As described in the previous chapters, the continuum of sustainability actions in the built environment is multifaceted. A holistic approach is required but can deliver significant cuts of around 80% in operating carbon in existing buildings while new developments can use various means to reduce embodied carbon. Successful precedents from other industries and case studies in a range of locations show how much is already being done elsewhere but more needs to be done in the built environment. Most importantly, there is a clear and demonstrable business case for all stakeholders to take action. Most of the tools and technology required are available today, or understood and still a bit of a stretch away. It is acknowledged that retrofitting high value buildings is relatively straightforward and less easy for lower value buildings. In both cases, it is a huge challenge to do it at scale across a whole market and within the timeframe that Nationally Determined Contributions demand. This requires innovation, new approaches, workable technology solutions and scaleability. Most of what we need already exists except a real sense of urgency, a systemic approach, deep understanding and political determination.