The air conditioning of trains is a controversial issue which, up until now, has never really focused on aspects such as the energy efficiency of the systems installed or the type of refrigerant used. Priority has always been given to system size, weight, safety and cost.
Due to worsening climate change and the introduction of new anti-pollution legislation, even train manufacturers have had to adopt greener air conditioning systems. Although this presents a complex challenge, further aggravated by the absence of long term alternatives (essential to ensure a longer operational life for trains), solutions are being sought.
How HVAC trends in the railway sector have changed
Restrictions on certain refrigerants imposed by the European Green Deal, are causing significant problems for the railway sector. Trains are usually built to be operational for at least thirty years and this includes the air conditioning systems inside.
If, however, the refrigerant used in these systems is banned and withdrawn, it is understandable that finding alternatives to replace it can be difficult. The change in trends relating to air conditioning systems for trains began with the revision of the F-Gas regulations, making it necessary to re-think the criteria used when choosing HVAC systems.
It is no longer sufficient that these systems occupy a small space or that they are lightweight and cost-effective; now they must be built according to long-term objectives and be able to function using low GWP refrigerants (to reduce the risk of being unexpectedly withdrawn from the market as much as possible).
It is not at all easy to find the right compromise, especially if we consider that not all trains operate in the same meteorological conditions. This implies the development of ad hoc solutions, in order to achieve the best results at the best price.
A closer look at the available alternatives
In a short article (accessible via this link), the well-known HVAC portal, Zerosottozero reported details of an interesting analysis carried out by certain multinationals, specialised in the manufacture of rolling stock. The document includes an examination of the possible alternatives among current trends in air conditioning for trains.
The conclusions which emerged are indicative of a rather complex and unstable situation, which is worrying producers considerably. Below is a summary of the key points which formed the focus of the discussion:
- It was confirmed that the F-Gas regulations have had an enormous impact on the railway sector;
- Today, there are many widely-used synthetic refrigerants which could represent a long-term risk, due to their increased environmental impact;
- There are still no alternatives available which use natural refrigerants for air conditioning on trains. Several solutions are currently being explored, including: CO2 and air (even though the weight-efficiency ratio is not optimal), hydrocarbons (which have the same flammability level as other refrigerants currently in use) and more specific alternatives that will vary according to future technologies and the requirements of individual operators;
- The use of certain inflammable substances is also being considered, such as hydrogen, HFO and hydrocarbons (currently the most favoured, thanks to the many applications they have had in a commercial context in recent years).
As is apparent from the data contained in the report, there are not many viable alternatives available and none of them offers the kind of long term solutions which air conditioning systems on trains really need. All the options are being explored however, with hopes being placed in future technologies and, in particular, in the next generation of refrigerants, currently still in the development phase.
Translated by Joanne Beckwith