Can we compare the environmental performance of this product to that one? An update on the development of product category rules and future challenges toward alignment

Abstract When used to compare the relative environmental performance of different products, life cycle-based, quantitative environmental claims, such as carbon footprint claims and environmental product declarations require common rules in order for claims to be comparable within a category. Product category rules (PCRs), which are defined in the ISO 14025 standard, specify how life cycle environmental impacts should be estimated and reported for products within a given category. The standard has allowed for the development of multiple program operators in different countries, each with its own set of PCRs. We provide a global update on the development of PCRs, describing progress in existing programs and highlighting emerging efforts. As PCRs have begun to proliferate, challenges have arisen that could potentially undermine comparison of life-cycle-based claims for comparable products. These challenges include the definition of the product category, the lack of common data sources, limited geographic scope, and the format of the claim. We present some recommendations on overcoming these challenges and point out some potential mechanisms to support alignment internationally.