No other concept has disturbed and disfigured our understanding of energy more than the seemingly innocent idea of isolation. Further, no other material practice in architecture has systemically reinforced this errant idea than insulation. In too many cases, architects and engineers treat buildings as increasingly "efficient" isolated systems without any regard for the larger energy hierarchies of a building. This is the exact opposite of how architects should engage energy. This book is a history of a most common material/energy practice in architecture: heat transfer and insulation. But this history aims for decidedly uncommon futures for architecture: fulfilling the potential of non-isolated thermodynamics in architecture. Much more than walls was insulated in modernity: in the course of modernity, insulation became a highly active physical, conceptual, and historical agent in the determinant habits of twentieth century architectural design and its associated construction practices. Non-isolated, non-equilibrium thermodynamics drive every building, city, and form of life. Their understanding helps architects grasp century-old thermodynamic concepts that position designers to finally capture, channel, intercept, store, accelerate, and modulate the total energetic dissipation of building through design.