Improvement of indoor air quality by way of using decentralised ventilation

Abstract

This study contains an analysis of indoor air quality in an office building. The analysis was carried out in real conditions. The purpose of conducted research was to determine façade-mounted ventilation unit efficiency to reduce pollution. The air was supply and exhaust from the room cycles lasting 2 min, 4 min and 10 min. The experimental research and calculation with use of tracer gas were conducted for determination of the air change rate. Carbon dioxide was used as tracer gas. The results of completed studies and calculations have shown that decentralised façade ventilation systems sufficiently reduces the concentration of gaseous pollutants. They keep the room temperature in the range of 21–22 °C and the relative humidity 28–39%. Cyclic air supply and exhaust guarantees hourly air change rate sufficient to dilute pollution. For the shortest cycle the experimental value of the air change rate equalled 2.3 h−1, and the calculated value equalled 2.2 h−1. For the longest cycle both values equalled 2.7 h−1. The conducted statistical analysis showed that the greatest average feature value of the reduction characteristic (reduction of carbon dioxide concentration) can be expected for the setting characteristic (lasting time of cycle) 10 min.