This ACHP report from 1979 contains formulas and models for assessing the potential value of historic preservation in terms of energy conservation. Three case studies examine disparate property types - an early federal housing project, a commercial complex, and a adaptively used carriage house - and the report provides readers with tools for undertaking such analysis. The report documents how rehabilitation of historic buildings can produce significant energy conservation benefits over the life of the buildings. A summary of the findings for a general audience was published in Preservation and Energy Conservation.