On Monday, 2014 Pritzker Prize winner Shigeru Ban sat down with New York Times architecture critic Michael Kimmelman at the NYT Cities for Tomorrow conference to discuss Ban’s pro bono work in disaster areas, use of recycled materials and the true meaning of permanence in architecture. We also had a chance to speak to the Japanese architect about his thoughts on sustainability, and were a bit surprised at his answer. Read on to see what he had to say.