Available online at www.sciencedirect.com Building and Environment 39 (2004) 165 – 177 www.elsevier.com/locate/buildenv A study on the identication and quantication of sources of VOCs in 5 air-conditioned Singapore oce buildings M.S. Zuraimi * , K.W. Tham, S.C. Sekhar Department of Building, School of Design and Environment, National University of Singapore, SDE1, Level 3,4 Architecture Drive, Singapore 117566, Singapore Received 29 May 2003; received in revised form 6 August 2003; accepted 20 August 2003 Abstract Sources of VOCs were identied and quantied in ve tropical air-conditioned oce buildings in Singapore. A mass balanced model is applied to determine area-specic emission rates and to apportion the sources of VOCs into 3 broad categories of sources—building materials, ventilation systems and occupants and their activities. The highest contributor of TVOCs comes from the ventilation systems at 39.0%. This was followed by occupants and their activities at 37.3% and nally building materials at 23.7%. Ducted supply and return ventilation design has the lowest VOC area-specic emission rates as compared to buildings employing the open space above the false ceiling as return plenum. The TVOC area-specic emission rates from building materials and ventilation systems decreased from 6 to 12 months. However, some VOCs showed increased emission rates over the same period demonstrating sink eects which resulted in secondary emissions. ? 2003 Elsevier Ltd. All rights reserved. Keywords: VOCs; Sources; Area-specic emission rates; Building materials; Ventilation systems and occupants and their activities 1. Introduction Studies in temperate countries have documented that in- door concentrations of volatile organic compounds (VOCs) can be reduced by increasing the amount of outdoor air [1]. The concentration of the VOCs in the building how- ever is only a balance between the net emission within and what is removed by ventilation and sinks. Identica- tion of sources of potentially harmful or irritating VOCs and quantication of their emission rates provides the means of reducing levels of these compounds. Thus, pro- vision for minimum ventilation levels can be eectively implemented. This is especially critical in Singapore due to the fact that dilution by introduction of tropical hu- mid outside air is an expensive option [2]. Also, source control would be more eective and energy-ecient strategy. However, a major hindrance to implementing source control measures is that it is rst necessary to identify and quantify the signicant sources of VOCs in buildings. ∗ Corresponding author. Fax: +65-6775-5502. E-mail address: bdgzms@nus.edu.sg (M.S. Zuraimi). Although there have been many detailed studies of VOC emissions from chamber studies [3,4], there have been few in situ studies to determine actual contributions of vari- ous sources to the indoor environment [5,6]. At present, there is no information on the emission rates of VOCs for air-conditioned buildings in the tropics from dierent sources. Furthermore, the use of the models predicted by chamber studies has been deemed to only provide an ini- tial rough estimate of the VOC concentrations observed in real-life scenarios. This may be due to the fact that cham- ber tests may not reect actual building conditions where VOCs levels, temperatures, humidity and airows may uc- tuate [7]. This paper presents a study to identify and quantify the VOCs sources found in tropical air-conditioned buildings in Singapore. A mass balanced model is applied to deter- mine area-specic emission rates and to apportion the VOCs sources into 3 broad categories of sources—building mate- rials, ventilation systems and occupants and their activities. Application of these results may identify cost-eective mea- sures to reduce VOCs contamination in tropical indoor en- vironments and determine compliance with local regulatory standards. 0360-1323/$ - see front matter ? 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2003.08.013