Activities in the built environment are one of the largest consumers of energy use and sources of GHG emissions worldwide, including buildings and facilities in the residential, commercial, and institutional sectors, and industrial processes. Shifts toward high efficiency energy use, such as through improved equipment, appliances, building design, and operational processes can cut emissions, save money, create new jobs, and reduce climate change related vulnerabilities. CCS provides critical assessments of available technologies and practices, low carbon futures, and financial valuation along with program design and implementation mechanisms to support new or retrofitted infrastructure energy system deployment and financing for high impact, high efficiency approaches.