Present international standard for thermal comfort such as ASHRAE Standard 55 and ISO 7730 were developed to serve as a guideline for moderate thermal environments e.g. mechanically air- conditioned spaces [CEN ISO 1995]. Recent thermal comfort studies had reported that some discrepancies were observed in its application for Naturally Ventilated (NV) buildings in hot and humid tropical climate [Feriadi et.al 2003]. The standard failed to take into considerations tolerance and different perception of thermal comfort from different environmental setting. In this study, fuzzy logic approach is used to model an appropriate Thermal Comfort (TC) standard for tropical naturally ventilated houses. The complexities of the human cognitive process and the vagueness of linguistic expression are considered. Fuzzy logic is used as a mathematical model to allow representation of human decision and evaluation processes in algorithmic form. A detail exposition of the application which combined the linguistic approach to the optimization under multiple thermal condition criteria is presented.