An effective alerting strategy to facilitate occupants' perception of indoor air quality: By alarming concentration of indoor air pollution.

Previous studies have proven that it is hard for occupants to perceive concentration of indoor air pollution (IAP) and resulting indoor air quality (IAQ) on their own. Therefore, a method is needed to encourage them to turn their attention to actual IAP, in this context, alerting is thus suggested. However, previous studies pose limitations in that they failed to analyze the effects of alerting concentration of IAP on occupants' IAQ perception. To fill the research gap, this study sought to explore a proper strategy to help occupants have a clearer perception of IAQ. A one-month observational experiment was conducted on nine subjects under three scenarios with different alerting strategies. In addition, the visual distance estimation method was used to quantitatively analyze similar tendencies between the subject's perceived IAQ and concentration of IAP for each scenario. The experimental results confirmed that when an alerting notification was not sent, the occupants could not clearly perceive IAQ as the visual distance was the highest at 0.332. On the other hand, when the alerting notification whether the concentration of IAP exceeded the standard or not was sent, the occupants could perceive IAQ relatively clearly as the visual distance was reduced to 0.291 and 0.236. In conclusion, not only installing a monitoring device but also establishing proper alerting strategies on the concentration of IAP is essential to facilitate occupants' IAQ perception and protect occupants' health.

The effects of filters for an intelligent air pollutant control system considering natural ventilation and the occupants.

Experimental analysis was conducted on the indoor air pollutant concentration using natural ventilation and filters. The study targeted two office rooms each of which was occupied by four people, and with the same outdoor environments. A non-woven fabric filter (room A) and an electrostatic filter (room B) were installed on the window frame, and the indoor air pollutant concentration and indoor climate factors were monitored based on the number of occupants and the occupants' activities. The results are as follows: (i) when the number of occupants in each room increased from 0.03-0.06 to 1.53-1.63, room A showed a 60% average PM10 concentration increase while room B showed an opposite result (10% average PM10 concentration decrease), meaning the electrostatic filter's lower resistance to flow contributed to better ventilation and also decreased the influence of the occupants on the indoor air pollutant concentration. A low correlation (0.323-0.350) between the CO2 concentration and the occupants in room B also proved these results; (ii) while the average PM10 concentration in room A was 9 µg/m3 higher than that in room B, the average PM2.5 concentration in room A was higher by only 0.2 µg/m3, which showing that much of the generated or resuspended indoor particulate matter was PM10; and (iii) due to the more frequent heat transfer from outdoors to indoors, room B consumed 23% more heating energy. The results of this study are expected to be used as bases for the establishment of an appropriate management strategy that considers the indoor air pollutant concentration caused by the number of occupants and occupants' activities by combining natural ventilation and filters.