Due to the use of regenerative braking in the train, along with fewer bogies and thus less friction, there is a significant amount of heat not being expended through braking that otherwise would. The air cooling is putting out roughly the same amount of heat energy as being saved from the more efficient braking, resulting in roughly the same amount of heat being expended overall as the 1973 stock, requiring no major changes until train frequencies increase a substantial amount.Back when people first started mooting air conditioning for the deep level tubes, removing the heat from the platforms and tunnels was cited as a major difficulty. Was that just guff or how has the
Of course, LUL is still looking into methods of reducing the platform heat as per the experiment at Holborn disused that, with funding, will be rolled out to Knightsbridge for further live trials.
Knightsbridge hasn’t been chosen as a possible first live deployment just because it’s being upgraded, but specifically because it’s on the Piccadilly line. A lot of new trains will be arriving in a few years time, and while the trains use about 20% less power than the existing trains, and put out a lot less heat, there’s also going to be a lot more trains running on the network. More trains inevitably means more heat, and how to deal with that is a key component of the Piccadilly line upgrade project.
Although currently unfunded, TfL aims to eventually increase train frequencies on the Piccadilly line to 33 and then 36 trains per hour. It is at this point that additional cooling at five Piccadilly line stations would be necessary, according to TfL’s modelling. The five stations would be Knightsbridge, Green Park, Holborn, Leicester Square and Piccadilly Circus. TfL could then identify other locations where the panels could provide a benefit.