A method of making a thermal comfort estimation of one or more human occupants in a built space in real-time is presented. The method employs one or more thermographic cameras and one or more red, green, and blue depth (RGB-D) sensors. The method has several steps. In an example, the method involves capturing thermal images of the human occupant(s) via the thermographic camera(s) and capturing RGB-D images of the human occupant(s) via the RGB-D camera(s). The method further involves extracting facial skin temperatures of the human occupant(s) using the captured thermal images and using the captured RGB-D images. And the method involves estimating the thermal comfort of the human occupant(s) using the extracted facial skin temperatures.