London’s tube system is literally heating up the city – and that’s a problem. A hundred years ago their subway stations were places to cool down during hot summer days and people had to wear sweaters while commuting. Today, this is no longer the case. The trains are heating the earth which in turn makes the entire tube too hot.
Cooling the tube is now a pressing issue and nifty ideas are being tried. New systems being tested tend to be green and benefit other parts of the city. Basically they are trying to transfer the heat to places that want it to save costs.
An experiment in Islington is trying that very thing using heat from the tube tunnels to warm up a municipal heating service provided to a housing estate. The advantage of this scheme is that it can remove heat in winter when it’s needed above ground. It may seem mildly annoying that surface users don’t want heat in summer when you’d think the tunnels are at their most oppressive, but in fact removing heat in winter helps during the summer.
If the clay surrounding the tunnel can be cooled in winter, it has more capacity to absorb heat in the summer.
As it happens, at this particular trial, the fans can also be reversed so that during the summer months, they can suck cool night time air down into the tunnels as well.