The electrification of public transportation in Poland is now an integral part of urban mobility policy and emission reduction strategies. Electric bus procurement programs (EBP) typically focus on two budget items: battery capacity and charging infrastructure.
In operational practice, however, it is the thermal strategy (battery and cabin temperature management and the integration of these functions with charging) that determines whether a project “works” only on paper or is economically viable in operation.
Thermal management directly affects energy consumption, range, charging throughput, battery degradation rate, vehicle availability, and final TCO. These six channels form a network of interdependencies in which temperature variability is the most costly factor—it creates the need for fleet reserves, additional grid capacity, or more frequent battery replacements. The analysis below breaks down the mechanisms by which thermal management impacts each of these channels and offers practical design and operational recommendations.
Mechanism: The cabin HVAC and auxiliary circuits compete with the traction system for battery power. Additionally, temperature affects internal battery losses (resistive, BMS control) and the efficiency of onboard systems.
Data: Under extreme conditions, HVAC’s share of total energy consumption can reach up to 24%, and additional losses related to temperature and the battery can account for approximately 12% of total consumption.
Economic consequences: As the HVAC share increases by several percentage points, the value of usable energy per kilometer (kWh/km) rises proportionally, which increases direct fuel (energy) costs and affects charging windows (shifting toward more expensive rates). For the operator, this means higher OPEX and increased sensitivity to tariff structures.
Recommendation: Design systems with a heat pump adapted to the local temperature profile (higher COP at low temperatures), use preconditioning during charging, and implement strict cabin zoning and door seal optimization. In cost models, account for seasonal variance in kWh/km.
Mechanism: Temperature ranges directly affect usable battery capacity and energy efficiency per km. Reduced range necessitates shorter routes, additional recharging, or an increase in the number of vehicles.
Data: Operational data indicates a ~30% decrease in range in winter compared to summer.
Economic consequences: A ~30% reduction in range forces either an expansion of the fleet (CAPEX) or changes to schedules and crew assignments (operating costs and service quality). The unit cost of transport increases, while the predictability of schedule fulfillment decreases.
Recommendation: Fleet planning should account for range during the “worst week” of the year, not just the average value. In the tender specifications, require a kWh/km vs. temperature curve based on a real-world cycle (with passengers and frequent door openings). Consider larger batteries only if economically justified; preconditioning and heat pump strategies are often better.
Mechanism: The battery has temperature-dependent power acceptance limits: at low temperatures, preheating or limiting the C-rate is necessary, which extends charging time. High temperatures, in turn, may require battery cooling during charging.
Data: Charging time in winter may increase by 50–100% compared to reference conditions.
Economic implications: Extended charging times reduce the depot’s “energy throughput”—more charging stations and higher connection capacity are needed. This generates CAPEX (stations, connections) and may shift charging into more expensive tariff windows, increasing OPEX.
Recommendation: Design infrastructure with a time and connection capacity margin based on seasonal data; use preconditioning during charging to shift thermal preparation to periods of cheaper energy. In tenders, require OEMs to specify maximum power at various temperatures and the time required to reach full charging power.
Mechanism: Thermal profile (exposure to high temperatures, frequent charging at low temperatures with high C-rates) accelerates degradation processes (including lithium plating and accelerated capacity loss).
Data: Thermal losses and operations outside the optimal window can add significant energy consumption (up to 12%) and accelerate degradation, which shortens battery service life within scheduling requirements.
Economic consequences: Accelerated degradation leads to earlier battery replacements or the need to increase the fleet size, which increases CAPEX and total life-cycle cost. Inappropriate charging policies can shift costs to the operator in the form of additional replacements or loss of service life.
Recommendation: Require suppliers to provide transparent degradation data under defined temperature and charging profiles; integrate the BMS with energy management to limit aggressive charging profiles in cold weather. Invest in battery thermal management systems (BTMS) with the capability for active temperature control before and after charging.
Mechanism: Inappropriate thermal management results in power derating, unexpected route deviations, extended charging times, and additional preparatory steps (de-icing, preconditioning).
Data: In cold climates, there is a significant increase in traction limitation incidents and extended downtime; the share of idle energy consumption in hot weather reaches 5–15% of daily consumption.
Economic consequences: Downtime generates dual costs: direct maintenance costs and loss of transport capacity (lack of buses, reduced punctuality). Increased operational risk necessitates maintaining reserve vehicles or contingency schedules.
Recommendation: Introduce operational KPIs regarding temperature-dependent availability; implement thermal preparation procedures before the crew starts work; use STAN remote monitoring and alerting systems to minimize unexpected route deviations. Plan operational reserves based on seasonal simulations.
Mechanism: TCO is not a simple sum of CAPEX and OPEX—it is an emergent result of the interaction between thermal performance, range, charging, degradation, and availability.
Data: Seasonal variance in range and kWh/km can alter infrastructure requirements and the number of buses by orders of magnitude in terms of cost (models indicate a fleet increase of hundreds of units in scenarios with increasing cooling demand for large cities).
Economic consequences: Incorrectly classifying thermal management as “HVAC” results in subsequent adjustments being made via CAPEX (larger batteries, more charging stations) or through costly operational procedures. TCO calculated without accounting for seasonal profiles rarely reflects actual costs.
Recommendation: The TCO model should include the following “first-class” variables: seasonal variance in kWh/km, actual charging throughput, tariff costs during mandatory charging windows, degradation risk, and the cost of reserve fleet. In due diligence, require fleet testing under extreme conditions or the provision of data from reference operations.
Key conclusion: thermal management is an economic parameter of the electric bus operation system—not a mere “add-on” for comfort.
Temperature management directly affects energy consumption, real-world range, charging capability, battery degradation rates, and fleet availability. In the Polish climate (cold winters, periodic heat waves), the consequences of neglecting thermal management quickly translate into measurable CAPEX and OPEX costs.
In the Polish tariff and climate environment, the profitability of BEB will largely depend on the ability to shift thermal operations to periods of cheaper energy and reduce the seasonal amplitude of kWh/km. With rising energy prices and potential connection capacity constraints, the value of preconditioning, heat pumps, and predictive management is growing faster than the cost of the battery itself. For city decision-makers and operators, this means a simple rule: investments in thermal systems that stabilize consumption and charging times usually pay for themselves faster than simply increasing battery capacity or expanding infrastructure.
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