I think that one barrier to building sustainably is the whole “bigger is better” mentality, the idea that a building has to be large enough to accommodate every possible use, way bigger than is necessary than is needed for 99% of its daily functions. McCormick Place is a good example; it’s a grand building, but 70 foot ceilings? Really? I can see the appeal–the building is aesthetically attractive, but how do we learn to fight the bigger is better urge and keep footprints small? Most of these exhibit halls could have a 20 foot ceiling instead. It’s hard to fight the monumental impulse of architects and politicians.