An often neglected area. Two interesting approaches for different scales
1. CROHM: Carbon Reduction Options for Housing Managers. Housing stock carbon assessment.
An interesting idea in this emerging field. I am not sure what the methodology is. It reads as a standard bottom-up approach which relies on coupling a building physics engine with housing Archetypes. There are no details however. Also offers some GIS.
2. AssetMap. A process and tool developed by Arup’s. Some references can be found below.