Sunlight enters a building through a window, transferring thermal energy to the room’s air and nearby surfaces. This heat transfer occurs through conduction (direct contact), radiation (electromagnetic waves), and convection (air movement). As the room air absorbs heat, it becomes warmer and rises, while cooler air flows in to replace it. This circulation distributes heat throughout the room, providing a comfortable environment. The process highlights the importance of heat transfer in buildings and the role of windows in passive solar design, harnessing natural sunlight to reduce heating needs.