Abstract Thermostatically controlled loads in commercial buildings are usually ruled by set points indicated by well-established international standards like EN 15251. These thresholds set the acceptable comfort ranges based on several parameters such as activity level, climatic conditions and building orientation. However, there are so many aspects which can affect the occupant perception of comfort ranging from physical and mental aspects to cultural aspects while only few of them are clearly measurable. This paper presents a methodology for the simultaneous subjective and objective evaluation of thermal comfort in commercial buildings. The methodology is based on the intermediate protocol level for the evaluation of thermal comfort as suggested by ASHRAE’s Performance Measurement Protocols for Commercial Buildings. It is applied in the office spaces of the Loccioni Leaf Lab, located in the province of Ancona, Italy, during the summer period. The study is utilized for the identification of serious thermal comfort issues but also for the determination of the preferred comfort conditions in the Leaf Lab office spaces.