eco2jet – Evaluation and demonstration of an energy-efficient, cost-efficient and eco-friendly HVAC system using R744 through the ÖBB railjet


HVAC systems like:

  • heating,
  • ventilation, 
  • air conditioning,

are a major energy consumer and producer of greenhouse gas emissions in railway applications. These emissions result mainly from indirect CO2 emissions caused by the operation of an heating and air conditioning system. These using a lot of electrical and mechanical energy to fulfill the comfort requirements of more than 100 passengers in one train. Typical HVAC systems account for up to 30% of total energy consumption of the passenger transport by rail. They are the largest energy consumer after the traction system.

In addition to the improved cooling functionality, the integration of an energy-saving heat pump for heating operation would bring huge benefits. The railway air conditioning systems fulfilling both system approaches are still at the beginning of their development and offer therefore a great potential in the field of energy efficiency. Furthermore, the choice of an alternative refrigerant such as R744 (CO2) significantly reduces the need for conventional refrigerants. Consequently, it reduces the emission of greenhouse gas and complies with the Austrian and European restrictions regarding refrigerants.

The project consortium of eco2jet has decided to develop:

  • a system-wide optimized,
  • environmentally friendly air conditioning

based on R744.  Including heat pump function incl. new energy-efficient, cost-effective and production-optimized components. This innovative air condition will be demonstrated and evaluated in regular operation in a train of the Austrian railway operator ÖBB.


Compared to conventional air conditioning systems, the eco2jet HVAC system is targeting two main goals:

  • increase in energy efficiency by at least 30% in real rail transport including a innovative heat pump function,
  • reduce greenhouse gas CO2 from energy production by 30%

The project results can be transferred to non-rail vehicles such as trucks, cars, agriculture machines or airplanes. Which have similar power requirements like eco2jet. So eco2jet will have a sustainable effect going far beyond the primary context of this project.

The industry-driven consortium of eco2jet includes relevant, internationally active partners that cover the full value chain for :

  • the development,
  • production,
  • integration and demonstration / operation of the HVAC system,

in a real train.

It consists of operators, system integrators, Tier X-suppliers, engineering service providers and research institutions.

In addition to the sustainable safeguarding of the Austrian competitiveness in the railway sector including an appropriate market penetration in Austria. There is also the opportunity for rapid penetration of the European rail market through the innovative HVAC solution developed in eco2jet .