UNI EN 15804: the rules for Environmental Product Declarations (EPD)

What an EPD is

An EPD (Environmental Product Declaration) is a verified document that measures and communicates a product's environmental impacts over its life cycle, under common rules. UNI EN 15804 is the standard that sets those rules for construction products, so that the EPD of a brick and that of an insulant 'speak the same language'.

The structure by life-cycle stages

The standard organises impacts by the product's life stages: production (extraction and manufacture), transport and installation, use and maintenance, end of life (demolition, recovery, disposal), plus the benefits beyond the system boundary (for example recycling). It is the framework — known as modules A–D — that lets you move, by summing up, from the product to the whole building (with EN 15978).

Indicators, declared unit, comparison

For each stage the standard requires quantifying a set of environmental indicators — first of all the global warming potential (embodied carbon) — referred to a declared unit (for example 1 m² of panel). Only with the same category rules, unit and boundaries are the figures of two EPDs comparable.

The hard case: comparing well

The most common mistake is comparing two EPDs out of context. They are comparable only if based on the same category rule, the same unit and the same boundaries, and ideally at building level (EN 15978), where the real function counts. Likewise, stopping at the production stage alone ('cradle-to-gate') ignores use and end of life: embodied carbon must be read over the whole cycle.

Why it matters

UNI EN 15804 is the infrastructure that makes the sustainability of materials measurable and comparable: it feeds building LCA, the Minimum Environmental Criteria, the EU Taxonomy and environmental certifications. For an architecture that declares sustainability, the EPD is the proof: it turns the adjective 'ecological' into a third-party-verified figure.