B044 Office IAQ

How to achieve a good indoor air quality sampling in air-conditioned offices?

Brief:

An indoor air quality (IAQ) certification scheme for promoting workplace IAQ in Hong Kong has been launched in 2003. Feedbacks from the scheme implementation reported the selection of representative assessment parameters, required sampling period and locations needed to be justified with assessment accuracy and resources spent. This study reviews various IAQ sampling strategies regarding the trade-off among the assessment accuracy, the required number of representative parameters, the sampling period and the sampling locations; these aspect were examined against recent studies of long-term measurements, extensive spatial measurements and regional cross-sectional measurement of IAQ in typical air-conditioned offices of Hong Kong. In particular, a study of factor analysis of the 12 parameters measured in 422 air-conditioned offices of Hong Kong showed that a set of 3 parameters, namely carbon dioxide (CO2), respirable suspended particulates (RSP) and total volatile organic compounds (TVOC) would be selected as a ‘representative’ prescreening indicator for office IAQ. Besides, an assessment of only some ‘dominant’ contributors of unsatisfactory IAQ would compromise considerable reduction of measurement effort with quantifiable lost of measurement accuracy.

Furthermore, year-round measurements of common indoor air pollutants in typical air-conditioned offices showed that some sampling strategies could offer considerable reductions of sampling time and sampling point density at a limited lost of measurement accuracy. This paper illustrates examples of sampling time reduction by 30% at the same confidence level and sampling point density reduction by 50% at a decrease of 15% assessment accuracy. The results demonstrated possible flexibility in IAQ sampling strategies. This paper is a useful reference for various parties involved in developing practical strategies for IAQ sampling with feasible choices regarding measurement efforts and uncertainties.

Further information:

Hui PS, Mui KW, Wong LT, 2007. How to achieve a good indoor air quality sampling in air-conditioned offices? Proceedings of Zhejiang-Hong Kong Joint Symposium 2007 – Innovative Building Design and Technology-Challenges of Climate Change, HKIE/ASHRAE/CIBSE, 6-7 Jul, Hangzhou, China, pp. 30-37.