1.1 Sustainabilty has three types of general principles: environmental, economic, and social. This guide covers the fundamental concepts and associated building characteristics for each of the general principles of sustainability. 1.2 This guide distinguishes between ideal sustainability and applied sustainability. Ideally, human activities would not require making trade-offs among environmental, economic, and social goals. However, this guide recognizes that, in applying sustainability principles to buildings, decision makers must often balance opportunities and challenges associated with each of the general principles. 1.3 This guide identifies general methodologies associated with the decision-making process used in pursuing sustainability