Thermal comfort is an essential parameter for the well-being of occupants in buildings. This paper aims to analyze the thermal comfort of a 400-person capacity-art center auditorium at Universitas Indonesia. The physical parameters evaluated include temperature and humidity according to both ASHRAE-55-2010 and National SNI 03-6572-2001 standards on thermal comfort conditions. The auditorium air conditioning system utilized a 56-ton refrigeration air-cooled chiller with natural refrigerant R290 and was equipped with both refrigerant and watersides sensors and data acquisitions. A simulation of the airflow and temperature distribution of the auditorium was also developed. Experimental measurement using automatic data loggers was performed on-air drybulb temperature and humidity inside the auditorium during events with empty and full-capacity audiences. The results are compared to the simulation and standards. The simulations resulted in an average temperature difference of 12.7% compared to the temperature obtained from experimental data. According to the standards provided, the auditorium's chiller system can maintain thermal comfort with an average cooling load of 52.4% at COP of 4.34. The result shows that the auditorium can sustain a thermally comfortable indoor environment with an average of about an hour of thermal recovery time. The auditorium air conditioning system also shows that using an environmentally friendly refrigerant R290 with very low GWP refrigerant for building air conditioning systems can provide thermal comfort and energy-efficient solutions.