What is a life cycle assessment?

A life cycle assessment is a systematic mapping of the environmental and resource impacts of a product, from the extraction of raw materials until the product is disposed of or recycled. The assessment covers everything that happens along the way: manufacturing, transport, installation, use, maintenance and waste handling.

The point is to see the whole picture. A product may have low emissions at the factory, but high emissions from its raw materials or transport. Without an LCA, it is easy to optimise the wrong part of the life cycle.

The four phases of an LCA

ISO 14040 and ISO 14044 divide an LCA into four phases:

1. Goal and scope: What should the study answer, and what should be included? This is where the functional or declared unit (for example 1 m² of flooring or 1 tonne of steel) and the system boundaries are defined.
2. Life cycle inventory (LCI): Collection of data on everything that goes into and out of the system: raw materials, energy, transport, emissions and waste.
3. Life cycle impact assessment (LCIA): The data is converted into environmental impacts, for example kg CO₂ equivalents for climate change.
4. Interpretation: The results are analysed. Where do the impacts occur, how reliable are the figures, and which improvements have the greatest effect?

The life cycle in modules: from A1 to D

For construction products, the EN 15804 standard divides the life cycle into fixed modules. This makes it possible to compare products and combine them when calculating the impact of a whole building.

Module	Life cycle stage	Examples
A1–A3	Product stage	Raw material supply, transport to factory, manufacturing
A4–A5	Construction	Transport to site, installation
B1–B7	Use stage	Maintenance, repair, replacement, energy and water use
C1–C4	End of life	Demolition, transport, waste processing, disposal
D	Beyond the system boundary	Benefits from reuse, recycling and energy recovery

An assessment can cover all or part of the life cycle. Cradle to gate stops when the product leaves the factory (A1–A3). Cradle to grave covers the entire life cycle. Cradle to cradle also takes into account that the materials are used again.

Which environmental impacts are measured?

An LCA measures more than greenhouse gas emissions. Under EN 15804+A2, the reported indicators include:

• GWP – climate change: Contribution to global warming, measured in kg CO₂ equivalents.
• ODP – depletion of the ozone layer.
• AP – acidification of soil and water.
• EP – eutrophication of freshwater, marine and terrestrial environments.
• POCP – photochemical ozone formation, which contributes to ground-level ozone and smog.
• ADP – depletion of resources, both minerals and metals and fossil resources.
• WDP – water use.

Resource use, waste and output flows are also reported. Read more about each category in Environmental impact EN 15804+A2.

What is LCA used for?

• Documentation: LCA is the basis for EPDs, which are required in many tenders and used in carbon calculations for buildings.
• Product development: The assessment shows which materials, processes or suppliers have the largest impact, and where improvements pay off.
• Early-stage design: LCA can compare technical alternatives before decisions are made.
• Purchasing and sales: Verified figures make it possible to document a lower carbon footprint without breaching the rules against greenwashing.

LCA and EPD – what is the difference?

LCA is the analysis itself. An EPD (Environmental Product Declaration) is a concise document that presents the results of an LCA according to fixed rules. The EPD is third-party verified and published by a programme operator, so that it can be used as documentation in the market.

In other words: every EPD is based on an LCA, but not every LCA becomes an EPD. Read more in What is an Environmental Product Declaration (EPD)? and EPD – a short guide.

Questions and answers