What is LCA?

Life cycle assessment adds up the environmental cost of a product across its whole life, the way unit costing adds up its money cost. Every product carbon footprint and every EPD is an LCA underneath.

In one line

Bill of materials × emission factors, following the rules of a standard.

Life cycle assessment (LCA) is the compilation and evaluation of the inputs, outputs and potential environmental impacts of a product system throughout its life cycle. That is close to the definition in ISO 14040, and every word matters:

• Inputs and outputs: materials, energy, emissions and waste, counted in physical units.
• Potential impacts: LCA estimates what those flows could contribute to climate change, acidification, resource depletion and so on. It does not measure harm at a particular place and time. That’s a risk assessment.
• Product system: not just the factory. The whole chain of processes needed to deliver the product’s function.
• Life cycle: from raw material extraction (“cradle”) through production, use and end of life (“grave”), unless the study deliberately stops earlier, for example at the factory gate.

Three ingredients

1. A bill of materials. What goes into the product and how much. The same list you use for costing.
2. Emission factors. The environmental “price” of one unit of each input, usually from a database. Lesson 3 shows where they come from.
3. A standard. The rulebook: ISO 14044 for LCA, ISO 14067 for carbon footprints, EN 15804 for construction EPDs.

Four phases

ISO 14040 and 14044 split every study into the same four steps. You go back and forth between them as you learn more. Lesson 2 takes each in turn.

#	Phase	What happens
1	Goal and scope	What you study, why, and where the boundary is.
2	Inventory	Every input and output, in physical units.
3	Impact assessment	Flows turned into impacts, such as kg CO₂-eq.
4	Interpretation	Hotspots, sensitivity, and what you can claim.

Worked example

One painted steel panel, cradle-to-gate, climate change only. Hypothetical teaching numbers: the factors are calculated from the process data in lesson 8, with IPCC AR6 GWP₁₀₀ values.

steel        4 kg    × 1.9855 = 7.942
paint        0.25 kg × 2.579  = 0.645
electricity  3 kWh   × 0.3766 = 1.130
─────────────────────────────────────
total                           9.717 kg CO₂-eq per panel

The factors are in kg CO₂-eq per kg or per kWh. Steel’s factor already includes the electricity used to make the steel, which is why it is more than the 1.7 kg of CO₂ the steel process emits directly.

Why “life cycle” is the point

Looking at one stage in isolation shifts burdens rather than removing them. A lighter car body made from aluminium uses less fuel in use but more energy in production. An electric kettle’s impact is almost all electricity in use, so a “greener” plastic casing barely moves the result. You only see these trade-offs if you look at the whole life cycle and at more than one impact category.

LCA and its relatives

People use these terms loosely. They are not interchangeable.

Term	What it is	Governing standard
LCA	The general method. Many impact categories, any scope.	ISO 14040, ISO 14044
Carbon footprint of a product (CFP / PCF)	An LCA restricted to one impact category: climate change.	ISO 14067; also the GHG Protocol Product Standard
EPD (Environmental Product Declaration)	A verified, published LCA report following product category rules (PCRs) set by a programme operator.	ISO 14025; EN 15804 for construction products
PEF (Product Environmental Footprint)	The EU’s harmonised LCA method, with category rules (PEFCRs).	EU Commission Recommendation (EU) 2021/2279
Corporate footprint	Emissions of an organisation, not a product. Scope 1, 2 and 3.	GHG Protocol Corporate Standard, ISO 14064-1

A useful rule: an EPD is an LCA packaged to a strict recipe and checked by a third party. A PCF is an LCA that only looks at one indicator. The underlying method is the same.

When do you need a full LCA?

• Internal decisions (eco-design, hotspot finding): a screening LCA is often enough. It uses more generic data and a simpler scope, but should still follow the method.
• Customer or tender requirements: usually an EPD or a PCF to a named standard.
• Public claims that your product is better than a competitor’s: ISO 14044 calls this a comparative assertion disclosed to the public and requires a critical review by a panel of interested parties. Don’t make these claims casually.

The practitioner's first question

Before any data collection, ask: what decision will this result inform, and who will read it? The answer sets the scope, the data quality you need and whether you need verification. Lesson 4 is built around this question.

Check yourself

Which phase decides whether transport to the customer is included?

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Goal and scope. The system boundary is set there, before any data is collected.

What you should now be able to do

• Explain LCA in one sentence to a colleague.
• Tell a colleague whether they need an LCA, a PCF or an EPD for their request.
• Recognise when a claim would count as a comparative assertion.