- Almost all trains operated by SBB are air-conditioned, with 98% featuring a modern air conditioning system.
- The failure rate for these systems is just 0.24%, which means that out of a total of 9,100 air conditioners in use, only about 20 per day on average experience a malfunction.
- Several factors influence the air conditioning on a train, with the exterior temperature, the number of passengers and even the speed of the train all playing an important role.
- When the weather is hot, the air on the train is maintained at a temperature up to eight degrees cooler than the air outside in order to maximise passenger comfort.
- At SBB, a specialised team is responsible for ensuring that the air conditioning systems on trains operate reliably.
Trains
The ideal temperature on a train is a perennial “hot” topic. The fact is that achieving a comfortable onboard environment isn’t as simple as you might think. Temperature and ventilation cannot simply be controlled by pressing a button but depend on numerous other factors. Read on to learn more about air conditioning on trains.
One passenger freezes while another swelters. The “ideal” temperature on a train is a constant subject of debate. Especially when the air conditioning isn’t doing what it’s supposed to. Luckily, this happens far less frequently than many passengers might think. A look at the figures and how SBB’s climate control system operates dispels misconceptions and shows just how sophisticated air conditioning on trains actually is.
Today, around 9,100 air-conditioning units ensure that 98% of SBB’s passenger trains are air conditioned. Some older coaches, such as those used on the additional trains deployed during peak hours on the Zurich S-Bahn for example, and some coaches used for long-distance services have heating and year-round ventilation, but no cooling system. Trains without air conditioning are marked with a corresponding pictogram in the online timetable at sbb.ch and in the SBB Mobile app. This “no air conditioning” symbol will be used on a trial basis until the end of September.
One of the factors that determines the temperature on board a train is the exterior temperature, which is measured by temperature sensors on the outside of the vehicle. The number of sensors depends on the length of the train. For example, a six-coach train will have twelve external temperature sensors. The average measurement is used to determine the target interior temperature (which is also measured by temperature sensors in the passenger areas) and the supply of fresh air to the interior. An air-conditioned double-deck train is equipped with around 62 interior temperature sensors.
- In addition to the exterior temperature, numerous other factors have an impact on air conditioning:
- Whether the train is stationary or moving, and its speed
- Sunlight conditions
- Air humidity
- How full the train is
- The amount of heat emitted by the lighting and other electrical equipment on board
- How long the doors stay open when the train stops
- Whether the train is driving in the open or through a tunnel
The values for each of these factors, which, of course, change constantly during a journey, are fed into the automated air conditioning controllers to calculate the temperature inside the coaches.
The electronic controllers for the air conditioners are programmed to maintain the interior temperature three to ten degrees lower than the exterior temperature during hot weather. This complies with the European standards that railway companies in other countries also follow. However, if the air in the coach is perceived as too hot or too cold, train crews can manually increase or decrease the temperature by up to two degrees. SBB does not lower the temperature any further than this in order to avoid unpleasant temperature shocks for passengers entering and leaving the train and to limit energy consumption.
SBB logs an average of 600 air conditioning malfunctions per month involving heating, ventilation or cooling. This means that, on average, around 20 air conditioning units per day malfunction. With around 9,100 air conditioning units deployed fleetwide, this corresponds to a fault rate of just 0.24%.
The causes of the faults are as varied as the vehicles in the SBB fleet. They range from faulty sensors or defective air-conditioning units, cooling compressors, fans, heating elements or electrical switching elements to faulty controllers or bugs in the control
«The failure rate for air conditioners is 0.24 percent.»—
Even though the air-conditioning units work well most of the time, it is extremely uncomfortable to find yourself in a coach without air conditioning at the height of summer. The air conditioning experts at SBB do everything in their power to minimise the risk of this happening and make journeys as comfortable as possible for passengers. Their expertise is pooled in special “air conditioning focus teams” at the Olten and Bellinzona sites. The interdisciplinary and interdepartmental teams, comprising around 45 air conditioning experts from the fields of engineering, production and design in Olten and 4 in Bellinzona, keep passengers cool, calm and collected.
First of all, keep your cool. To ensure that faulty systems can be located and repaired as quickly as possible, we encourage passengers to report the fault directly using the contact form on
