The benefits of reusing historic and existing buildings versus those of constructing new buildings are frequently discussed considering economic, cultural, and design values. If those discussions are expanded to include environmental impact, one must address the topic of embodied energy. Due to the recent focus on sustainable construction practices; conservationists have explored the benefits of building conservation in relation to embodied energy calculations. Such studies are popular in international market and became important ground for expanding restoration practices. In our local context it is comparatively a newer domain.Different methodologies have been devised by Advisory Council for Historic Preservation (ACHP), in year 1979, for assessing the embodied energy calculations in historic structures. For performing the respective study, inventory model of assessment has adopted. The focus of this study is “to provide practical guidance on how to calculate embodied energy/ u-value in historic structures of Karachi and promote the concept of adaptive reuse from the environmental perspective”. “If more widely and comprehensively used, embodied-energy assessment can be a benefit to preservation and sustainability advocates alike.”Mike Jackson