Keeping Cool on the Tube – The Trouble With Deep-line Air Con

The September 2016 heatwave reminded London commuters of a problem that has plagued the Underground for most of its history. Poor ventilation on its deep-level networks meant that temperatures as high as 35°C, or 95°F, were recorded on the Central Line, and this lead to new calls to find a solution to the capital’s sweltering Tube lines.

The Problem With Air Con on the Underground

Many have cried, ‘fit air con in the trains!’ but the problem with fitting air conditioning on deep-level trains is that it would cause the entire network to become hotter. On certain lines, the train doors are open longer than they are closed, due to how frequently the train stops. Air conditioning might cool the carriages briefly, but they would spill the cool air onto the platforms when the doors opened.

This would cause a domino effect as the air conditioning units worked harder to maintain a cooler temperature in the carriage, which would mean hotter exhaust temperatures from the units outside the train. The Victorian-built lines have suffered poor ventilation since their creation, but the heat from air conditioning would truly overburden the already poor ventilation on the deep-level lines. In other words, the oldest underground railway system in the world is showing its age, and the costs of modifying the existing infrastructure makes it virtually impossible to improve it using current technologies.

Sub-surface lines, such as Hammersmith & City and Metropolitan, are much closer to the surface and have larger tunnels than the deep-level lines. This makes them naturally cooler, but their modern affordances mean that air conditioning on trains is an option, and it is an option that Transport for London have taken gladly. Trains on sub-surface lines are perfectly cool, even during the most blistering heatwave. And this selective approach to air conditioning on the Tube network has left many commuters scratching their heads in frustration. Unfortunately, the issue of cooling the Tube does not have a ‘one size fits all’ solution.

Innovative Air Con Solutions

In 2003, then Mayor of London Ken Livingstone offered £100,000 in prize money to anyone who could produce a feasible concept to cool the deep-level Tube lines. But no serious designs were forthcoming and the competition ended in 2005. Another effort was made in 2006, when Engineering Students at London South Bank University successfully demonstrated a prototype cooling system, and a year-long trial began at Victoria station in June of that year. This cooling system relied on groundwater to absorb heat and did reduce the temperature at the station. The trial also discovered that though the system worked for Victoria Station, many other stations in the network would lack sufficient groundwater for the system to be effective.

In recent years, the answer to many heatwave woes have been bespoke solutions tailored to each underground station. As the network ages and the needs of its business and passengers change, this opens up new opportunities to install novel cooling systems. For example, in 2015 a disused lift shaft in St Paul’s Station was fitted with a fan that pulls in cool air from the street, and condensing pipes lining the shaft further cool the air as it descends to the platforms. A temperature drop of up to 7°C has been recorded since the system was fitted.

As it becomes possible to implement solutions on a case by case basis, the problem of overheating on the London Underground diminishes one station at a time. It is clear that this is one temperature problem that cannot be solved with a traditional air conditioning system. As has been demonstrated at St Paul’s and Victoria stations, with enough innovation and resourceful thinking, the problem of an unbearably hot underground system should someday be a distant memory.

Conditioned Environment supply, install and maintain commercial air conditioning for a variety of clients throughout Central London and beyond. With an expert team of engineers on hand, you can be sure that our units will provide efficient, safe and reliable service to you and your business. If you have any commercial air conditioning enquiries, don’t hesitate to contact our friendly team today.