Puffing and sweating in a scorching hot coach: that's a thing of the past. All passengers now enjoy a comfortable ambient temperature. However, stricter environmental requirements are forcing manufacturers of cooling systems to develop new technologies that focus on eliminating harmful gases. At Busworld German manufacturer Spheros is presenting an eco-friendly air conditioning system based on propane gas and CO2.
Spheros will present its REVO-E 290 unit for the first time at Busworld 2025. This is a ready-to-use solution for installing air conditioning that uses the coolant R290. R290 is the CO2 coolant that offers optimal results compared to the harmful gases that are already banned in passenger cars. However, no guidelines exist yet for cooling systems in buses and coaches. The air conditioning unit weighs approximately 360 kilograms, consists of a single unit and is installed on the roof of the coach.
“We offer units with two different gases. CO2 offers the best results for vehicles operating in extremely cold regions. This product works under high pressure. In warm regions, CO2 is less energy-efficient and requires more power, which reduces the vehicle's driving range, “says Frank Färber, sales director at Spheros.
Propane
Spheros can also operate its cooling system with propane gas. Like CO2, propane is a natural coolant with a negligible harmful effect. Unlike CO2, propane is more suitable for use in warm areas. However, fire safety measures for propane require additional provisions. Propane is mainly used in heat pumps for homes.
“Thanks to the different properties of our coolants, we can offer units for both cool and warm regions around the world. For electric city buses, switching to environmentally friendly coolants is technically possible and is already being implemented. Currently, these buses are still equipped with harmful coolants, “says the sales director.
For coaches equipped with diesel engines, the transition is more complex. Possible solutions include coolants with a better eco-score, but they are far from matching the advantages of CO2 and propane. Spheros has developed a system with a generator that produces extra power for the air conditioning and supplies the unit.
‘‘We realise that diesel coaches will continue to be used for long-distance travel for at least another twenty years. For those vehicles, we need to offer adapted, environmentally friendly cooling systems, “says Frank Färber.
In addition to climate control for the interior, Spheros' REV0 unit can also cool the batteries of an electric vehicle and provide extra fresh air in the driver's cab.