It is well established that buildings are the largest energy-consuming sector, using over one-third of all final energy, but the fact that performance is improving dramatically is left out of the picture. Building energy efficiency technologies have attracted over $5.5 billion in venture funding since 2000, rising against a decline in the broader cleantech segment. This, coupled with increasingly stringent building codes, and the strong momentum in adoption of voluntary third party rating schemes mean that energy efficiency is well in-hand. Leading technology providers will need to look beyond energy performance alone, to occupant comfort, health, and productivity. The interaction of buildings with the grid, people, and the cloud, will enable Building Efficiency 2.0.