Sensory Pollution from Bag Filters, Carbon Filters and Combinations

Used ventilation filters are a major source of sensory pollutants in air handling systems. The objective of the present study was to evaluate the net effect that different combinations of filters had on perceived air quality after 5 months of continuous filtration of outdoor suburban air. A panel of 32 subjects assessed different sets of used filters and identical sets consisting of new filters. Additionally, filter weights and pressure drops were measured at the beginning and end of the operation period. The filter sets included single EU5 and EU7 fiberglass filters, an EU7 filter protected by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC. Furthermore, its pressure drop changed very little during the 5 months of service, and it had the added benefit of removing a large fraction of ozone from the airstream. If similar results are obtained over a wider variety of soiling conditions, such filters may be a viable solution to a long recognized problem

Perceived indoor environment in social housing with different ventilation principles

The need for renovation and energy retrofitting of Danish social housing from the 1960s and 1970s is substantial. Such energy retrofits often include the installation of mechanical ventilation systems with heat recovery to fulfil the current standards for energy efficiency. These systems typically ensure a more constant and higher ventilation rate than previous systems. Therefore, there is potential for residents to perceive a higher air quality and a reduction in problems due to condensation on cold surfaces and mould growth after retrofits. The purpose of the present study was to evaluate if this potential is realised for residents in social housing complexes. A questionnaire survey was performed among residents in dwellings with ventilation categorised within one of the five ventilation principles: natural ventilation, bathroom fan, exhaust fans in the kitchen and bath, decentralized balanced mechanical ventilation and centralized balanced mechanical ventilation. Compared with residents without balanced mechanical ventilation, residents having such systems perceived less often problems with unpleasant odour from their own apartment and less visible mould, but more often perceived the air as dry. Residents with decentralized mechanical ventilation tended to experience more often problems with noise from their ventilation system. However, results show that nuisance are avoidable with correctly designed decentralized ventilation.publishedVersio