We find ourselves at a critical juncture: after decades of fragmented and limited action, we are experiencing a climate emergency. The built environment, which includes the housing sector, is a significant contributor of greenhouse gas emissions and wider environmental impact. Any transition to a low carbon future must include the housing sector and prioritize delivery of sustainable housing. This book explores the role that sustainable housing must play in the transition to a low carbon future and how we can provide that type of housing. This chapter explores the changing world we face, largely from a changing climate, and what this means for the built environment. We then discuss why housing is important and what benefits and opportunities sustainable housing can provide. Following this, we reflect on why, given the benefits of sustainable housing, we find ourselves facing ongoing challenges with changing the housing sector around the world. We conclude the chapter with an overview of each chapter in the book.