The principles of a new tracer gas technique is described in the paper. The new technique involves pulse injection of tracer gas and has the same advantages as the previously known homogeneous emission technique. It can for example advantageously be used in large buildings and buildings with many rooms and yields information on the distribution of ventilation air within the building. However, contrary to the homogeneous emission technique, yielding the average ventilation performance during an extended time, the new technique allows measurement during short term periods. The new technique is based on homogeneous pulse injection, which means that pulses of tracer gas are injected in each zone in a zone-divided building, with amounds which are proportional to the zone volumes and integrating sampling of tracer gas concentration. Theoretical and practical aspects of the technique are described.