LCA Software and Modelling Tools: Flows, Parameters, Scenarios and Versioning
Building blocks
Every tool represents the same primitives: unit processes containing exchanges, product flows linked to a provider process, elementary flows to the environment, and a product system that resolves those links. openLCA works natively in JSON-LD and is free; SimaPro and Sphera LCA for Experts are commercial; Brightway is a Python library used through the Activity Browser or scripts.
Parameters and scenarios
Parameters hold numbers or formulas at global, database, group or process level. Build scenarios as alternative parameter sets rather than duplicated models, run once per set, then compare. Version the model: copy databases before editing, pin library versions, keep a changelog. A .zolca export, a Brightway project export or a Git-tracked JSON-LD dump are all valid snapshots.
Interfaces
APIs matter increasingly: openLCA's IPC server (Python olca-ipc) can create processes and trigger calculations, and Brightway exposes its whole model in Python. Automate only after the model is stable and protected by a regression calculation.
Worked example
Electricity use is 0.5 kWh per kg, and output is 1,000 kg. Define production_volume = 1000 and elec_kWh = production_volume * 0.5, then link elec_kWh to the electricity input exchange. Rerun with a ±20% sensitivity range on elec_kWh and record both results; a hard-coded 500 kWh would silently break when volume changes.
Traps
Flows left unlinked after import; unit mismatches (t versus kg, MJ versus kWh); formulas that hide a unit conversion inside a unitless number; overwriting the master database instead of a working copy; results computed with a different LCIA method version than the one reported; scenario folders that differ in more than the variable under study.