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The transportation of ambient particulate matter (PM) from outdoor air into the inlet of a mechanical building ventilation system is poorly understood. No studies have examined the effect commonly used commercial air handling unit (AHU) inlet designs have upon the migration of PM from the ambient environment into the building ventilation system, and implications of this on energy consumption and indoor air quality (IAQ). Through the numerical analysis of commercial AHU inlets, the differences in concentration of PM in ambient air and that within AHUs were determined, more commonly referred to as Aspiration Efficiency (AE %). A 20-50% difference in particle concentrations between ambient air and the in-AHU concentration was observed between forward and rear-facing AHUs relative to ambient wind direction and speed, and at the maximum ventilation flow rate. Furthermore, a decrease in the ventilation flow rates resulted in a significant reduction in PM concentrations entering the rear-facing AHU. Increasing the Stoke number led to lower AE as a continuous decrease was observed for both rear-facing inlets. The findings of this paper show that AHU inlet design has significant implications on IAQ and building energy consumption, and scope exists to design these inlets to impact both aspects positively.

The evidence of health benefits of particle filtration in homes and commercial buildings is reviewed. Prior reviews of papers published before 2000 are summarized. The results of 16 more recent intervention studies are compiled and analyzed. Also reviewed are four studies that modeled health benefits of using filtration to reduce indoor exposures to particles from outdoors. Prior reviews generally concluded that particle filtration is, at best, a source of small improvements in allergy and asthma health effects; however, many early studies had weak designs. A majority of recent intervention studies employed strong designs and more of these studies report statistically significant improvements in health symptoms or objective health outcomes, particularly for subjects with allergies or asthma. The percentage improvement in health outcomes is typically modest, e.g., 7percent to 25percent. Delivery of filtered air to the breathing zone of sleeping allergic or asthmatic persons may be more consistently effective in improving health than room air filtration. Notable are two studies that report statistically significant improvements, with filtration, in markers that predict future adverse coronary events. From modeling, the largest potential benefits of indoor particle filtration may be reductions in morbidity and mortality from reducing indoor exposures to particles from outdoor air.

International audience; On modern airliners, cabin air pressurization, heating and renewal is achieved using air supplied from the gas turbine engines during flight. This air intake impairs the motors yield and needs to be conditioned, leading to energy overconsumption. Recent advances in thermal management enable aircraft manufacturers to reduce further the intake airflow needed to maintain cabin temperature at high altitude. Nevertheless, for lower air renewal rates, an appropriate air filtration system will be needed to maintain acceptable air quality in the cabin. In this context, Clean Sky 2 Joint Undertaking (CS2JU) project EC2S (Environment Control Secondary System) aims at developing an integrated filtration system to be implemented in existing cabin air management systems (so called Environmental Control System-ECS). The EC2S unit will include three filtration units addressing separately Volatile Organic Compounds (VOCs), CO2 and Particulate Matter (PM). Circulated air in the ECS is conventionally filtered on pleated HEPA filters that generate substantial pressure drop. Since the EC2S VOCs and CO2 filtration units would generate additional pressure drop in the ECS system, electrostatic precipitation is foreseen as a low flow resistance alternative for PM removal. This paper reports the development and performance assessment of a two-stage electrostatic precipitator (ESP) designed for aircraft recirculated air filtration. The ESP prototype presents single pass high particle collection rates (i.e. over 90% for airborne particles with an aerodynamic diameter of 0.5 μm or larger), low pressure drop (i.e. 4 Pa at nominal flowrate) and a limited ozone generation rate (i.e. below 8 mg.h-1).