Rooftop greenhouses. You either love them or hate them. If you're in the second camp, you may want to think again. Xavier Durany of the University of Barcelona knows all about the positive results that can be achieved by integrating a rooftop greenhouse in a building, and he recently presented those at Wageningen University & Research, as part of a series of lectures in connection with the Urban Greenhouse Challenge, in collaboration with the GROOF project.