The introduction of the first Directive on the Energy Performance of Buildings (EPBD) and its consequent reforms, initiated a wide discussion on the energy efficiency and retrofit of the old building stock. As The EPBD excluded heritage buildings under statutory protection due to conservation conflicts, it soon became apparent that the old fabric and heritage value of a significant number of the old and mainly traditional buildings were at risk, threatened by incompatible interventions. Since then, a substantial amount of research projects, and initiatives were carried out, mostly examining energy efficiency and performance of the old fabric and investigating the application of energy retrofits within the frame of preservation of heritage value. However, issues such as the sustainability of the interventions, the preservation of the inherent sustainable and environment friendly characteristics, along with issues of compatibility, adaptability and resilience have not been studied extensively, even though these aspects could act as decisive parameters on the low impact operation and longevity of these buildings. The Greek old building fabric is an amalgam of integrated materials, architectural and intangible elements which express the historic and cultural evolution of the country’s built environment. This paper attempts to identify the intrinsic elements that need to be evaluated in each restoration and/or energy refurbishment work in order to dignify the proper procedures that need to be followed for low impact sustainable interventions responsive to the requirements of each certain project.