This thesis explored the energy conservation requirements necessary to retrofit existing historic structures. Residential and small commercial buildings were selected as significant examples. This study discussed and analyzed the historic, climatic, technical, and economic contexts which impact the energy conservation strategy. The major economic and architectural benefits were identified and described. A methodology was developed incorporating feasible retrofitting measures for historic buildings. This included technical and economic ranking of retrofitting measures with prototypical building type studies documenting the theoretical thermal performance before and after incorporation of retrofitting measures.