Assessment of thermal environment and thermal comfort in air traffic control towers

Ensuring thermal comfort in air traffic control towers (ATCTs) is paramount, given the exacting demands of air traffic control, which require heightened levels of concentration and vigilance. ATCTs feature extensive glazed surfaces, leading to significant solar gains and heat loss within the indoor environment. To maintain thermally comfortable conditions throughout the year, air conditioning systems are employed to regulate the indoor climate, adjusting for varying thermal load. However, achieving uniform and stable thermal conditions poses a challenge due to the dynamic thermal loads inherent in the environment. 
This paper aims to assess the thermal conditions and comfort levels within air traffic control towers across both winter and summer seasons. Furthermore, it seeks to evaluate the impact of glazing types and the air distribution systems on indoor thermal comfort. 
Eight field measurement campaigns were conducted in four ATCTs from February 2019 to March 2020. The ATCTs are all located in France, with three single-glazed towers and one double-glazed tower. In each tower, indoor air temperature and relative humidity were monitored at different heights and locations over one-week periods during winter and summer. Supply and extract air temperatures were also monitored, alongside measurements of terminal velocities. The occupants’ thermal comfort was assessed through targeted measurements of physical parameters related to thermal comfort and questionnaire surveys.  
The results of the physical measurements generally indicate acceptable comfort conditions in all four towers during both winter and summer periods, with occasional issues of local discomfort related to draughts in some cases. The questionnaire results yielded a mixed response, with overall acceptable comfort conditions in winter, juxtaposed with some discomfort issues in summer. The discomforts were found to be associated with operational deficiencies in the conditioning systems that have been identified. As a result, improvement avenues have been proposed to reduce discomfort.