Semi-outdoor workspace in the tropics: Exploring thermal comfort through field measurements and surveys

This study explores the viability of a semi-outdoor workspace in Singapore designed to promote natural ventilation as a sustainable alternative to traditional air-conditioned offices. Continuous physical measurements and voluntary occupant surveys were conducted over two months during the hottest season in Singapore to assess thermal comfort performance across different environmental settings under living workplace. Under natural ventilation, despite indoor temperatures averaging 30.4 °C and relative humidity around 70%, occupant comfort was largely maintained through elevated air speeds up to 1.0 m/s generated by ceiling fans. At high fan speed settings, occupant thermal satisfaction reached 68% while observed only 11% dissatisfaction rate, effectively minimizing discomfort related to excessive warmth sensation, insufficient airflow, and limited control of the environment. Compared to air-conditioning at a 28.0 °C setpoint with medium fan speed, which recorded the highest satisfaction among the air-conditioned settings, natural ventilation achieved comparable thermal satisfaction while reducing cooling energy consumption by approximately seven times. Additional energy use was recorded at 26.0 °C with fans settings, where two-fifth of occupants preferred a warmer environment, indicating potential overcooling even in tropical climates. Standard Effective Temperature (SET) analysis further identified an optimal comfort zone between 25.0 °C and 28.0 °C, supporting at least 80% thermal acceptability across a range of environmental conditions. This longitudinal field study in living testbed provides strong evidence that well-designed semi-outdoor workspaces can achieve high occupant satisfaction and substantial energy savings, offering a promising direction for more sustainable and resilient workplace designs in the tropics. • Thermal comfort assessment was conducted in a semi-outdoor workspace in tropics. • Elevated air speeds up to 1.0 m/s maintained comfort under natural ventilation. • High fan speed achieved 68% satisfaction and lowered dissatisfaction to 11%. • Natural ventilation reduced cooling energy use by approximately 7 to 17 times. • Optimal thermal comfort zone identified between 25.0 °C and 28.0 °C SET .