Numerous ground-coupled air systems have been constructed in combination with heat recovery units in mechanically ventilated buildings in Switzerland. The objective of this study was to investigate the microbial content within these ventilation systems and to monitor the quality of the air supply. The concentrations and the types of microorganisms in the outdoor air, in the air of the pipes and in the supply air of twelve groundcoupled air systems were determined. In addition, three buildings were examined four times a year to cover seasonal changes.
Particle loss augmentation in turbulent flow was studied experimentally. Experiments were performed in a I SO mm square ventilation duct. Small tracer particles of size ranging from 0.7-7.l μ.m were used to study deposition enhancement with streamwise-periodic disturbances mounted on one of the principal walls, under turbulent flow. A new and highly sensitive analytical technique was adopted to determine the spatial mass flux along the ribbed duct. On some surfaces, particle deposition enhancement as much as seven times higher than on .smooth surfaces was observed.
The connection between health and cleanliness is, for most people, a matter of common sense. Office workers report higher rates of discomfort when they perceive a dirty, dusty environment. Research, not surprisingly, shows that certain cleaning methods are effective in reducing dust on surfaces and in reducing the levels of indoor air contaminants. Yet some cleaning practices, like the use of improperly diluted cleaning solutions, are themselves significant threats to good IAQ. As with everything else, there are right and wrong ways to clean.
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