Buildings are constructed airtight for reasons of energy saving and efficiency. The natural ventilation by infiltration and windows in airtight buildings does not ensure a sufficient air exchange for the wellbeing of the occupants and to remove moisture. Indoor odours are more frequently becoming a cause for user complaints. The sources of odours are mainly found inside, but odours also can be brought in from outside the building. These include construction products, materials for interior design, and furnishing including their emission and decomposition products, technical equipment, structural damage, animals, and the occupants themselves. In closed rooms, persistent odours, the existence of which occupants cannot control, are mostly considered objectionable. Exposure to such odours can lead to a decline in both the well-being and productivity of the occupants. This part of ISO 16000 describes the procedure for the determination of indoor odours with trained or untrained panels. It describes assessment methods and planning, preparation, and execution of the olfactory tests. It also includes criteria and requirements for selection of panel members. The methods can be applied to sensory evaluation with regard to acceptability, intensity, and hedonics. Olfactory tests of indoor air can either be conducted on site or in a laboratory. In the latter case, air is collected from the site and transported to the laboratory in sampling containers. It is necessary to record the physical conditions in the room during the testing or the sampling of the air, as they can influence the perception of the odours. For the overall assessment of the indoor air, it is recommended that chemical tests be carried out in addition to the sensory tests since a health assessment is not possible only on the basis of the odour test. Sensory odour tests of indoor air can meet a variety of objectives. These include finding the cause(s) of unpleasant or objectionable odours, determining the reasonability of odours and the usability of affected rooms, and inspecting the results of renovation work. Objectives of assessment of odours. When seeking the cause of odours, it is wise to conduct additional laboratory tests on samples of the component materials according to ISO 16000-28, to specify a polarity profile or to determine the type of odour. In the process of locating odour sources by means of olfactory tests, it is necessary to take into account the fact that the odour compounds can also secondarily accumulate on other surfaces, which exacerbates locating the source. The olfactory testing is appropriate for office and administration buildings, assembly halls, residential buildings, and other habitable rooms in which the comfort and health of the occupants is of interest. The test criteria in this part of ISO 16000 are not applicable to factory buildings and workshops or other rooms in which odours unavoidably stem from the production processes (kitchens, bakeries etcetera). It depends on the measurement task if the determination of the hedonics or polarity profile can be used as a complementary method. The document is directed at representatives of test facilities, supervisory authorities, trade associations and planning/architectural offices as well as representatives of interior designers, the furniture industry, the paint industry, the adhesives industry or other branches producing items for the interior. The International Standard has been prepared by ISO/TC 146/SC 6 "Indoor air" in Working Group 14 "Sensory assessment of building materials and products", the chairmanship and secretariat are held by DIN. The responsible German committee is NA 134-04-04-01-16-01 AK "Sensorische Prüfung" ("Sensory testing").