IMPACT OF VENTILATION SETTING ON CARBON DIOXIDE (CO2) ACCUMULATION IN A COMPACT CAR CABIN ENVIROMENT

Abstract

Indoor air quality (IAQ) in vehicle cabins is a growing concern, particularly due to rising carbon dioxide (CO₂) levels in enclosed environments during prolonged occupancy. This study investigates the behavior of CO₂ concentration over time under various ventilation and operational conditions in a compact vehicle cabin. The primary objective is to evaluate the impact of ventilation mode (recirculation vs. fresh air), vehicle status (static vs. running), and time of day (AM vs. PM) on CO₂ accumulation, referencing established standards such as ASHRAE and SAE. A total of eight experimental setups were conducted using a Perodua Axia, involving two to four passengers over 60-minute per sessions. CO₂ and temperature were monitored at ten-minute intervals using the GE Telaire® 7001 CO₂/Temperature Monitor. Key parameters such as fan speed and AC setting were held constant to ensure reliable comparisons. Meanwhile the number of occupants count increases from 2 passenger to 4 passenger by time. Data were analysed by plotting CO₂ concentration versus time to visually and statistically evaluate air quality trends. Results revealed that CO₂ levels increased significantly under static and recirculated air conditions, often surpassing the 1000 ppm threshold within 10–15 minutes, indicating potentially unsafe indoor air quality. In contrast, the use of fresh air ventilation in a running vehicle showed the most effective dilution of CO₂, maintaining levels well within safety guidelines. The study concludes that fresh air mode in a moving vehicle offers the best strategy for minimizing CO₂ buildup and ensuring occupant comfort and safety.