The EU Directive for building energy performance requires all member states to reduce energy consumption and CO2 emissions in the existing building stock. A key instrument in achieving this is using building stock modelling as a tool for planning and development of policies. But since the building stock as a whole is a complex element to study, new interdisciplinary methods are required to facilitate a sustainable management of the built heritage. Moreover, as the goal of energy conservation is brought into a supposed conflict with the built heritage, the field of integrated conservation has a responsibility to be a part of the development of such methods. This thesis accordingly investigates state-of-the-art building stock models from several disciplines with the aim of developing a new method for categorising historic building stocks. The historic buildings in the case study of World Heritage Site Visby, Sweden, were surveyed and triangulated using e.g. on-site inspections, digital cadastre maps, the national EPC database and existing inventories, ultimately leading to 1048 buildings from before 1945 being included in a new inventory. This inventory, along with tools acquired from previous buildings stock models, enabled an iterative process to develop and validate the new categorisation method. The proposed method itself is based on the principal idea of categorisation where the building stock is represented by a limited number of categories which allow for further typology investigations, e.g. energy modelling, and extrapolation back to district level. The results show that the building stock can be represented by nine physical categories covering 86 % of the total number of buildings, and 70 % of the entire building volume. To encompass aspects regarding cultural heritage significance, the respective historic character of the buildings are assessed and described by combining statistical information and the Conservation plan of Visby. In all, the method shows to provide a supportive platform for investigations of a trade-off between energy conservation on one hand and building conservation on the other. / EFFESUS / Spara och Bevara