The indoor thermal environment holds a critical position within the realm of sustainable building practices, especially in the context of Kerala's warm and humid tropical climate. It plays a pivotal role in ensuring the comfort and well-being of occupants, making it a key consideration from the very inception of building design. This early emphasis on environmental concerns is essential for seamlessly integrating sustainability into the fabric of the building environment. The backdrop against which this emphasis on indoor thermal comfort occurs is the backdrop of global climate change, exemplified by the ongoing challenge of global warming. This phenomenon directly affects human comfort as a significant portion of our daily lives is spent indoors, engaged in various activities. As Kerala grapples with a growing urban population, the demand for additional housing, commercial spaces, offices, and amenities is on the rise. Modern-day occupants are increasingly cognizant of the pivotal role that sustainability plays in enhancing their overall quality of life. Central to this quality of life is the attainment of a favourable indoor thermal environment. This is especially true in residential settings, where the well-being and safety of residents are paramount. Global warming, with its rising temperatures and escalating greenhouse gas emissions, has wide-ranging repercussions for outdoor environments. In response, residential developments undergo transformations that alter urban climate dynamics. These changes are manifest in shifts in building materials, structural elements, and energy consumption patterns, all of which are driven by the economic activities of the human population. It is crucial to recognize that the indoor environment is intricately connected to external conditions. Therefore, understanding the factors that influence indoor thermal comfort is imperative when endeavouring to create a comfortable and health-promoting atmosphere within traditional Kerala courtyard houses. These factors encompass the microclimate of the site, including variables such as temperature, relative humidity, and wind patterns. These elements collectively contribute to the dynamic nature of the indoor thermal environment within these traditional tropical dwellings, underscoring the importance of considering them within the context of sustainability and comfort. Key Words: Vernacular Architecture, Thermal Comfort, Traditional Courtyard Houses, Climate Adaptation, Heritage.