Flag a claim as comparative when it says or implies that one product, product category, supplier, brand, trader, or business activity is greener, cleaner, lower-impact, more recyclable, more durable, or otherwise environmentally preferable to another. Comparisons need a common method, comparable products or suppliers, material and verifiable features, and a way to keep the comparison current.
The comparison file should name the compared products or suppliers, the function being compared, the environmental characteristics used, assumptions, data sources, calculation method, update trigger, and any limits. A broad comparison should be narrowed if it only supports one attribute, one life-cycle stage, one market, or one version of the product.