17 February 2012: Transport for London (TfL) have issued a news release providing an update on measures being implemented to help ‘cool the tube’. The release reports that “At Green Park station borehole cooling technology will be used. London Underground has already successfully drilled wells to source naturally cool water from deep below Green Park and will now install air cooling units that will use the water to cool the Victoria and Piccadilly line platforms.” A similar ground water cooling scheme already operates at Victoria station.
High tunnel temperatures during the summer months are one of the biggest challenges facing the Tube, particularly for the deep tunnelled sections of the Underground,such as the Victoria line. These are generally closed systems where the major proportion of the energy that enters (for example, train motors) is released as heat, which in turn raises temperatures in the tunnels and on the trains. As a result of increased train service capacity (primarily through higher train frequencies) and reduced journey times (mainly through quicker acceleration and faster maximum speeds), electricity use on the Underground is anticipated to increase by 2020, resulting in more heat being released in the tunnels. This will be exacerbated by increasing passenger numbers and possible increases in air temperature due to climate change.
More recently, the Mayor’s 2011 Climate Change Adaptation Strategy (p104) details that:
London Underground’s aim is to minimise the heat generated by the existing network and planned upgrade of the service, so that further energy is not required to offset the heat that is generated. The interventions to cool temperature increases caused by the line upgrades will also help to manage the higher external temperatures caused by climate change. Optimising the energy efficiency of the service through driving the trains more efficiently will reduce the heating contribution from the operating regime.
Despite these efforts, temperatures on the Underground will continue to be uncomfortable in hot summers … projections suggest that on a summer day by the 2030s, there is a 24-27 per cent probability of temperatures being warmer than 24°C. By 2050s, this rises to 62-75 per cent and 70-91 per cent by 2080s. This compares to 11 per cent probability today.
A recent (2 February 2012) TfL Board Paper (page 21) also provides a summary update on Phase 1 of the Tube Cooling programme.