Determination of air exchange rates for demand controlled ventilation.

In this paper the required ventilation air flow rates in residences with different pollutant loads are considered. The calculative study was carried out by using the load data presented in the literature. The results of the study were applied in the development and dimensioning of demand controlled ventilation systems. The first stage of calculations was to determined the required ventilation air flow rates (range) with different loads for each type of rooms separately. In the analysis of required ventilation air flow rates due to material emissions, the Monte Carlo-method was applied. The second stage of calculations was to analyse indoor air contaminant concentrations in an apartment as a whole using the required air flow rates in room spaces. The time-dependant occupant behaviour in the apartment was based on a certain assumption. Calculations with constant air flow rates ventilation were also done. When considering different load factors; human based odours, the odours of smoking, humidity loads and contaminant emissions of materials were taken into account. The required ventilation air flow rates in different load situations were determined to guarantee good indoor air quality and humidity conditions, and to prevent health risks due to material emissions, as well. In most calculation cases it was assumed that indoor air is fully mixed. In addition, the effect of air flows on 2- dimension contaminant field was analysed.