Researchers found equipping the bus with a diesel-powered cabin heater helps prevent too much drain on battery range

An argument against electric vehicles has always been a diminished operating capacity in cold, harsh winters. But a recent year-long study conducted in Edmonton shows electric school buses (ESB) are able to cope well with extreme weather.

Three organizations — Pollution Probe, Mobility Futures Lab and RFS Energy — cooperated on the study titled, Electric School Bus Demonstration: An Edmonton Case Study.

Between April 2024 and April 2025, the study tracked the performance of a 77-passenger Lion Electric Type C ESB equipped with a 126-kWh battery and run by Rental Bus Lines, an operator of school buses in Edmonton.

The bus made 298 trips (lasting at least one-hour in duration).

Most of those involved the typical, twice per day, 55-km round trip from the bus depot to two schools, although there were times when the bus was used for extra curricular trips or trips during the summer vacation period.

Over the course of its usage, bus charge range varied from 111 km to 228 km from a single charge. Even at its lowest cold weather performance, the Lion bus’s range was double that needed to cover the distance of the usual school route.

Managing cold weather conditions

The Edmonton study was conducted, at least in part, as a comparison to a study conducted in Calgary in 2023 featuring a bus that was fully electric.

“In that [Calgary] study, energy intensity rose by approximately 85 per cent — from 0.7 to 1.3 kWh/km — as temperatures dropped from 20°C to -10°C. The more moderate increase observed in the current study highlights the benefits of using an auxiliary diesel heater to preserve efficiency in cold weather.”

In the just-released Edmonton study, the bus, while having an electric propulsion system, was also equipped with a diesel-based cabin heater.  

“During the core school months, [electric school bus] energy intensity increased moderately — by approximately 12 per cent — between fall and winter (0.73 to 0.82 kWh/km),” reads the report.

“Comparing the best and worst observed days, energy use increased by 58 per cent — from 0.62 to 0.98 kWh/km — as temperatures dropped to -30°C.”

Meanwhile, the bus’s regenerative braking system “recovered an average of 20 per cent of energy across all trips, and charging remained stable, with only a minor performance dip (approximately 10 per cent) in extreme cold.”

The bus was plugged in each time it returned to the depot.

The average state of charge prior to regeneration was 64 per cent, and the bus typically took between two and three hours to reach a fully charged state. According to the report, “The charger delivered consistent power output across all sessions, with only a slight decrease — approximately 10 per cent — observed during extreme cold conditions (-20°C to -30°C).”

Health and wellness

In addition to the performance data collection, the study considered the public health effects of switching to ESBs by simulating emissions output for three types of buses: a diesel bus with a diesel heater, an electric bus with a diesel heater and an electric bus with an electric heater.

Researchers determined that when it came to total annual GHG emissions, they would drop from 12,526 kg CO2e for the diesel bus to 8,981 kg CO2e for the electric bus with a diesel heater (which is a reduction of 28 per cent) and to 7,824 kg CO2e for the electric bus with an electric heater, representing a 38 per cent reduction.

Similarly, they calculated that nitrogen oxide emissions would also be reduced by moving away from fully diesel buses which emit 12.6 kg of NOx annually versus 7.5 kg for the electric bus with diesel heating (a 40 per cent reduction) and 6.4 kg for the electric bus with electric heating (resulting in a 49 per cent reduction).

Over the course of the study, Rental Bus Lines called the Lion Type C the most reliable bus in its fleet. It spent five weeks off the road: three after a charger wiring failure that the bus company was able to repair itself and two weeks during which the bus had to be sent to the dealership after the ESB was struck by lightning.

ESB safety

Rental Bus Lines put its first ESB on the road in 2018, and has experience maintaining and servicing the electric vehicles in Alberta.

They haven’t reported any significant issues.

However, the question of servicing ESBs in Quebec has recently become an issue after a LionC electric bus caught fire in Montreal earlier this month.

The fire was determined to be due to the bus’s heating system, not its battery.

Following the incident, the province’s Ministry of Education decided to pull 1,200 LionCs off the road and subject them to inspections.

Other jurisdictions followed suit, including London, Ont., and Prince Edward Island. The latter declared their Lion electric buses “safe” after inspections. Mostbuses have since returned to the road.

Transport Canada is investigating the September 9 fire in Montreal in addition to two others that happened in the last 12 months in Hunstville Ont., and Ascot Corner, Que.