Today's railway air-conditioning systems cool primarily with fluorinated refrigerants, which have had to be scaled back step by step since 2016 due to their climate-damaging effect. Air-assisted air-conditioning systems, so-called air-cycle systems, use compressed outside air for cooling, so they do not require any fluorinated refrigerants. It has now also been proven that these air conditioning systems, which have been operating in trains for some time, are an environmentally friendly and economical solution to the refrigerant problem. For this purpose, the data from a two-year field data measurement in an Intercity Express were evaluated with regard to energy consumption and the life cycle costs of these air conditioners were determined. Air-cycle systems have an average annual cooling energy requirement of up to 28% less than conventional R134a systems.