B057 Office IAQ assessment

On sampling period and sampling point density of indoor air quality assessment for Hong Kong offices

Brief:

Maintaining acceptable indoor air quality (IAQ) has become a public issue of Hong Kong, policymakers have had developed strategies to address the performance of it. An 8-hour continuous measurement with sampling point density of 500m² recommended by the HKEPD has been widely adopted in local IAQ assessments, though, technical difficulties were faced when implementing it and the uncertainty of probable measurement errors associated hindered the choice of alternative measurement protocol. This study proposes alternatives in sampling the air pollutant exposure level with various sampling periods and sampling point densities at specified assessment uncertainties. In particular, a database of long term CO₂ exposure level determined from a 1-year measure result at 17 locations in an in-use air-conditioned office of Hong Kong was used as a reference, to evaluate the probable errors of sampling approaches with various sampling periods and sampling point densities. The results showed that the confidence level of the current HKEPD sampling scheme was 41%. At this acceptable confidence level, alternative sampling schemes at a combination of sampling periods and sampling point densities were proposed. Sampling point density and time period regarding the audited parameters must be determined at an acceptable uncertainty. This study suggests flexibility of sampling in IAQ assessment, and would be a useful source of information in developing sampling approaches of exposure levels for IAQ audit.

Further Information:

Hui PS, Wong LT, Mui KW, 2008. On sampling period and sampling point density of indoor air quality assessment for Hong Kong offices, 2^nd Faculty Postgraduate Research Conference 2008, 19 Jan 2008, Faculty of Construction and Land Use, The Hong Kong Polytechnic University, pp. 106-111.