| The reduction of outdoor supply air ventilation and natural ventilation frequently increases indoor air pollution and may cause increased health risks. Moreover, control of indoor air quality (IAQ) affects energy consumption of a building as it relates to the operation of the heating, ventilating, and air conditioning (HVAC) system. Proper selection and operation of the HVAC system of a building, therefore, lead to good IAQ and to thermal comfort. HVAC systems are classified into two categories: Constant Volume (CV) systems and Variable Air Volume (VAV) systems. CV systems maintain good IAQ, but operation of CV system leads to high energy cost. Owing to reduced ventilation rates, operation of VAV systems leads to low energy cost, but increases indoor air pollutant concentrations. The Variable-Air-Volume/Bypass Filtration System (VAV/BPFS) system is designed to rectify these shortcomings of the CV and VAV systems.; The VAV/BPFS system is an electronically controlled system which provides cost-effective thermal comfort and acceptable indoor air quality by using a bypass filtration/air cleaning. system. An IAQ sensor located within the VAV/BPFS system, measures the concentration of VOCs resets the supply air temperature leaving the air handling unit, and increases or decreases the air flow through the filter assembly in the bypass duct to maintain satisfactory indoor VOC levels.; To investigate whether the VAV/BPFS system reduces indoor air pollutant concentrations and energy consumption more effectively than the conventional VAV system, A series of experiments were performed in a 32.6 m{dollar}sp3{dollar} all aluminum chamber under the same controlled conditions. Cigarettes and deodorants were used to simulate activities in the chamber. Four energy loads (400, 800, 1200, and 1900 watts) were used to simulate the presence of occupants in the chamber.; Results show that, under controlled experimental conditions, the difference between VAV/BPFS system and VAV system in reducing indoor air pollutant concentration (TVOC, PM and target VOCs) is statistically significant. Total energy consumption by the VAV/BPFS system was about 10 percent lower than that of the VAV system. We, therefore, recommend the VAV/BPFS system as a promising alternative to conventional VAV system because it is capable of reducing and maintaining good indoor air quality and conserving energy consumption. |
