Ventilation rate in modern flats. Luftskiftet i nyere boliger.

Reports measurements of air change rates carried out in the living rooms of 39 flats built during the last 20 years using Freon 12 as a tracer gas. Ventilation rates ranged from 0.3 to 2.9 changes per, hour, the average being 1.3 changes per hour. Air temperature, humidity and wind speed were recorded and the ventilation rates corrected for wind speed and temperature. Notes large ranges in ventilation rates for similar flats. Finds that ventilation rate depends on wind velocity, indoor/outdoor temperature difference and the construction and use of the flat and it is therefore meaningless to state the ventilation rate without defining the conditions which apply. Suggests ventilation rate should be adjusted to the degree of pollution of the inside air rather than simply fixing the ventilation rate.