01
Elevated CO₂
The dominant driver. Above 1200 ppm, most occupants describe the air as 'close' or 'stuffy' even when temperature and humidity are within comfort ranges.
02
Marginal warmth
Stuffiness perception rises sharply above 24°C. Many 'stuffy' complaints are partly thermal.
03
Low local air movement
Where supply diffusers throw stagnates over desks, occupants perceive the air as still even when bulk ventilation rates are adequate. Terminal rebalancing fixes it.