Supply airflow rate and supply air temperature can be varied to maintain the room temperature setpoint according to the air temperature conditions outdoors and heating loads indoors. Increasing the supply air temperature and decreasing supply airflow rate can reduce energy consumption. However, it causes insufficient air circulation, leading to risk of low indoor air quality. Increasing the supply airflow will improve air circulation and mixing effectiveness within the room, but it will also increase energy consumption, so there is a need to find an optimal correlation between air mixing effectiveness and energy efficiency.