Life cycle inventory
Life cycle inventory (LCI) is the data-collection phase of Life cycle assessment that quantifies relevant inputs and outputs for a defined product system. It records flows such as materials, energy, water, products, emissions, and waste against the study’s functional unit and system boundary, creating the evidence base for later impact assessment.
In simple terms
A Life cycle inventory maps the processes within a chosen boundary, then compiles measured, calculated, or database-sourced flows for each process. Those flows are related to a functional unit, such as one tonne of material or one use of a product, so alternatives can be compared consistently. The inventory is an input to Life cycle assessment, not its final environmental interpretation. A Greenhouse gas inventory usually focuses on an organization or reporting boundary and greenhouse gases, while an LCI can cover many resource flows, emissions, and lifecycle stages.
Why it matters
The quality of an LCI strongly shapes every result produced from it. Transparent boundaries, representative data, allocation choices, and compatible datasets help analysts identify data gaps and avoid comparisons built on different assumptions. Shared data conventions, such as those supported by the Global LCA Data Access network, also make lifecycle information easier to exchange and reuse without making all datasets equivalent.
Example
For example, a fictional packaging study defines its functional unit as delivering 1,000 litres of beverage. Its LCI records raw materials, manufacturing energy, transport, product losses, and end-of-life flows for each packaging option. The resulting dataset supports comparison, but only within the stated boundary and assumptions.
How it differs
Life cycle assessment
Life cycle inventory compiles quantified inputs and outputs for the defined product system; Life cycle assessment uses that inventory with goal, scope, impact assessment, and interpretation stages to evaluate environmental implications.