The use of Matlab, a tool for mathematical programming, is actually increasing in a large number of fields. Together with its dynamic simulation toolbox Simulink, originally developed for control and automation applications, it has become a powerful tool that is suitable for a large number of applications. In the field of building and HVAC, the number of users of Matlab/Simulink has also been increasing rapidly in the last years. The tool is suitable for many applications in this field as for example the study of energy consumption, control strategies, hydraulic and air flow studies, IAQ, comfort, sizing problems. More and more studies are being published using Matlab/Simulink environment for development of specific tools and for simulations of buildings and technical building services. This paper gives a synthesis on the use of Matlab/Simulink for the improvement of buildings and HVAC systems. The information has been gathered during two first international workshops on the use of this tool for building simulation. At these two workshops with participation of 10 countries, 33 technical presentations gave an overview on current research and studies using this tool. Some additional references are also provided in order to include other work that could not have been presented during the workshops. The paper gives an overview on the topics that are treated using the tool, the related tools that can be used, the modelled phenomena and the issues solved using the tool.