The fibers in the electret filter are permanently charged, so electrostatic forces act between the charged fibers and the aerosol. The aerosol capture mechanisms of these filters depend on a combination of the electrostatic mechanisms (dielectrophoretic and Coulombic) as well as the conventional mechanisms, including impaction, interception, diffusion and gravitationally settling.
Though many researches have investigated the filtration characteristics of the electret filters, few studies have demonstrated the comparison of influences of different parameters on the aerosol

That laboratory study was conducted to investigate the co-sorption effect of a dessicant rotor as an air-cleaning device and to show its practical value on improving perceived air quality. The air cleaning effect appears independent of air humidity. The observed air-cleaning effect of a dessicant rotor can also decrease energy consumption of HVAC systems that use desiccant cooling.

In this paper, the authors comment on the testing process of portable air cleaners whose test protocol is based on the measured decay rate of contaminant concentrations with the air cleaner operating compared with the measured decay rate when the air cleaner is turned off. The resulting metric, the clean air delivery rate (CADR) allows an intercomparison of performance among various air cleaners along with a comparison of air cleaner operation to other contaminant removal processes.

The performance of an air cleaner depends on the outdoor air change in the space where it serves. The results of that study reveal that when the outdoor air change rate of that space approaches the clean air delivery rate of an air cleaner, the efficiency of the air cleaner declines. Inversely, as the clean air delivery rate of an air cleaner exceeds the outdoor air change rate of the space it serves for by more than four times, the air change of that space has practically no effect on the air cleaners performance.

The objective of the present paper was to investigate the ability of activated carbon filters to protect office workers from the contaminants originally emitted outdoors. Models combining advection, sorption and diffusion in a porous medium were implemented in the Matlab/Simulink environment to simulate the dynamic behaviour of an integrated building/HVAC with activated-carbon filter system.

The overall performance of an air purifier in removing toal volatile organic compournds (TVOC) is presented in this paper. The air purifier has been connected with the air distribution system above the ceiling of the waiting area of the optometry clinic in Hong Kong polytechnic university.
The comparison between chamber test and field measurement indicates the effect of room ventilation on the effectiveness of air purifiers.

Photocatalytic oxidation (PCO) is a new approach that destroys chemically the pollutants instead of adsorbing them into a matrix. A high conversion of organic pollutants can be obtained with no production of ozone. The PCO unit disinfects the air and experimental studies indicate that a wide range of bacteria can be eliminated.

This paper reports the test results of a new photocatalytic oxidation air filter unit (PCO unit) that has been designed for aircraft cabin applications. The performances of the PCO technique have been measured in a single pass mode test rig to show its ability to decrease the amount of VOCs entering it, and in a multipass mode test rig to measure its ability to clean the air of a room polluted with the same VOCs. The results are promising but the development of that photocatalytic air filter must go on.

This paper is a sum up of the new ventilation requirements in Flemish region published in the Belgian "Moniteur" on June 17th 2005. The legal framework for the new regulation is given by the Decree on the Energy Performance and Indoor Climate, adopted by the Flemish Parliament ; the technical specifications are given in Execution Orders, approved by the Flemish Government.
There are two different sets of requirements :

In this paper, results of air leakage testing in newly constructed multi-unit residential buildings are presented, they show that individual apartments are relatively airtight. Energy use can be reduced, odor transfer between apartments can be prevented and occupant safety is enhanced during fire emergencies.