This paper deals with two general approaches used to determine multizone air flow by tracer gas experiments : a tracer gas decay model and a simultaneous release of n different tracer gases in n zones (n x n approach) . The results show a suitable agreement between the model and measurements made, at work-time, in a 3-store building equipped with an hybrid ventilation system.
The deposit of particles on ceilings close to ventilation outlets is mainly caused by the features of mixed ventilation, turbulence and induction. This study aims at solving that annoying problem of particle deposition, for the ventilation industry. The development of a clean outlet is eased thanks to a new experimental approach using an optical technique (in so far as the experimental technique and the CFD calculations are too inefficient).
The paper describes the test procedure and sums up the criteria for the air handling components and systems defined in the Finnish guideline for ventilation equipment Test methods, such as a measuring method of mineral fibres released into airflow, and a method for measuring the odour threshold of processing oils have been added to the guideline.The experience from the labeling system has been very positive .
The study was carried out on 6 subjects. Each one is seated at a desk with a mounted PVS. During the experiment the room air temperature was controlled at 28C and the personalized air temperature was 25C. Several fluctuations were tested, air movement with a frequency of 0.2 Hz was preferred to 0.1 Hz and 0.3 HZThe subjects had a preference for a lower mean air velocity but were more distracted when air movement fluctuated (0,2 Hz) than when it was constant.
Indoor air cleaners are available on the market but a lot of them are not tested and their performances are not known. The main objective of our study was to develop a laboratory test method which allows to determine the life span of indoor air cleaners. Loading of the device is carried out with tobacco smoke which is an air pollutant that reflects real conditions. Fractional efficiency and air flow rate of the device are measured at the initial stage (clean device) and step by step as the device becomes loaded.
The National Institute for Occupational Safety and Health (NIOSH) has undertaken a long-term performance test of heating, ventilation, and air-conditioning (HVAC) system filters. This testing is being conducted at the NIOSH facility in Morgantown, WV in an air handling unit (AHU) that services the animal quarters. The six-pocket bag filters in this AHU have been replaced with higher efficiency mini-pleat V-Bank filters and have been monitored monthly for filtration efficiency.
Air quality begins with good engineering air handling system (HVAC) controls. Air handler filters should remove the major particulate matter from incoming ambient air. A study of various NIOSH air handler bag filters was conducted to determine their filter efficiency against submicrometer particles (0.03-0.4 micrometers), since submicrometer particles are the most penetrating. Aerosol penetration measurements show an extremely large range of filter efficiency.
Several indoor air biofilters containing higher plants, mosses and microbes have been incorporated into functional offices, where they are a supplemental means of controlling indoor air quality through the removal of volatile organic compounds. In theory a rich microbial community indoors may in fact lower air quality through the production of microbial agents such as spores or aerial bacteria. Questions have arisen regarding the impact of an indoor air biofilter on ambient spore concentrations including the pathogen Legionella pneumophilia.
Maintenance workers expressed concern of a potential health hazard due to a strong odor from used ventilation filters during routine maintenance at a research facility. This prompted a thorough examination of the physical and chemical nature of the filters and collected particulate matter. Light and electron microscopy indicated a predominance of opaque small particles, mostly in the submicrometer range. Many were agglomerations of smaller, roughly spherical subunits, consistent with combustion aerosol.
Indoor air quality differences were investigated among five schools with and five schools without active humidity control systems. The active humidity systems provided approximately 15 cfm/person of ventilation air, while the schools without the active humidity control systems averaged less than five cfm/person. The space humidity levels in varying widely without active humidity control, and rose to unacceptable levels during summer shut-down periods.
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