Transport for London (TfL) is trialling a state-of-the-art cooling panel on a disused platform at Holborn station to test its suitability for reducing temperatures on the deep Tube network.
TfL's trial comes as the UK experienced its hottest temperatures on record earlier this week. The cooling panel aims to provide cooler air to passengers waiting on platforms, as well as mitigating potential temperature increases associated with running an increased number of trains on the Piccadilly line, as part of the line's future capacity upgrade.
The cooling panel works by circulating cold water around pipework within a curved metal structure to chill it. It then circulates air, using an industrial-sized fan, through gaps in the panel's structure, which in turn is cooled.
The panel could also have the additional benefit of halving operational and maintenance costs, compared to existing technology used to manage temperatures on Tube lines.
The aim of the new cooling panels is to significantly out-perform the existing Platform Air Handling Units, which are currently installed at some stations on the deep Tube network. Initial results show that the new cooling panels are much better equipped to operate in the unique conditions of the deep Tube environment.
The convection cooling system has been designed by TfL and developed by SRC Infrastructure, which also managed its build.
Following the trial at Holborn station and subject to funding being available, TfL will explore whether the panels could provide a cooling solution for other deep Tube lines in the future.
Further testing would need to take place in a station open to customers (Knightsbridge) before TfL could look to potentially introduce them at four additional stations on the Piccadilly line (Green Park, Holborn, Leicester Square and Piccadilly Circus).
The Piccadilly line was chosen for this trial as when new, air-conditioned trains with walk-through carriages are introduced to the line from 2025, the current fleet will be gradually withdrawn from service and the frequency of trains in peak hours will rise from 24 to 27 trains per hour from mid-2027.
This is a train every 135 seconds at the busiest times and represents a 23 per cent increase in peak service capacity.
In the past it has been challenging to lower temperatures on the deep Tube lines, as traditional cooling systems have proved prohibitively expensive and difficult to install within the 120-year-old tunnels and stations.
In recent tests on a prototype cooling panel in a lab environment, an air temperature reduction of 10-15 degrees in the vicinity of the panel was achieved.