You can get the operating energy down, sure, but what about the materials, and the construction process? Even a simple adobe hut built with no machinery has some footprint. For most buildings, that’s a big big big big footprint.
and while we’re at it . . .
Any good building is a high embodied energy building. Deep green and natural builders understand that there’s plenty of energy available from sun, wind, and human beings — both their muscles and their smarts — to make very high quality buildings. We’ve been doing it for centuries. Good building takes a lot of energy — it just doesn’t have to be fossil fuel energy.