Development of a demand control strategy in buildings using radon and carbon dioxide levels.

Air change rates, indoor radon and carbon dioxide levels were monitored in a lecture theatre in the Hong Kong University of Science and Technology. Two preliminary measurements (Cases 1 and 2) and one series of demand control ventilation simulation (Case 3) were made to investigate the indoor air quality of the lecture theatre. Radon and carbon dioxide levels were found to be relatively high in Case 1 and later improved at the expense of operating the system catering for maximum occupancy in Case 2. In Case 3, the average radon and C02 levels inside the lecture theatre were kept under 200 Bq/m3 and 1000 ppm during lecture hours, respectively. These results led to the possibility of developing a demand control strategy (Case 4) using radon and carbon dioxide levels as control parameters for fresh air intake. This new demand control ventilation has an estimated energy saving potential of 440A.