A COMPARATIVE STUDY OF THERMAL COMFORT AND IAQ IN NV/MV AND AIR-CONDITIONED CLASSROOMS IN SECONDARY SCHOOLS IN THE TROPICS

Abstract

In the tropical climate in Singapore, air conditioning has been the common solution to solve the indoor thermal comfort issues. Some secondary schools have started to install air-conditioners in the classrooms. Thus, the aim of this study is to compare the indoor air quality (IAQ) and thermal comfort in a natural ventilated and air-conditioned classroom from both the objective and subjective approach.

In this study, analysis has been done between two schools with different classroom environment on a typical sunny day. These results should serve the purpose to help schools to understand the advantages and disadvantages of air-conditioning the classrooms. The objective measurement includes measurement of carbon dioxide, carbon monoxide, operative temperature, relative humidity, Total Volatile Organic Compounds (TVOC), particulate matters, air velocity and total mould and bacterial counts. Surveys are conducted to gain the students perceptions on their classroom environment and to determine the presence of any sick building syndrome during lessons.

The experimental results indicated that the overall IAQ in the natural ventilated classroom is better. However, the operative temperature, relative humidity, air velocity and total mould and bacterial counts failed to meet the recommended level.

On the overall, the indoor air quality and thermal comfort level in the air-conditioned classroom is better than the natural ventilated classroom, particularly the students’ perception and its temperature and relative humidity level. However, the accumulation of carbon dioxide in the air-conditioned classroom is above the recommended level. This can be harmful to the students in the long run and may cause the students to feel lethargic in class.

In conclusion, both types of classroom have its merits in terms of IAQ. However, the air-conditioned classroom would indeed provide a more thermally acceptable environment. Recommendations are also made to improve the classrooms environment.