At present, indoor air quality is assessed exclusively by human panels. As this method is time consuming and cost intensive, little attention is paid to indoor air quality in the planning and operation of buildings. In recent years multi-gas sensor systems have been developed in order to mimic the human sense of smell. These systems comprise an array of gas sensors, with sensors of different sensitivity and selectivity, and a data processing unit. Up to now the sensors are not sensitive enough to mimic the perception of a human being. To further the development of these systems, the European research project SysPAQ (Innovative Sensor System for Measuring Perceived Air Quality and Brand Specific Odours) was started in September 2006. It will end in September 2009.