This paper reports a study of a unique system that integrates many renewable energy resources to achieve zero CO2 emission for building services for the head office of a company specialised in renewable energies. A dynamic thermal model was developed to simulate the summer cooling using both design criteria and recorded data. The monitored data acquired by the Building Management System (BMS) were also analysed with the predicted results to assess thermal performance of the system. It was concluded that the cooling was adequate for most of the time during moderate summer conditions but could be insufficient when extreme heat occurs such as in 2006. The current operation of the system could be modified to improve cooling quality, including automatic control of the building’s ridge lights to allow heat to escape and to use night cooling.