“The FNRE Guide, among other objectives, aims to guide designers towards the most appropriate approaches, in accordance with good building rehabilitation practices and following the ‘Principle of Minimum Intervention and Maximum Performance’, duly contextualized taking into account the legislation in force at the date of the pre-existence project, the legislation in force and the state of the art at the present time, as well as the future legislation, currently in preparation, indicating paths in situations of potential conflict between what is in force and what the scientific community considers to be the most appropriate approach”.