After looking at the main sources of greenhouse gas emissions from key building materials over the whole life cycle, this chapter continue with this subject looking at the various decarbonisation options, including all related energy inputs at each stage. Without an extended deep dive into technical aspects of material science, this chapter serves only as a summary of some of the key actions that are currently attainable or within reach. The radical concept of degrowth is also ignored, the current forecasts for rapidly urbanising economies suggest the opposite of degrowth. Some clear indications of actions taken come from a review of what some of the biggest property developers are doing. It includes sustainable design as well as decarbonising the manufacture of various hard to abate building materials. The role of procurement, partnerships and circularity are also considered. Building operations are considered in the next chapter.