Buildings account for more than one third of the world’s primary energy demand, and a large part of resource use. There is, however, enormous potential to save energy and operate buildings without producing CO2. How can we manage our existing building stock to dramatically reduce energy and resource use, in time and at scale? Peter Richner moderates a panel discussion within CCES/AGS Annual Meeting 2009. His guests are: Hansjürg Leibundgut (ETH Zurich), Ryozo Ooka (University of Tokyo), Leon Glicksman (MIT), Carl-Eric Hagentoft (Chalmers University of Technology)