FUNCTION - Function is obviously the most important aspect of planning and design. Unfortunately, given what seemed like a never-ending supply of natural resources, sustainability was not always considered to be an aspect of function. Sustainability relates to the question as how our built environment supports or detracts from the livability of ourselves and the natural environment that we are a part. This is the paradigm shift that is now occurring - i.e. the consideration of sustainability in the planning and design of our built environment.