Cold-Climate Cities Could Cut Electric Bus Costs by Charging More Slowly
Electric buses are often presented as a straightforward route to cleaner urban transportation, but a new McGill University study suggests that the way cities charge those vehicles may determine whether large-scale electrification succeeds. Researchers say cold-climate cities could reduce pressure on electrical grids and lower operating costs by using more chargers at lower power levels, allowing buses to recharge gradually instead of relying primarily on high-speed charging.
The recommendation challenges the intuitive assumption that faster charging is always better. High-power chargers can restore a bus’s battery within minutes, making them attractive to transit agencies trying to keep vehicles on the road. However, these systems can create sharp spikes in electricity demand, requiring costly grid upgrades and potentially increasing energy expenses. Slow charging takes longer, but distributes consumption over a wider period and can make the overall system easier and cheaper to operate.
The issue becomes especially urgent in winter. Electric buses consume more energy in low temperatures because batteries operate less efficiently and because additional power is needed to heat passenger cabins and maintain comfortable conditions. According to the McGill researchers, winter conditions increased the simulated network’s energy demand by approximately 30 per cent. That increase can reduce driving range, complicate schedules and force buses to recharge more frequently.
“Anyone can operate an electric bus fleet, but minimizing operating and environmental costs should be a concern, because everyone is paying for these systems,” said Luis Miranda-Moreno, an associate professor in McGill’s Department of Civil Engineering. “We are trying to help bring awareness and build tools that reduce costs.” The researchers argue that careful planning, rather than simply purchasing more powerful vehicles or chargers, will be essential for cities seeking to eliminate diesel buses.
To examine the problem, the team built a digital model of Quebec City’s electric bus network and its supporting infrastructure. The model used an agent-based simulation, a computational approach that represents individual actors—in this case buses, passengers and elements of the traffic system—and allows them to interact over time. This made it possible to estimate how changes in passenger demand, traffic conditions, weather and charging availability could influence energy consumption across an entire municipal transit system.
The researchers then combined the simulation with an optimization tool. Instead of testing only one fixed fleet design, the tool evaluated different combinations of bus numbers, charger locations, charging schedules and battery operating thresholds. A battery threshold can determine how low a bus’s charge is allowed to fall before it is sent for charging, or how much reserve energy must be maintained to protect service reliability. These decisions can affect both the number of buses required and the amount of electrical capacity a transit agency must secure.
The model compared fast-charging and slow-charging strategies under different weather conditions. Fast charging provided more energy in a shorter period, but demanded greater instantaneous power from the grid. Slow charging required buses to remain connected for longer periods, yet it reduced peak demand. The optimization results indicated that a larger fleet, combined with more charging points operating at lower power, could consume less grid capacity and prove more cost-effective than a smaller fleet dependent on rapid charging.
A larger fleet may sound like an expensive solution, but the researchers say the calculation must include the full cost of infrastructure and energy. A transit system with fewer buses may require extremely powerful chargers to keep vehicles in continuous service, creating expensive peaks in electricity demand and requiring substantial electrical upgrades. Adding buses and chargers can spread operations more evenly, allowing vehicles to charge during longer idle periods, including overnight or between scheduled runs.
The findings could be particularly important as cities across Canada and other northern regions plan to replace diesel fleets. Transit agencies must balance emissions reductions with reliability, passenger demand, winter weather and limited budgets. “In Canada, there is no one-size-fits-all approach to fleet electrification,” said Jônatas Augusto Manzolli, the study’s lead researcher and a postdoctoral fellow in McGill’s Department of Civil Engineering. He added that this type of analysis can help cities align winter operations, charging requirements and grid capacity before investing in infrastructure.
The study, published in Applied Energy, is described by the researchers as the first to model electric bus operations at the municipal level under winter conditions. Its importance extends beyond climate resilience: transit agencies frequently operate with financial deficits, so reducing energy and infrastructure costs could influence how quickly they can electrify. The team plans to apply similar methods to transit systems in Montreal and Ottawa. The researchers say their framework could ultimately help cities design electric bus networks that remain reliable in extreme weather while reducing diesel dependence, grid stress and the environmental cost of urban transportation.
Subject of Research: Computational modeling of electric bus operations, charging infrastructure and energy use in cold-climate cities
Article Title: Planning resilient electric bus operations in cold regions: An agent-based simulation–optimization framework
Web References: https://doi.org/10.1016/j.apenergy.2026.127735; Luis Miranda-Moreno, McGill University; Jônatas Augusto Manzolli
References: Manzolli, J. A., D’Apice, A. V., Miranda-Moreno, L. et al. “Planning resilient electric bus operations in cold regions: An agent-based simulation–optimization framework.” Applied Energy. DOI: 10.1016/j.apenergy.2026.127735. Published 15 June 2026.
Keywords
Electric buses, cold climates, winter transportation, slow charging, fast charging, electric vehicle infrastructure, grid capacity, battery efficiency, transportation engineering, civil engineering, sustainable transit, Quebec City, fleet electrification
