirs are low, and the number doing the rounds is that Ireland’s data centres drank roughly a billion litres of water last year; seemingly, this is about the same as Sligo town. I think it sounds like a good number and so it lands.

I read a piece here in The Journal recently that made an argument I mostly agree with. Yes, the sector is opaque. Ireland has been slow and grudging in transposing its EU reporting obligations, to the point of an infringement case. Yes, it seems a secrecy provision drafted by lobbyists ended up in our regulations. All of that is true, and all of it is indefensible, and I have no interest in defending it.

But I want to ask the awkward follow-up question. Suppose we win. Suppose every facility in the State publishes its litres and its kilowatt-hours tomorrow, all of them audited, facility-level, no aggregation, no commercial-sensitivity dodge. What, precisely, do we then do with it?

I think we would do what we already do. We would hold the number up beside a town, or a county’s worth of homes, and feel that an argument had been made.

It hasn’t.

It is single-entry bookkeeping. We have built ourselves a very detailed debit column and no credit column at all, and then we wonder why the accounts never resolve into a decision.

I have spent 20 years in and around public procurement, which is a field that made exactly this mistake and eventually grew out of it. For decades, we awarded contracts to the lowest price, because price is the number you can verify, defend at audit and print in a headline.

Then we learned the expensive way that the cheapest tender can frequently be the dearest asset. We find that it fails early, it costs a fortune to run, it locks you into a supplier, and it has to be replaced by someone else’s successor.

So the discipline moved, slowly, painfully, to whole-life costing. Not because price stopped mattering, but because price on its own could not tell you whether you had made a good decision.

Consumption figures are the purchase price of the data centre debate. Real, verifiable, and nearly useless standing alone. Consider what sits in the column we are not reading. Everyone in this argument now cites the EU Energy Efficiency Directive, and everyone cites Article 12.

This is the reporting obligation, the database, the coming rating scheme. Almost nobody cites Article 26, which is in the same directive and requires facilities above a megawatt to recover and use their waste heat unless they can show it is genuinely infeasible. Article 12 tells you the size of the problem. Article 26 tells you to stop wasting it.

We have precisely one serious example. The Tallaght district heating scheme takes waste heat from a nearby Amazon facility and uses it to heat South Dublin County Hall and the TU Dublin campus, run by a not-for-profit utility owned by the council, cutting something close to 1,500 tonnes of CO2 a year. It is the only scheme of its kind in Ireland or Britain. We know there is enough waste and renewable heat in Dublin to heat the equivalent of 1.6 million homes, and the thoughts of that should keep us all awake at night.

We have one scheme. That is a scandal, and I would argue it is a larger one than the disclosure regime, because it is a scandal about something we could already have had while we were busy arguing about litres.

The other thing our single number misses is that the rules changed underneath us. Last December the Commission for Regulation of Utilities decided a new connection policy for large energy users, now working through EirGrid’s connection process.

New facilities at or above 10 MVA must bring their own separately metered dispatchable generation or storage, sized to match their import capacity for the life of the connection, and bid it into the wholesale market.

Anything at or above 1 MVA must meet 80% of annual demand from new, additional, indigenous Irish renewables. The obligation cannot be discharged by buying up green attributes that already exist. And there is a flat prohibition on connections in constrained areas.

You may think that is too little or too late. But it is not nothing, and it is not “no meaningful restriction”. Much of our public conversation is still litigating 2021.

Here is the part that should worry anyone who actually cares about emissions rather than about winning the argument. The industry’s favourite metric, Power Usage Effectiveness, is quietly running out of road, and so is ours.

As the grid decarbonises towards 80% renewable, the operational share of a data centre’s carbon footprint shrinks and the embodied share – the silicon, the steel, the concrete, the cooling plant, the disposal, becomes the dominant term. The most consequential sustainability question you can put to a hyperscaler in 2026 is not how many litres it used in July. It is how long it keeps a server before it skips it. Nobody is asking. Nobody is required to answer.

The heat these buildings pay to throw away is hot enough, some researchers now argue, to pull carbon out of the air and turn seawater into drinking water. Nothing like that exists at scale yet. It shows though how much we’ve filed under “waste” simply because we never built a way to count it.

So for me, this is not a plea for less scrutiny. It is a plea for more. I would go considerably further than the transparency case. Give me facility-level data on embodied carbon, on server refresh cycles, on heat recovered versus heat dumped, on whether a renewable contract added a megawatt to the grid or merely relabelled one.

That is a far more uncomfortable ask than litres, and the sector would fight it far harder, precisely because it is the ask that would change behaviour.

A single number can only ever yield a single verdict, too much, or not too much. That is the argument we have been having for five years, and it has not moved an inch.

So yes, publish it all. Then tell me how much heat was recovered and how much went up into the sky, how long the servers lasted before they were skipped, and whether a single new megawatt of Irish wind exists because that building got built.

Those are questions with answers we could act on. Everything else is just a number to argue over.

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