The aim of this study, part of the RENOPTIM project, is to challenge existing comfort and thermal stress indicators, and to bring discomfort thresholds into line with how the French population feels during summer and hot weather. The data collected during the experimental campaign on thermal comfort will enable to validate and refine the thresholds defined in the regulation RE2020. In this study, 76 dwellings in three regions of mainland France were instrumented for four months in the summer of 2023. Occupants were asked to respond to a questionnaire about their thermal sensation, comfort, acceptability and satisfaction of their thermal environment. This questionnaire was filled in by participants via a “comfort box”, enabling responses to be entered via a touch screen. This box also measures two key parameters of the thermal environment: air temperature and relative humidity. It was placed in the main room of the dwelling so as to be easily accessible by the occupant and to provide a representative measure of perceived comfort. By crossing indoor temperatures and comfort ratings, it was possible to establish thresholds for several levels of discomfort, thermal sensation, acceptability and satisfaction. Once the comfort scales were constructed, it was possible to project the time periods of comfort and discomfort on the entire sample of dwellings and the whole duration of the study. The discomfort durations predicted from measurements were compared with the DH regulatory indicator.