Impressed with the amount of green garden rooftops in Chicago. Beautiful solutions to energy efficiency. Provides insulation to regulate interior temperatures and a place to oxygenate and relax in the city sans cutting down more trees!
Roofs that hold water: reduce heating and cooling costs, increase life of roof, and create a rooftop garden! Would be great on a shipping container home, as there might be a risk of collapsed roof otherwise if drainage isn't sufficient.