B072 Office IAQ screening

Screening analysis of unsatisfactory airborne bacteria level in air-conditioned offices of Hong Kong

Brief:

Adjustment of the indoor air temperature and relative humidity set points is deemed as an efficient energy conservation measure in many air-conditioned offices in the subtropics, with the consequences of probable thermal comfort complaints only. This study investigates the presumptive detection of unrecognized indoor air quality (IAQ) problems of an indoor environment from the perspective of the probable airborne bacteria level exceeding certain limits in various thermal environments at the measured air temperature and relative humidity (RH). In particular, the measured air temperature and relative humidity were used as screening parameters to determine the likelihood ratios of unsatisfactory IAQ due to excessive airborne bacteria count (ABC) in air-conditioned offices. The feasibility of the screening process is tested with a cross-sectional study of ABC at a thermal environment of 422 air-conditioned offices in Hong Kong. The results showed that at RH of 50%, the likelihood ratios of the unsatisfactory IAQ were 0.5 and 2 corresponding to the air temperatures of 24.5°C and 26.2°C; and at RH of 60%, the corresponding air temperatures were 22.4°C and 24°C respectively. This screening test would be a useful tool for policymakers, building owners and professionals to identify those offices with probable IAQ problems and to make better decisions on resources for any IAQ surveillance programmes.

Further Information:

Mui KW, Wong LT, Chan WY, 2008. Screening analysis of unsatisfactory airborne bacteria level in air-conditioned offices of Hong Kong, Joint Symposium 2008 on Shaping our Future Environment, 18 November, Kowloon Shangri-la Hotel, Hong Kong, pp. 31-38.