Life cycle assessment (LCA)

Life cycle assessment is a standardized method, defined by ISO 14040/14044, for quantifying the environmental impacts of a product or service across its full life cycle: raw material extraction, manufacturing, distribution, use and end-of-life disposal or recycling. A "cradle-to-gate" LCA stops at the factory door, while "cradle-to-grave" covers the whole span.

An LCA is built from an inventory of every input and output at each stage, materials, energy, water, waste, converted into impact categories such as carbon footprint, water use and eutrophication using per-unit emissions factor and impact data. This differs from carbon accounting, which totals an organization's operational emissions over a year rather than a single product's cradle-to-grave footprint, though the two share methods and data sources.

LCAs matter because they reveal impact hotspots a narrower view would miss, for example showing that a product's use phase outweighs its manufacturing footprint, and they inform ecolabeling, procurement and ESG reporting disclosures. The main pitfalls are inconsistent system boundaries between studies, which make LCA results hard to compare across products, and allocation choices for shared processes or by-products that can materially change the result.