People's subjective response to any thermal environment is commonly investigated by using rating scales describing the degree of thermal sensation, comfort, and acceptability. Subsequent analyses of results collected in this way rely on the assumption that specific distances between verbal anchors placed on the scale exist and that relationships between verbal anchors from different dimensions that are assessed (e.g. thermal sensation and comfort) do not change. Another inherent assumption is that such scales are independent of the context in which they are used (climate zone, season, etc.). Despite their use worldwide, there is indication that contextual differences influence the way the scales are perceived and therefore question the reliability of the scales’ interpretation. To address this issue, a large international collaborative questionnaire study was conducted in 26 countries, using 21 different languages, which led to a dataset of 8225 questionnaires. Results, analysed by means of robust statistical techniques, revealed that only a subset of the responses are in accordance with the mentioned assumptions. Significant differences appeared between groups of participants in their perception of the scales, both in relation to distances of the anchors and relationships between scales. It was also found that respondents’ interpretations of scales changed with contextual factors, such as climate, season, and language. These findings highlight the need to carefully consider context-dependent factors in interpreting and reporting results from thermal comfort studies or post-occupancy evaluations, as well as to revisit the use of rating scales and the analysis methods used in thermal comfort studies to improve their reliability.

The adoption of air-conditioning as a cooling strategy in hot and humid climates is common practice. In such locations, the overcooling of buildings in a concern as this leads to the dissatisfaction of the occupants and unnecessary cooling energy consumption. In this regard, a field study was carried out in the Brazilian city of São Luis (hot and humid equatorial climate) to evaluate the preferred and most comfortable thermal conditions in this context. The investigation took place in air-conditioned and naturally-ventilated classrooms, in which the environmental parameters were measured concomitantly with the application of questionnaires to the undergraduate students for thermal assessment purposes. There was a difference between the preferred thermal sensations (noticeably the “slightly cool”) and the ones considered most comfortable/acceptable (“slightly cool” and “neutral”, equally), which reflected in the preferred and most comfortable temperatures. Thermal comfort in naturally-ventilated classrooms was limited due to high air temperatures and low air speeds. The best thermal conditions in air-conditioned classrooms were found to be between 23–24 °C standard effective temperature, and more than 20% of the students were uncomfortable below 22 °C because of excessive cold when clothing insulation values were close to 0.3 clo. The results also showed that indoor air temperatures can be set as high as 26 °C without impairing thermal comfort, which could aid attempts to minimize the cooling energy consumption in this year-round hot and humid climate.

Thermal discomfort is one of the main triggers for occupants’ interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses.