LCIA Methods¶

TRAILS ships built-in LCIA method sets for ecoinvent versions 3.10 and 3.11. These methods are bundled with the package data and exposed through trails.lcia utilities.

List available method names¶

from trails import get_lcia_method_names

methods_311 = get_lcia_method_names(ei_version="3.11")
methods_310 = get_lcia_method_names(ei_version="3.10")

print(methods_311[:5])

Method names are returned as strings joined with " - " from the original LCIA tuple labels.

Use methods in temporal LCA¶

from trails import Trails, lca, get_lcia_method_names

method = get_lcia_method_names(ei_version="3.11")[0]
trails = Trails(
    package,
    methods=[method],
    ei_version="3.11",
)

trails.temporal_routing(
    start_year=2030,
    start_act_idx=start_act_idx,
)

lca(
    trails=trails,
    # defaults shown explicitly:
    solver_mode="iterative",
    iterative_rtol=1e-3,
)

Call-level methods=... and ei_version=... still override constructor defaults when needed.

Use EDGES methods¶

TRAILS can also score the finalized temporal inventory with EDGES edge-level characterization factors. This requires the optional edges package and currently supports EDGES methods whose supplier matrix is "biosphere".

from trails import Trails, lca, get_edges_lcia_method_names

method = get_edges_lcia_method_names()[0]
trails = Trails(
    package,
    edges_methods=[method],
)

trails.temporal_routing(
    start_year=2030,
    start_act_idx=start_act_idx,
    # EDGES methods are final-score methods only, so this example uses
    # explicit fixed-depth routing. Use Trails(..., methods=...) as well
    # if you want adaptive routing before EDGES final scoring.
    max_depth=2,
)

lca(
    trails=trails,
    # edges_additional_topologies=topology,  # optional
    edges_reuse_cached_cfs=True,
)

Final scoring with edges_methods is mutually exclusive with regular methods in a single lca() call. In EDGES mode, TRAILS builds trails.inventory internally because edge-level CFs are applied after the temporalized biosphere inventory has been assembled. Constructor edges_methods are used only for final EDGES scoring. Adaptive routing still needs regular LCIA methods, passed with Trails(..., methods=...) or temporal_routing(..., adaptive_methods=...).

By default, edges_reuse_cached_cfs=True reuses EDGES matched CF templates across scenario years when the supplier and consumer metadata signatures are identical. The numeric CF values are still evaluated for each scenario year, which keeps yearly parameterized methods such as AWARE yearly factors year-specific while avoiding repeated exchange matching. Set edges_reuse_cached_cfs=False if an EDGES method has year-specific matching rules or year-specific CF definitions that should be resolved independently for each year.

Inspect LCIA flow factors¶

Use get_lcia_methods if you want the underlying mapping from biosphere flow keys to characterization factor values:

from trails import get_lcia_method_names
from trails.lcia import get_lcia_methods

method_name = get_lcia_method_names(ei_version="3.11")[0]
lcia_data = get_lcia_methods(methods=[method_name], ei_version="3.11")
flow_to_cf = lcia_data[method_name]

# Key format: (name, compartment, subcompartment)
print(next(iter(flow_to_cf.items())))

Matching behavior¶

TRAILS matches LCIA factors to biosphere flows using exact tuple keys:

(name, compartment, subcompartment)

If a method exchange has only one category level, TRAILS uses "unspecified" as the subcompartment placeholder.

Version selection¶

Set ei_version consistently in:

get_lcia_method_names
Trails(..., ei_version=...) or trails.lca(..., ei_version=...)
trails.lcia.get_lcia_methods

so method names and factors come from the same bundled dataset.