You've probably seen some of them around too. Escalators are switched off at quieter times of the day to save energy & "help lower the temperature" (not that the temperature needed much lowering in November).
I wonder how many stations this actually happens at? There must be some high traffic stations like Tottenham Court Road, Holborn and Angel which have pretty long escalators. But I'm sure the escalators there are never turned off.
Also why do some Tube stations which are open air and have large glass ticket halls have all of their lights on, all of the time? The Guardian questioned TfL about the lights at Stratford Tube in the summertime & although there was a standard "we're reviewing this" comment, there's no update as to whether anything was done.
Lights behind advertising hoardings on platforms and in corridors also seem to be constantly on & there's no mention of them being turned off at quieter times during the day. This is particularly annoying if there's no ads in them!
Do you have any other suggestions as to how the London Underground could save energy? Have you seen any other energy saving initiatives on networks outside of London?