What is a product life cycle? The stages from cradle to grave

A product life cycle is the whole sequence of stages a product passes through, from extracting its raw material to disposing of it as waste. Think of it as an object’s biography: where it came from, how it was made, how it travelled, how long it was used, and what became of it.

The concept should not be confused with life cycle assessment (LCA). The product life cycle is the object — the thing being measured. LCA is the method — the standardised way of measuring it. It is also confused with the marketing sense of ‘product life cycle’ (introduction, growth, maturity, decline); that is a sales concept, while this is a physical flow of matter.

The five stages

1. Raw material supply

Mining, agriculture, forestry, or the collection of recovered material. Ore extraction and beneficiation for metals; harvesting for timber; oil refining and polymerisation for plastics all sit here. For most construction materials this stage carries the largest share of impact.

2. Manufacturing

Turning raw material into product at the plant: melting, firing, forming, assembly, packaging. The energy intensity of this stage varies widely by sector — the kiln dominates in ceramics, electrolysis in aluminium, the clinker kiln in cement.

3. Distribution

Transport from the plant to the point of use, and installation where relevant. For low-density or heavy products — glass, concrete, insulation — transport distance shifts the result noticeably; for small, high-value products it usually stays negligible.

4. Use

The period in which the product performs its function: energy and water consumption, maintenance, repair, component replacement. For energy-consuming products — appliances, motors, boilers — this stage is most of the total. For passive products, maintenance and replacement frequency decide it.

5. End of life

Deconstruction, collection, transport and final treatment: reuse, recycling, energy recovery or landfill. Where the material goes at this stage can change the whole result — especially for materials carrying biogenic carbon, such as timber, and those with high recycling value, such as metals.

Mapping to the EN 15804 modules

For construction products these five stages are reported under a standard module lettering. Knowing what each letter means is the precondition for reading the numbers in an EPD correctly.

• A1-A3 — product stage: raw materials, their transport, manufacturing. The minimum set most EPDs cover.
• A4-A5 — construction stage: transport to site, installation and installation waste
• B1-B7 — use stage: use, maintenance, repair, replacement, refurbishment, operational energy and water
• C1-C4 — end of life: deconstruction, transport, waste processing, disposal
• D — recovery potential beyond the system boundary; reported separately, never added to the total

System boundary: where to stop

A study need not cover every stage, but it must say plainly where it stopped. A cradle-to-gate calculation covers A1-A3 and is the natural choice for producers selling intermediate goods. Cradle-to-grave runs through the C modules and makes sense for final products. Cradle-to-cradle describes a closed system where recycling feeds a new cycle.