Climate friendly mobile air conditioning for buses

a black and yellow bus of the BVG with inscription "CO2"Click to enlarge
Bus of Berlin’s public transport company (BVG) with CO2 air conditioning system
Source: Konvekta

Buses are eco-friendly means of transport, nevertheless their climate performance can be increased still further. Today’s mobile air conditioning systems in buses still use the refrigerant tetrafluoroethane (R134a), a greenhouse gas with a 1,430 times higher impact to the climate than carbon dioxide. There is a climate friendly alternative: Some city buses already use CO2 air conditioning systems.

Mobile air conditioning for buses

New coaches are normally air conditioned. Increasing numbers of city and intercity buses also got mobile air conditioning. From 1993 to 2011, the proportion of city buses with air conditioning rose from five to 68 percent, and for intercity buses to 84 percent. Mobile air conditioning systems in buses are not hermetically sealed, hence during  the bus’s lifetime considerably amounts of the refrigerant emit to the atmosphere and thus contribute to the greenhouse effect. On average,  mobile air conditioning systems in buses lose around 15 percent of their refrigerant annually. In 2010, some 100 tons of R134a refrigerant were released into the atmosphere by buses in Germany. This equates to emissions of 140,000 tons carbon dioxide per year. For the purpose of illustration, this is about the same amount as the the carbon dioxide tail pipe emissions of 90,000 fuel efficient compact cars.

Berlin city buses with CO2 mobile air conditioning

Seven Berlin city buses operated by Berliner Verkehrsbetriebe (BVG), Berlins’ public transport company, have been using air conditioners with natural CO2 refrigerant since July 2010. Being the world’s first company to operate a bus fleet equipped with climate friendly CO2 mobile air conditioning makes BVG an international pioneer in this domain. CO2 replaces the  the currently used refrigerant R134a, a greenhouse gas harmful for the climate but still allowed in buses.

the former UBA President Jochen Flasbarth making a speech, in the background yellow busses
Former UBA President Flasbarth at Berlin’s public transport company (BVG) press conference July 2010
Source: Dr. Wolfgang Plehn / UBA