The building construction industry accounts for 5% of global energy use and 10% of global greenhouse gas (GHG) emissions. A primary source of these emissions is the manufacture of building construction materials such as steel, cement, and glass. As aggressive building energy codes push new construction towards net-zero-energy and net-zero-carbon operations, corresponding efforts to reduce embodied energy and carbon from building construction materials must be pursued to achieve the decarbonization goals of the building sector. In the past few decades, progressive building energy codes as well as the underlying research on reducing the operational energy and its related greenhouse gas emissions have stimulated changes of practice in building design and operation. In contrast, strategies to reduce embodied carbon in the substitute remaining life-cycle stages of a building are less defined and studied. The selection of building materials and systems is largely unregulated, as long as minimum health, safety, and performance standards are met. In addition, it is unclear whether we have adequate knowledge infrastructure to incorporate embodied carbon into national model codes. This study provides a comprehensive review of the current state of knowledge of existing methods, databases, and tools on embodied carbon studies, and identifies the knowledge gaps. It provides a basis for the governments, academia, industry, and other institutes to collaboratively fill in these gaps and develop standards and codes to decarbonize buildings and their interface with other sectors.
Country Report on Building Energy Codes in the United States
