Introducing Air Conditioning to the London Underground

It’s not that easy to install air conditioning on London Underground trains, but it can be done, as Anthony O’Connor, factory manager at LH-plc, explains

The world’s first underground railway system – London Underground – has a long and eventful history. It began with the grand opening in 1863 of the Metropolitan Line between Paddington and Farringdon, which served just six intermediate stations. 

Since then, the capital’s underground network, colloquially known as the Tube, has grown to 272 stations and 11 lines stretching deep into London’s suburbs and beyond.

But the development of London Underground has been punctuated by a series of challenges (including the geography, existing infrastructure, and the disruption caused during construction) as it has expanded and become ever more popular. And the design of the transport itself proved tricky as the earliest tube trains ran on steam with all the attendant problems this led to in a confined underground space.

Many seemingly intractable problems have been solved with advances in technology, but there is one relatively new challenge that has proven particularly hard top crack – how to deal with the build-up of excessive heat in the tube system, especially due to the impact of global warming (or, more accurately, global heating).

The Heat Challenge in London Underground

Although it has not impacted the system much so far this year (due to unseasonably cool temperatures), the intensity of heat in parts of the London Underground can become very uncomfortable if not positively unbearable during heatwaves because of the system’s deep and poorly ventilated tube tunnels. 

Temperatures as high as a blistering 47°C have been recorded on some parts of the tube system and even the average temperature in summer months is typically more than 30°C.

Tube Lines Without Air Conditioning

Some tube lines (including the Circle, Hammersmith & City, District, and Metropolitan) do have air conditioning. However, the following do not currently employ any cooling – Central, Bakerloo, Jubilee, Victoria, Piccadilly, Waterloo & City, and Northern.

The problem is that the oldest tunnels built in the Victorian era are just about big enough for the trains themselves, making it next to impossible to make room to add air conditioning equipment to them.

London Underground

Upcoming Solutions and Upgrades

However, there is, to coin a phrase, some light at the end of the tunnel. New train designs mean that the Piccadilly line should be enjoying air conditioning next year, while the Central, Bakerloo and Waterloo & City lines are all due upgrades in the near future, according to the well-respected Engineering & Technology magazine from the Institution of Engineering and Technology.

It says: “Thanks to new train designs, the engineering team working on the Piccadilly Line refresh are confident that passengers will finally be able to ride in comfort during the summer months beginning in 2025.”

Simon Ford, programme delivery engineer for the Piccadilly Line Upgrade, is quoted as saying: “We have managed to work with Siemens to end up with a train which has both open wide gangways going between the carriages and has saloon cooling.”

Specifications of the New Fleet

According to Transport for London (TfL), 94 trains will make up the new fleet entering service next year.

A TfL spokesperson said: “The system uses vapour-compression refrigeration with temperature control but without the humidity control that is typically provided in buildings. Strictly speaking, this is an ‘air cooling’ system. However, this type of system is widely referred to as an air conditioning system when referring to trains and other mobile applications such as cars.”

The Urgent Need for Air Conditioning

In whichever terms it is described, the cooling system is arriving not a moment too soon. TfL says the average temperatures for the tube lines in July 2020 were nearly 30°C on the Bakerloo and Central lines leading to extremely uncomfortable passengers. 

But it is not only passengers who suffer. One driver described the conditions as being “like an absolute steam room in the driving cab during the summer”. Another said: “Temperature often exceeds 40°C and, on many shifts, I’m left feeling physically sick due to the heat.”

Partnering with Experts for Optimal Solutions

The best way to understand what is going on with railway air conditioning is to join forces with a trusted, well-established partner with experienced and approachable staff.

One such is LH-plc, which provides specialist servicing and maintenance to ensure railway air conditioning systems perform well and deliver comfortable conditions for drivers and passengers. The company carries out work on behalf of many of the major UK rail carriers as well as Transport for London (TFL). 

Lodon TUbe

LH-plc’s Railway Expertise and Services

LH-plc’s cutting-edge railway air conditioning refurbishment and servicing centre in Wimbledon, south-west London combines state-of-the-art facilities with well-qualified and experienced engineers to offer an exceptional service that is both reliable and offers premier quality.

The company’s skilled team of specialist engineers boasts more than 30 years’ experience in this specialist sector, having developed extensive knowledge and unique engineering skills focused on the requirements of railway air conditioning systems.

LH-plc’s services include regular servicing and maintenance to ensure railway air conditioning systems continue to perform well and deliver comfortable conditions for passengers.

Meanwhile, first-rate engineering and assessment facilities ensure that railway air conditioning systems sent to it for refurbishment are processed and returned to service in the best possible working condition.

Once systems have been serviced or refurbished, LH-plc conducts a monitored full load test to ensure the unit performs to specification and thus to offer peace of mind. The company is registered and accredited by RISQS (the Railway Industry Supplier Qualification Scheme), which gives customers confidence that they can find the right supplier, with the right capabilities, at the right time.

For more information, visit here. Alternatively, call LH-plc on 020 8971 4186 or email us at