Abstract: Constant temperature and humidity chambers play a crucial role, predominantly in the textile testing sector. The reliability of test results hinges on the precision of the chamber's temperature and humidity controls. Based on the metrological characteristics of these chambers, a stratified approach was employed to measure temperature, humidity, and the implications of door operations. Findings reveal that the chamber's metrological attributes are satisfactory. For optimal monitoring of lab temperature and humidity fluctuations, it is recommended to position the hygrometer at the room's central point. A notable observation is that an 80-second door opening can lead to humidity excursions, necessitating a 2-minute period post-door closure to regain stability. This study provides insights that can guide periodic reviews and everyday operations of the constant temperature and humidity chambers.