Existing studies have examined occupants’ adaptation and various parameters affecting thermal comfort of occupants in different buildings. However, there are limited studies that have examined occupants’ adaptation and design parameters in naturally ventilated sustainable buildings, especially structural timber buildings. As a result, this study considers a comparative analysis of occupants’ adaptation and examines various design parameters influencing behavioural actions of occupants in naturally ventilated structural timber buildings. The study evaluates indoor spaces of two dwelling units in each of the two sustainable timber case study buildings located in Western Europe. The research employed analysis of architectural design of the buildings, on-site measurements, and a thermal comfort survey. The parameters measured during the on-site survey include temperature and relative humidity at one hour intervals for twelve days during the summer period. The findings were compared with design parameters such as natural ventilation, size of opening, floor-to-ceiling height, and floor area of the spaces. The results showed more than 85% of the occupants in dwelling units with smaller floor area tend to adapt better to the thermal environment than those living in dwelling units with bigger floor area. It appears that at least 75% of the occupants in spaces with natural cross-ventilation tend to be more thermally satisfied than occupants in spaces with single-sided ventilation. The findings also revealed the risk of summertime overheating tends to be significantly reduced (p<0.05) when spaces have natural cross-ventilation, higher floor-to-ceiling height, and a larger floor area. Finally, the results showed the adaptation of occupants in naturally ventilated buildings and the ability to use control to adjust the thermal environment and reduce the overall annual energy consumption in sustainable buildings. Keywords: architectural design, comparative study, occupants’ adaptation, design parameters, behavioural actions, naturally ventilated sustainable timber building
