Supply air flowrate and supply air temperature can be varied to maintain the room tempera-ture setpoint according to the air temperature conditions outdoors and heating loads indoors. Increasing the supply air temperature and decreasing supply air flowrate can reduce energy consumption, however it causes insufficient air circulation and thus leads to low indoor air quality risk. Increasing the supply airflow will improve air circulation and mixing effective-ness within the room, but it will also increase energy consumption (Choa et. al., 2010), so there is a need to find an optimal correlation between air mixing effectiveness and energy ef-ficiency. The objective of this study was to identify the correlation between the minimum airflow and supply air temperature that would maintain a satisfactory thermal comfort in the human’s oc-cupancy zone when introducing warm air into the room. The study was conducted in the full-scale test chamber that represented a typical single office room. 24 air velocity and tempera-ture measuring probes were positioned in different levels and locations of human’s occupancy zone. Supply air diffuser prototype with a perforated faceplate was integrated into the ceiling and tested to see how the warm air is distributed within the test chamber. Numerous supply air temperature and flowrate variations were analysed during the study: to see, how does each variation affect the air distribution pattern; to find the best matching supply air temperature and flowrate balance to prevent the risk of air mass stratification and thus to ensure a good indoor air quality.