PERFORMANCE OF FAN-FILTER SYSTEMS IN NATURALLY VENTILATED UNIVERSITY TOWN RESIDENCES

Abstract

Haze has been a great concern to Singapore in the recent years, especially when the PSI value hit the highest value of 400 in June 2013. Singaporeans can expect to encounter haze during June to July annually. Because it is challenging or impossible to prevent haze from happening, it is crucial to evaluate the existing mitigation measures and develop an effective haze management plan. This dissertation focuses on the efficiency of two proposed fan-filter systems - (1) exhaust fan-filter system and (2) box fan-filter system - as an only source of providing ventilation in a completely enclosed naturally ventilated residential apartment in National University of Singapore during the haze period. The two types of fans, each attached to a HEPA filter with MERV 13 rating, are studied to evaluate their performance in providing sufficient ventilation to the apartment. Quantitative measurements are the main methodology used to assess the performance of fan-filter systems. There are total of 7 parameters measured – (1) the concentration of indoor and outdoor PM2.5 particles, (2) indoor air pollutants, (3) relative humidity, (4) operative temperature, (5) air change rate, (6) velocity of air exiting the fan unit and (7) the sound level generated by the two fan-filter units - are collected to assess the efficiency and suitability of the two proposed fan-filter systems. The study also includes the comparison of the measurements between an empty apartment, and when they are occupants. The findings in this study showed that both fan-filter systems are efficient in providing sufficient air flow to remove and dilute the indoor air pollutants in the air-tight apartment as the experimental values show a decreasing trend for the IAQ parameters. Additionally, the box fan-filter system is more efficient than the exhaust fan-filter system as the box-filter takes a shorter time to reduce the indoor concentration level of PM2.5 particles, achieving a steady-state as compared to the duration taken by the exhaust fan-filter system. As these fan-filter systems are recent proposal of haze management plan, future works are still required to assess the efficiency and suitability of the two fan-filter systems under haze conditions for natural ventilated residential buildings in Singapore.