Environmental Product Declaration (EPD)

An Environmental Product Declaration (EPD) is a standardized, independently verified document that reports the environmental impacts of a product over its life cycle. EPDs are used across construction, including for roofing membranes, shingles, metal panels, tiles and insulation. They are a transparency tool: they disclose data so that products with the same function can be compared, but they do not certify that a product is environmentally friendly.

Standards

• ISO 14025 defines Type III environmental declarations, the category EPDs belong to, and sets the procedures for developing product category rules.
• ISO 14040 series sets out the life cycle assessment (LCA) methods on which EPDs are based.
• EN 15804 (current version EN 15804:2012+A2:2019/AC:2021) is the European common product category rule for construction products.
• ISO 21930:2017 provides core rules for construction products and is commonly used by programme operators in North America and Asia.

Product category rules (PCRs)

A PCR specifies how the LCA must be carried out and reported for a type of product, such as single-ply membranes or metal roofing. Sub-PCRs add detail for product subgroups. Following the same PCR is what makes EPDs within a category comparable.

Verification

Before publication, an EPD must be checked by an independent third-party verifier, who reviews the underlying LCA background report. The background report itself is usually not published.

What an EPD reports

EPDs typically report indicators such as global warming potential (embodied carbon), ozone depletion, acidification, eutrophication, smog formation, resource use and waste. They state which life cycle stages are included, for example raw material supply and manufacturing only (cradle to gate) or the full life cycle including use and end of life.

Using EPDs for roofing decisions

• Compare products only on the same functional unit (for example, per square metre of installed roof over a stated service life).
• Check the life cycle stages covered; a cradle-to-gate EPD omits replacement and end-of-life effects that matter for roofs.
• Note whether the EPD is product-specific or an industry-average EPD.
• Consider service life and recyclability, which strongly influence a roof's lifetime impacts.

EPDs are increasingly required by green building rating systems and by public procurement policies such as Buy Clean laws.