Stefan has pioneered many energy efficient technologies in architecture during his thirty-five years at Foster + Partners. He has a growing body of high-profile work throughout the USA. A passionate advocate for sustainable and integrated design, he leads research activities with the Specialist Modelling Group and the Material Research Centre, working on extra-terrestrial habitats on the Moon and Mars. He has been professor of Integrated Design and Innovative Construction at University of Stuttgart. His publications include Sol Power, The Evolution of Sustainable Architecture.