The greenest thing a stadium can do is move the kick-off time

Solar panels on a roof are a rounding error next to sixty thousand people deciding how to get home.

A stadium's own energy use is small and visible. The crowd's travel is large and invisible. Almost every sustainability announcement in sport is about the first thing.

Floodlights, pitch heating, catering, the offices, the water: run it all night and it still loses to the car park. Sixty thousand people travelling an average of forty miles round trip, a meaningful share of them alone in a car because the last train left before full time, is an order of magnitude of emissions that panels on a roof cannot touch. The panels are real. They are also a photograph.

Which is why the interesting environmental lever in stadium operations is not engineering at all. It is the fixture list.

A three o'clock Saturday kick-off in a city with a working rail service empties the ground into trains. The same match at eight on a Monday, moved for broadcast, empties it into cars, because the connections have gone and the coach operators will not run it. Nobody counts that shift in a carbon report, because the emissions belong to the supporters rather than the club, and the reporting boundaries are drawn precisely where the awkward number begins.

I would like one club to publish the comparison honestly. Same fixture, two slots, estimated travel emissions for each. My guess is the difference dwarfs everything else in the sustainability section, and that is the point of publishing it.

There is a second lever with the same shape. Away travel for the teams themselves, particularly domestic flights for journeys of two or three hours by rail, is a small volume of trips with an outsized footprint and an outsized signalling effect. A club that takes the train to a midweek away game is doing less for its own emissions than it would by rescheduling one Monday night, but it is at least a decision inside its own control.

None of this argues against the panels, the rainwater capture or the switch away from gas pitch heating. Those things are cheap now and they compound.

It argues against the accounting. If a stadium measures only what it burns inside its own walls, it will optimise the small number to a rounding error and then sell the kick-off slot that undoes the whole programme, and the report will show an improvement every single year.