Research the existing stock of Environmental Product Declarations and underlying Product Category Rules in selected material categories including wood, steel, and glass. Evaluate the accuracy and comparability of the population, identify top sources of embodied carbon impact variation in the supply chain, and provide estimates of the sensitivity of the embodied carbon impact of those supply chain factors. Document these differences in formats that can be published and, incorporated into BuildingTransparency.org’s free EC3 software service, for which C Change Labs is the primary developer.