As an architect and a treehugger, we have been trying to figure this out. There is so much out there that purports to be green- monster houses in the country with solar panels, straw bale second homes that people drive to in SUV's. It has to be more than a collection of systems and building materials. The State of California defines it as "a structure that is designed, built, renovated, operated, or reused in an ecological and resource-efficient manner. Green buildings are designed to meet certain objectives such as protecting occupant health; improving employee productivity; using energy, water, and other resources more efficiently; and reducing the overall impact to the environment". The National Building Museum has its own ten tips, as listed in Mairi's post. Both lists do little to take into account the larger societal issues. As we come up to the installation of a portion of a Glidehouse at the National Building Museum this spring, we wll look at this issue more closely.