A system and method are disclosed for using gas detection techniques to determine if a room is vacant or occupied, and to activate, dim or deactivate lighting based on a detected occupancy status. The system and method may monitor a concentration of a first gas using a gas sensor such as a CO2 sensor. The space may also be monitored using second and third sensors, and a vacancy status of the space may be based on the concentration of the first gas and information from the second and third sensors. The second and third sensors can be passive infrared sensors, ultrasonic sensors, gas sensors, microwave sensors, audio sensors, or video sensors. An electrical load associated with the space may be controlled based on the determined occupancy/vacancy status. Other embodiments are described and claimed.