The iServ project ("Inspection of HVAC Systems through continuous monitoring and benchmarking") has been set up to measure how much energy HVAC systems consume when used in different types of buildings in the European Union. To achieve this objective, monitoring of more than 1600 heating, cooling and ventilation systems (HVAC systems) in Europe is set up and the data collected are analysed. iSERV also aims to show the ability of automatic monitoring of HVAC systems in the process of reducing energy consumption in practice, and to compare this with the findings of the HARMONAC project, which indicated possible costs and savings through regular conventional inspection.