Document Type


Publication Date


Research Center

Energy Policy Center


This report is an update to a 2019 evaluation of the effects of changes in ambient temperature on the fuel efficiency and range of zero emission buses (ZEBs). (The 2019 evaluation is available at The report relies on data that was made available from transit agencies that have deployed hydrogen fuel cell electric, battery electric, compressed natural gas (CNG), and diesel buses. Additional control variables were included in this update to isolate the fuel efficiency effects associated with temperature variation. This analysis reinforces findings from the 2019 report showing that fuel economy and range for electric drive buses vary significantly with changes in outdoor temperature. However, relative decreases in fuel economy for ZEBs at both extremely low and high outdoor temperatures were smaller for this update compared to the 2019 report. Additionally, ZEBs did not exhibit greater fuel efficiency uncertainty at temperature extremes compared to fossil fuel-based vehicles. The results suggest that transit agencies deploying ZEBs have made operational improvements to increase the efficiency of these vehicles.