This introduction covers some key concepts discussed in the subsequent chapters of this book, which can change the way buildings are designed. A principal aim of the book is to show from practical experience how to reduce carbon footprint through the construction and use of buildings. The carbon emissions impacts of constructing and maintaining buildings over their lifetimes are increasingly significant due to the success of the Building Regulations and BREEAM in reducing operational energy usage. In most new building types, lifetime embodied carbon emissions can now exceed the regulated operational emissions from day-to-day energy use. Material-related or ‘embodied’ carbon emissions are therefore crucial in making further progress.