This document provides a strategy and methodology for sustainable refurbishment of an existing building and evaluation of the potential of sustainable refurbishment, as a means of contributing to the circular economy, to support the decision-making process. Sustainable refurbishment aims to close the gap between current performance and current requirements fulfilling national regulations, and contribute to meet sustainability goals which maximize the environmental, social and economic performance. It also aims to allow the adaptability to fulfil future needs. It can be used for a building or part(s) of a building, as well as a portfolio of buildings.