Kinetic Architecture: Designs for Active Envelopes is a book about energy. We have written it to explore the new ways architecture has developed in the last decade to respond to the flow of energy, both natural and man-made, that primarily affects building performance and the comfort of the people in them. Buildings regulate energy flow in several ways, but in this book we explore the approaches that innovative architects, engineers, and consultants have taken with building envelopes, façades, and other types of enclosures that modulate the internal environment of architecture to various ends. Architects have expressed this regulation in ways both visible and invisible, using the media of air, water, and the thermal mass of a variety of materials, and often a combination of all three.