This paper aims to critically examine the issue of rendering historic buildings energy effi cient. Although this subject has been discussed to some extent on the national and international levels, it largely has been under-theorised as the existing literature focuses mainly on technical matters related to the improvement of energy performance. Indeed, one of the main issues which has not been thoroughly addressed in the literature is balancing conservation needs on the one hand and improved energy performance of historic buildings on the other, partly due to improper analytical tools, methods, and parameters that are commonly used to classify the energy behaviour of historic buildings. It is the matter of insuffi cient existing too...