Certification of energy efficient and water efficient products
Certification varies in cost reliability (the level of assurance provided). The best are essential aids to environmentally conscious and budget conscious shoppers; the worst examples are actually greenwashing.
Life cycle analysis is a key tool in certification.
Independent third-party verification is an important part of certification. If the testing is done by the company itself, there is an incentive to interpret results favorable, or even to cheat outright.