Study of fresh air supply vent on indoor airflow and energy consumption in an enclosed space

Abstract

Majority of residents in many urban and suburban areas, especially in Southeast Asia, have seen a significant increase in time spent indoors over the past decade. It is not unusual for residents in these areas spending 70 - 90 % of their lives indoor either in home or office, and often in poorly ventilated rooms. These rooms are usually outfitted with ductless air conditioning (also known as room air conditioner) with no supply of fresh air for ventilation. The build-up of indoor air pollutants such as CO2, pathogens, and various volatile organic compounds in poorly ventilated room have been shown to be detrimental to both health and well-being its human occupants. This work aims to study the effect of introducing fresh air via a supply vent on the airflow within the room, while keeping track of the corresponding increase of energy consumption in the form of cooling capacity caused by ventilating warm fresh air into the room. To carry out this study, an air change per hour (ACH) of 10 supplied through different vent heights are simulated using a validated computational fluid dynamics model to investigate the behaviour of temperature, airflow, and energy consumption for five different vent-position cases. The simulation simulated case suggests that up to 27.7 % of a 1.0 horsepower (2.67 kW) air conditioner’s cooling capacity may be required to maintain the room at 22 °C with noticeable difference in airflow pattern within the room depending on the vent position. These findings will serve as a guideline for practical applications in designing ventilation systems in a small-to-medium enclosed space.