How to Read an EPD: A Verifier's 10-Minute Guide

EPD counts grow every year; they enter tender specifications, green building schemes and now the CPR’s environmental sustainability framework. What we see in practice, though, is this: EPDs are produced, published — and very often misread. This article walks through the reading order of a verifier who has reviewed hundreds of them: which page comes first, which number says what, and what it does not say.

Identity first: the declared unit

Every figure in an EPD is tied to its declared unit (or functional unit): 1 tonne of steel, 1 m³ of concrete, 1 m² of cladding? Any value read without the unit is meaningless — a GWP given per m² and one given per kg can differ by orders of magnitude, and both are “correct”.

The verifier’s reflex: find the unit and any conversion factors the moment you open the document. If density, area weight or coverage conversions are not in the tables, converting to another unit is on you — and that is where error creeps in.

Then the boundary: which modules are covered?

Under EN 15804 the life cycle is split into modules: raw materials and manufacturing (A1-A3), construction (A4-A5), use (B), end of life (C) and beyond the system boundary (D). Two critical questions:

• Which modules does this EPD declare? An EPD covering only A1-A3 (“cradle to gate”) cannot be compared, total to total, with one covering A-C.
• What is the “total” a total of? The A1-A3 sum describes the production stage — not the product’s lifetime impact. For materials with a heavy end-of-life scenario, the C modules can change the picture materially; module D is reported separately and is not added to the total.

The rulebook: PCR and standard version

Every EPD rests on a PCR (product category rules), and the PCR governs how the calculation is done. PCRs from different programme operators can diverge in the details for the same product group; the standard version matters too — indicator sets and rules changed between EN 15804 +A1 and +A2. Comparing EPDs built on different PCRs or different standard versions is the comparison mistake we see most.

The assurance layer: the verification statement

At the end of an EPD sits a statement of who verified it and in what scope. Two things to pin down:

• What does verification confirm? Conformity of the declaration with the PCR, EN 15804 and ISO 14025, and traceability of the data. Not that the product is environmentally friendly — an EPD is a standardised information card, not a performance grade.
• Validity: EPDs have validity periods, and an expired EPD is not accepted in tender and compliance contexts. Checking the date takes ten seconds; not checking it can cost real money.

Data age and representativeness

An EPD with an old reference year, or one resting on an industry average rather than your facility, may no longer represent today’s production. That is precisely why Buy Clean-style programmes in the US require facility-specific EPDs: an average binds no one.

The three most common misreadings

1. Comparing GWP without equalising units. Different unit = no comparison.
2. Taking the A1-A3 total as “the product’s carbon footprint”. That is the production stage; no generalisation without looking at coverage and scenarios.
3. Treating verification as a quality stamp. Verification is a conformity check; the judgement is the reader’s job.

This article describes the general structure under EN 15804 and ISO 14025; for the rules applying to a specific product group, the relevant PCR governs.