Understanding the need to educate and train in sustainable development principles and strategies, the USGBC has designed several professional credentials that demonstrate different levels of knowledge and skills for the application of the LEED Certification System. The LEED guides propose a series of design and performance strategies to be implemented in a structure with the purpose of addressing the environmental impact issues as well as the operation and maintenance costs related to excessive consumption of energy, potable water and materials. It also aims to improve the interior environment of buildings to promote the production, use and welfare of the occupants and the surrounding community.