In the long-term performance analysis of the built environment, classification systems are seen as a key consideration. When classifying residential building objects, characteristics such as accuracy, exhaustivity, and consistency are required. It is noticeable that while organizations around the world are working to develop an internationally agreed standard classifier, the use of national classification systems remains widespread. Therefore, this paper focuses on reviewing the most popular classification systems such as CoClass, Uniclass 2015 and OmniClass®, among others, and discusses their strengths and weaknesses, in order to be useful both to the research and technical communities. Based on this, two main contributions are derived. On the one hand, the paper points out that there is no international consensus to use a common classification system. On the other hand, some recommendations are given and illustrated to meet the challenges of classifying existing buildings, in particular under a functional assessment approach.