Comparison of the Efficiency of Building Hybrid Ventilation Systems with Different Thermal Comfort Models

Abstract

Building hybrid ventilation integrates the advantages of both natural ventilation and mechanic ventilation. Ventilation efficiencies and system costs are found to be associated with different control strategies. Two indoor thermal comfort indices, which are predicted mean vote (PMV) model and adaptive comfort standard (ACS) model, are chosen as the control objective in this paper. A hybrid ventilation system with these thermal models was developed. Experimental tests were conducted to compare the time percentage of thermal comfort in summer, and the running time of the exhaust fan between the two systems. The results show that the percentage of the interior thermal comfort time is between 64.5% and 86.4% when the outside air temperature is between 10°C and 25°C (the average temperature is about 17.5°C, Period 1). The percentage is 45.2∼60.7% when the outside air temperature was 13∼32°C (the average temperature is about 22.7°C, Period 2), and 29.4∼49.3% when the outside air temperature was 18∼34°C (the average temperature is about 26.5°C, Period 3). The comfort time percentage is always higher with ACS model than that with PMV model in these three test periods. The results also indicate that the ventilation efficiency, which is defined as ratio of window opening time to the fan's running time, is higher with the ACS model than that with the PMV model in the period 2 and 3. The ACS model could be considered as the prior control objective for the hybrid ventilation system.