Some claim that C2C certification may not be entirely sufficient in all eco-design approaches. Quantitative methodologies (LCAs) and more adapted tools (regarding the product type which is considered) could be used in tandem. The C2C concept ignores the use phase of a product. According to variants of life-cycle assessment (see: ) the entire life cycle of a product or service has to be evaluated, not only the material itself. For many goods e.g. in transport, the use phase has the most influence on the environmental footprint. For example, the more lightweight a car or a plane the less fuel it consumes and consequently the less impact it has. Braungart fully ignores the use phase.