The argument that spare office cooling capacity could be the solution for overheating on the London Underground (23 May, page 11) is fatally flawed.

The time when the tube needs the most cooling is also when offices do. There surely would be no excess!

One option would be to use ice storage, but this is expensive and needs a lot of space. If CHP units were used, space for generators and for heat rejection would be an issue.

Chilled water doesn’t transport easily over distances so only buildings near tube stations could provide cooling, which seems unfair. Furthermore, demand for heating and hot water drops significantly in the summer, which is out of sync with regular generation.

Cooling trains using energy dissipated when braking is a better option. To cool stations we’d have to overcome the fact that unless these environments can be sealed we’d be throwing energy down the drain. In trying to save energy, this cannot be the way forward.

Robert Thorogood, chief technology officer, Hurley Palmer Flatt