This report falls under the activities carried out in WP5, Task 5.2 (Definition of concepts and KPIs). The goal of WP5 is the development and validation of a multi-dimensional assessment model (MDAM) for identifying the most appropriate deep energy retrofitting solutions for heritage townhouses within a holistic assessment framework. The goal of the multi-dimensional assessment model is to streamline the evaluation process of energy retrofitting solutions for historical townhouses and the interaction occurring between Building Conservation Authorities and building owners and designers. By defining a set of indicators and their calculation methods, HeriTACE aims to provide the actors involved with a clear, detailed, and objective tool for the evaluation of the performance of deep energy retrofitting solutions.