Investigating the behaviour of ASHRAE, Bedford, and Nicol thermal scales when translated into the Arabic language

With the global spread of thermal comfort studies, thermal scales are translated into different languages to adapt local context in which the studies are applied. However, translating thermal comfort scales does not maintain behaviour that is associated with their original English versions. Behaviour differences include irregular categories' width, asymmetry, and deviation of the middle category centre from the centre of the thermal continuum. These differences have a negative influence on the results of thermal comfort studies and their accuracy. Applying the successive categories method, this paper explores the change in ASHRAE, Bedford, and Nicol scales' behaviour when translated into the Arabic language. The translated scales were integrated into questionnaires distributed among female high school students in Muscat, the capital city of Oman, as part of a larger survey that lasted for a whole year. The findings revealed the deviation of the translated scales from the original assumptions of the English versions. This included categories' irregular widths and asymmetry in addition to the deviation of the centre of the middle categories from the centre of the thermal continuum. Besides, it was found that both ASHRAE and Bedford scales covered different ranges on the thermal continuum, which questions their assumed equivalence. Based on these findings, the accuracy of the thermal comfort analysis is negatively affected. Considering the sensitivity of scales' behaviour to the used phrases, further explorations implementing the terms examined in this study are recommended.