It means one's environment, but not strictly the physical environment. It can also refer to the social, historical and psychological environment. We think about ALL of it in our design work.
Design, as a discipline, isn't just about aesthetics, although that is the most arresting aspect. It is also about a very intense psychological relationship between humans and their environment. Understanding that relationship, improving it, personalizing it, is a designers first obligation. That, and making sure it doesn't kill anyone. We design in a socially and environmentally responsible manner.
1. Safety. Just because something is recycled or renewable doesn't mean it is suitable for the job. We can't have our building environment hurting us or our natural environment.
2. Durability. If it falls apart (or looks bad) and has to be replaced repeatedly, that isn't sustainable. This means that the aesthetic should be durable too, because TRENDY will look DATED in a few years and get replaced, even if it's not worn out.
3. Conservation. The least expensive energy or material is the one you don't use. Sustainable design is not more expensive in the long run.
4. Education. Occupant engagement is crucial to the sustainable function of any built environment. We aim to allow sustainable action and habit to be easier than any other.