All About Series | February 27, 2024
All About Operating Electric School Buses in Cold Weather

Electric school buses are proven to operate effectively in cold weather with some adjustments. Here’s what to know.

A school bus drives in the snow.

As electric school buses hit the road nationwide, it’s important for school districts and school transportation providers to prepare for how these clean-running buses will perform in different climates. The good news? Electric school buses are tested and ready, with advanced batteries and operational systems that perform well in all weather, from the heat of Arizona to the winter cold of Salt Lake City.

Here’s what to know about electric school buses and cold weather.

The evidence from cold weather communities nationwide is promising: electric school buses are performing well in extreme cold, and they’re ready to deliver clean rides to students in winter climates today.

Electric school buses successfully operate in cold climates across North America

Electric school buses are successfully delivering clean rides for students in areas that consistently face extreme cold weather including Michigan, Utah, and Canada. That’s because today’s electric school buses — equipped with powerful batteries and thermal management systems — are designed to handle the tough cold and can be deployed successfully with proper planning, including route selection, charging scheduling and pre-heating.

Electric school bus batteries lose a percentage of their capacity in extreme cold weather, though the exact percentage varies based on temperature, terrain, heating source and other factors. So it’s crucial to plan routes and charging schedules with the winter months in mind, ensuring that buses have plenty of range to cover all necessary routes.

Already, school districts in cold weather climates are seeing great results when deploying electric school buses throughout the winter months:

  • Garretson School District in South Dakota found that their three electric school buses are running strong in the winter in below-zero temperatures. The buses can travel up to 125 miles in optimal conditions and Garretson’s longest route is 47 miles, so the range lost in cold temperatures hasn’t been a concern when transporting students to and from school.
  • Morris Area Schools in Minnesota are also happy with their electric school bus results. The buses have operated through several winters and while they lose about 10-15% of their battery capacity, including when temperatures drop below zero degrees Fahrenheit, they have been able to keep routes going. The superintendent is pleased with fuel savings, noise reductions and alignment with a community-wide focus on clean energy.
  • West Grand County School District in Colorado have operated an electric school bus since 2020 despite being located in “one of the coldest places in the state.” Morning winter temperatures range between minus 30 degrees and 5 degrees Fahrenheit. The director of transportation says the electric school bus performs extremely well, and that it also is the best bus in their fleet with much lower operating costs than their diesel-burning buses.

These on-the-ground stories are backed up by real-world performance data collected over the past few years. Barre Unified Union School District (BUUSD) in Barre, Vermont participated in a one-year evaluation of their two Type C electric school buses by the Vermont Department of Environmental Conservation (DEC). Barre, located in central Vermont among the Green Mountains, has an average low temperature in the winter of 12 degrees Fahrenheit and an average monthly snowfall of 20 inches. Approximately 60% of the bus routes used by the electric school buses in the pilot were considered rural, with elevation changes up to 600 feet.

Despite harsh mountain winters, DEC found that the electric school buses in Barre performed well on daily routes. Barre’s electric school buses retained enough battery range, achieved emissions reductions when compared to their diesel-burning counterparts, and realized operational savings over the winter months. The report found that the average, annual real-world range between charges of the two electric school buses was 74 and 78 miles, a 25% reduction in range yet well above their average daily trip totals of 37 and 32 miles.

A graphic showing the daily range and winter range of electric school buses in BUUUSD in Vermont. The winter range is slightly less than the daily range, but is much more than the daily route length.

Emissions reductions were considerable for Barre electric school buses when compared to both diesel-burning buses put out of service and new diesel-burning buses. The following tables present the well-to-wheel emissions reductions seen for Barre’s electric school buses compared to both scenarios. The differences in NOx and PM reductions observed between the two replacement options can be attributed to the Environmental Protection Agency’s stricter emission standards for NOx on new diesel-burning buses, reiterating the need to prioritize replacing the oldest diesel-burning buses in school fleets.

The operational savings of the electric school buses when compared to their diesel-burning counterparts were also seen as an advantage. Total dollar per mile savings were $0.24 to $0.25 in Barre, as detailed in the table below.

This finding is reinforced through similar school district experiences operating their buses in cold weather.

 The school bus fleet manager at Havre School District in Montana, where the temperature reached minus 44 degrees Fahrenheit this past January, found that their electric school bus’s per-mile cost is one-half or one-quarter of the cost for a gas- or diesel-burning school bus. In West Grand County School District in Colorado, the director of transportation reported their electric school bus averages 26 cents per mile and the diesel-burning buses average 58 cents per mile, which they noted does not include oil changes, filter, lubes and other maintenance costs that diesel-burning buses incur.

The evidence from cold weather communities nationwide is promising: electric school buses are performing well in extreme cold, and they’re ready to deliver clean rides to students in winter climates today.

Garretson School District in South Dakota found that their three electric school buses are running strong in the winter in below-zero temperatures.

Electric school buses perform better than diesel-burning buses in snowy conditions

Unlike a diesel-burning bus with weight concentrated in the front, electric school buses’ battery weight is more evenly distributed between the front and rear wheels, improving driving ability in the snow. School bus drivers across the country have shared their experiences with improved stability.

Tom Godbee, a veteran bus driver in South Dakota said his electric school bus is a safer mode of transportation in the winter: “I’ve driven a diesel bus, a propane bus, and now an electrical bus… In the other buses, all the weight was in the front. [Now,] I’ve got more control, and better traction, and they handle better.”

In Virginia’s Appalachian Mountains, Carroll County public schools found during the Arctic cold of the winter 2024 that the weight of the batteries has given “a more solid feel” to the vehicle on the road compared to diesel-burning buses because there is no movement of gallons of fuel moving from side-to-side.

And in Michigan, Three Rivers Community Schools reports that their electric school buses often outperform their diesel-burning counterparts in winter weather. Specifically, they found that electric school buses’ overall heavier weight and the fact that their weight is centered between the axles have made them less likely to fishtail in snowy conditions.

Three Rivers Community Schools reports that their electric school buses often outperform their diesel-burning counterparts in winter weather.

Electric school buses are equipped with technology to address the impacts from cold weather on the battery

Cold weather does reduce electric school buses' range by slowing reactions within the battery and because more energy is needed to maintain the cabin temperature and the temperature of the batteries themselves. When the ambient temperature is warmer, an electric school bus utilizes all its energy to exclusively propel the vehicle and therefore achieve peak driving ranges. The impacts from cold weather on range can vary depending on several factors like the bus’s route terrain and heating system; however, electric school buses are designed with technology to minimize these impacts.

First, electric school buses are equipped with battery thermal management systems that maintain an internal temperature range for safe battery function. The battery thermal management system draws energy from the batteries both during operation and while idling or charging, which helps the battery operate at its optimal temperature in all conditions. This pulls some power from the battery and helps ensure that the bus can safely and effectively perform even in extreme cold.

Also, electric school buses can recover energy during colder temperatures that would otherwise be lost through regenerative breaking. Regenerative braking occurs on downhill rides or during slow stopping like at stop signs, traffic lights and bus stops, or while in traffic. Specifically, battery power turns the motor — but while braking, the motor can be reversed and recharges the battery, thus extending the range of the bus, which proves especially beneficial during cold weather. Salt Lake City School District in Utah found that they can get around 16% additional range from regenerative braking. It also has an added benefit of lower wear and tear on braking systems.

Heated driver seats also allow electric school buses to conserve battery power since they require less energy than heating the entire bus cabin. With a heated driver seat, a driver can turn off or lower cabin heat when students exit the bus, extending the bus’s range.

Some school districts in cold weather climates have opted for auxiliary, fossil fuel heaters on their electric school buses to heat their cabins and save battery power. These auxiliary heaters can negatively impact emissions reductions and operational savings from fuel costs, but help preserve battery life in cold weather. In Vermont, the DEC found that the diesel auxiliary heaters used about 80 gallons of diesel and cost approximately $0.07/mile. Since the buses traveled around 35 miles per day, this amounted to approximately $12 per week in diesel fuel costs. Morris Area Schools in Minnesota have diesel-powered auxiliary heaters on their electric school buses, but the district’s senior vice president of operations says that they haven’t been used much as the buses stay warm running on battery power alone.

Despite harsh mountain winters, Vermont's Department of Environmental Conservation found that the electric school buses in Barre performed well on daily routes.

Training and preparation can help electric school buses operate even more efficiently in colder temperatures

Routine maintenance and care can optimize an electric school bus’s performance in the cold. The federal Joint Office of Energy and Transportation recommends several approaches that include:

  1. Preconditioning the bus. Preconditioning refers to warming up the battery and cabin to its optimal temperature before starting the bus’s routine trip. Heating up the electric school bus while it is plugged into the charger uses power from the grid and reserves the battery power for the route.
  2. Storing the bus indoors overnight. Storing the bus indoors has several benefits that improve overall operation. Indoor storage reduces the power needed by the battery thermal management system to regulate the battery temperature, improves heater efficiency on the route, and decreases the time and power needed for preconditioning in the morning. If indoor storage is not feasible, another option is to store the buses under outdoor canopies, especially in areas with frequent winter precipitation. This can help reduce snow and ice on the bus, as well as snowbanks around chargers. These options can be considered when bus and charging infrastructure are being acquired and designed.
  3. Charging at mid-day or end-of-day. When it’s cold outside, charging an electric school bus after it returns from its route can avoid any extra power needed for the battery thermal management system since the battery will already be at an optimal temperature. This will allow for a faster charge that goes directly to replenishing the bus’s range.
  4. Planning the routes. New technologies should be evaluated for their performance. School districts can consider driving electric school buses on the shortest, least demanding routes during its first winter to understand its effective range in cold weather. This analysis will aid in understanding cost savings and planning mid-day charging schedules. While technical feasibility is the primary consideration in the decision of which routes to electrify first, there is also the potential for these initial deployments to lessen the disproportionate levels of harmful air pollution faced by communities that have been historically marginalized and by low-income communities. This resource discusses how school districts can include equity when choosing where to deploy electric school buses first.
  5. Understanding charger weatherproof ratings. The National Electrical Manufacturer Association (NEMA) uses a standard rating system that defines the types of environments in which a charger's enclosure can be used. This can help districts understand an enclosure's ability to withstand certain environmental conditions like extreme cold, snow, and ice.
  6. Training bus drivers. Training for electric school bus drivers should be provided by the bus manufacturer, dealer and/or the state pupil transportation association. It is beneficial to an electric school bus’s operation in cold weather that drivers know how to properly precondition the battery, heat the cabin and charge the vehicle.

Students in cold weather climates and on longer routes should not be left behind as school districts transition to clean rides.

Every student deserves a clean ride to school, no matter their location

Electric school buses offer a safe, clean way to bring students to and from school – and the benefits of electric school buses should not be denied to children living in colder climates. With strong evidence that electric school buses perform well in cold weather, school districts have the opportunity to provide clean, tailpipe-emissions-free rides to their students no matter their location.

And while shorter routes can be easier to transition to electric school buses when there are concerns about range, particularly in cold weather, it’s important to remember that students with long trips to school stand to benefit most from electric school buses due to reduced exposure to tailpipe emissions.

Rural students, for example, face long bus rides that extend their school day, increasing their exposure to toxic school bus exhaust along the way. Data also shows that Black students tend to have longer rides to school — on average 45 minutes to an hour — than their white and Hispanic counterparts. And students with disabilities travel longer distances on their school bus than other students.

That’s why it’s important to consider equity when planning which routes to electrify first. While cold weather impacts range, students in cold weather climates and on longer routes should not be left behind as school districts transition to clean rides. By sharing electric school bus experiences in cold weather, efficiency data and training best practices, school bus fleets can ensure the transition to electric school buses happens equitably across varying climates and for all students.

Learn more about operating electric school buses in cold weather