This document provides a process for the evaluation of the potential for sustainable refurbishment of an existing building, as a mean of contributing to the circular economy. This document gives guidelines to assess performance of existing buildings in order to determine what to do in a set of alternatives: Refurbish for similar or new use, use as is or tear down. Sustainable refurbishment aims to close the gap between current performance and current requirements. It can be used for a building or part(s) of a building, as well as a portfolio of buildings. This document gives a method for assessing performance of existing buildings: Technical (including energy) characteristics Usability for users Adaptability for changes Indoor environment (health aspects) Economic feasibility Embodied environmental impacts The document describes the work to be done in main applicable categories of a 5 steps process: Step 1: Evaluating the building Step 2: Sustainable deconstruction Step 3: Sustainable construction process Step 4: Sustainable commissioning Step 5: Sustainable in use Note: In this standard the users are people and organisations working in the building, including the facility management. In some building’s visitors are also important users. This approach is generic for all types of buildings. At present this document does not cover civil engineering work and it does not give benchmarks for the evaluation. Assessment of the impacts of sustainable refurbishment of buildings is covered by calculation methods described in EN 15978 part 1 to 3