In order to avoid demage to the health of occupants, annoyance or reduction in amenity and demage to the building fabric the concentration of indoor air pollutants has to be held below pollutant specific levels. One appropriate measure for the control of concentration is ventilation. In several national and international activities in the past, among others in the IEA's Annex IX "Minimum Ventilation Rates" and standardization efforts in Germany and other countries, ventilation rates have been defined which should meet both indoor air quality (iaq) requirements and energy conservation.
The new proposal for ventilation requirements in the National Building Code of Finland is on public review. The structure of the proposal is different from the existing ventilation code. Minimum requirements for acceptable indoor climate will be given to a wider extent than before, eg new requirements for indoor air temperature and purity are proposed. Also the quality of outdoor air should be taken into account in design of ventilation. Health aspects are also considered, based on today's international knowledge of indoor air quality and human health.