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.
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