B032 IAQ sampling approach

A new indoor air quality sampling approach

Brief:

In order to maintain an acceptable indoor air quality (IAQ), policies, strategies and guidelines have been developed worldwide. In Hong Kong, the Environmental Protection Department (HKEPD) has launched an IAQ certification scheme to promote an acceptable IAQ in workplaces. It is believed that the longer the measurement time, the higher the accuracy and confidence level of the measurement can be achieved. Instead of sampling the pollutant concentration continuously in a period of the occupied time, this study proposes an alternative sampling scheme in which the average pollutant concentration is obtained from two short sampling periods in two sampling sessions. An indoor carbon dioxide (CO₂) concentration database for a one-year continuous measurement in a typical open-plan office building in Hong Kong is used to investigate the probable errors of the proposed scheme regarding the sampling period. The results show that the probable errors of the measured pollutant concentration deviated from a long-term average value are correlated with the required measurement time in different sampling schemes. At certain confidence levels, the required measurement time of the alternative sampling scheme was evaluated and compared with that of an 8-hour continuous one. It would offer a reduction of measurement effort up to 30%. It is recommended to specify the uncertainties and efforts of measurement in future codes, and to consider the sampling scheme in determining practical strategies for IAQ measurement.

Further Information:

Hui PS, Mui KW, Wong LT, 2006. A new indoor air quality sampling approach, Book of abstracts of the CIB W89 International Conference on Building Education and Research BEAR 2006-Construction Sustainability and Innovation, Ed. A Baldwin, E. Hui, F. Wong, Research Centre for Construction and Real Estate Economics and Research Centre for Construction Innovation, The Hong Kong Polytechnic University, pp. 99.