Why Not?

Last week, I took my students on a tour of Portland's Burnside Rocket Building. I have taken several classes to see this building, as the architect, Kevin Cavanaugh, found some amazing ways of incorporating sustainability into the design.
My favorite aspect of the building is the rooftop garden, where the restaurant located on the top floor, Noble Rot,  grows produce all year long. Although yields are fairly low this time of year, during the late summer, more than half of the produce on their menu is grown on the roof. Can't get much more local than that, can you?
So today, I asked myself why all new building aren't designed this way? Not only could we all be growing food on our roofs, but the soil would act as an insulating layer to save on energy costs, we would create new habitat for wildlife on our roofs, it would reduce the warming effect of normal black-colored roofs, and hey- it is just cool. So, seriously, why not?
So, let's just say this is the start of a revolution. Let's grow food on roofs! Spread the word!