FIG. 1 shows 100 an embodiment of a system in which comfort level of a defined space may be modified based on factors determined by reference to personal electronic device signals. At 105 a defined space is shown. A “defined space” should be defined generously. It may refer to a single building, a collection of related buildings, buildings and space around them, an outside space such as a garden with irrigation, a portion of a building, such as a floor, a zone, a room, several rooms, etc. This defined space may have a building control system. The building control system may comprise a controller 110. The controller may comprise computer hardware 115 and memory 120, such that the controller can store and run computer programs. In some instances, the controller may also comprise a user input/output device, such as a computer monitor, a touch-screen, a thumb drive, a cd reader, and so on. The memory 120 may contain a user comfort preference 135. This preference may be used to determine a comfort model, or may be determined by a comfort model. The defines space also comprises at least one or more sensor(s) 125. The sensor(s) may help infer occupancy of the defined space, and infer other information to calculate a comfort level for occupants of the defined space 105. These sensors may be controlled by the controllers 110 which may be connected to the sensors using wired connections, wireless connections, or a combination of the two. These controllers may be able to control the sensors, read their sensor values, make decisions based on such sensor values, etc.