carculator_bus

Prospective environmental and economic life cycle assessment of city buses and coaches, including depot, opportunity and in-motion charging.

Developed at the Paul Scherrer Institute. This checkout prepares 0.1.1; see CHANGELOG.md for release status and changes.

Installation

Use Python 3.12 (>=3.12,<3.13) and a fresh environment. The shared runtime requires NumPy >=1.26.4,<2.

python3.12 -m venv .venv
source .venv/bin/activate

On Windows, activate with .venv\Scripts\activate. After publication, install this release from PyPI:

python -m pip install "carculator_bus==0.1.1"

Before publication, use the matching source checkouts as described under development. Core calculations use bundled resources and need no Brightway project, ecoinvent installation or network access. Inventory export has optional dependencies:

python -m pip install "carculator_bus[excel,brightway]==0.1.1"

The Brightway extra supports the legacy stack (bw2io<0.9, bw2data<4, bw2calc<2). Export currently targets ecoinvent 3.9 and 3.10; importing those inventories requires the corresponding background database in the destination tool.

Quick start

from carculator_bus import (
    BusInputParameters,
    BusModel,
    InventoryBus,
    fill_xarray_from_input_parameters,
)

inputs = BusInputParameters()
inputs.static()
_, array = fill_xarray_from_input_parameters(
    inputs,
    scope={"size": ["13m-city"], "powertrain": ["ICEV-d", "BEV-depot"], "year": [2025]},
)
model = BusModel(array)
model.set_all()
print(model["TtW energy"])  # kJ per vehicle-kilometre

inventory = InventoryBus(model, functional_unit="pkm")
impacts = inventory.calculate_impacts()
print(impacts.sel(impact_category="climate change").sum("impact"))

Bus model cost outputs are already per passenger-kilometre; inventory normalization is a separate choice.

Modelling and validation

The vehicle models include native 2025 parameters and documented temporal extensions. These combine engineering priors and selected calibration evidence; they are not independent measurements for every vehicle configuration.

TtW energy is in kJ/km. For BEVs it is net stored-energy depletion; model.battery_terminal_energy reports terminal DC separately, while electricity consumption is grid electricity in kWh/km. Identify the measurement boundary before comparing energy outputs. Availability-masked zeroes do not represent physically zero consumption.

Supported background scenarios are SSP2-NPi, SSP2-PkBudg1000, SSP2-PkBudg650, and static. ReCiPe supports midpoint/endpoint and EF midpoint. Use fresh model instances for independent cases. inputs.stochastic(n, seed=...) seeds parameter sampling, not every downstream cost adjustment.

See validation and limitations, migration notes and the documentation.

Development and release

Use matching sibling checkouts, especially carculator_utils 1.3.6 or newer:

python -m pip install -e "../carculator_utils[test,excel,brightway]" -e ".[test,docs,excel,brightway]"
python -m pip check
python -m pytest
python -m sphinx -b html docs docs/_build/html

The docs extra includes the extensions used by this repository. See RELEASING.md for artifact verification, release order and publication.

Support and license

Contact carculator@psi.ch or open an issue. Maintained by Romain Sacchi, with contributions from the carculator development team. See contributing. Licensed under BSD-3-Clause.