Embodiments of methods and apparatus disclosed herein may employ depth, visual, or motions sensors to enable three-dimensional people counting and data mining to enable an energy saving heating, ventilation, and air conditioning (HVAC) control system. Head detection methods based on depth information may assist people counting in order to enable an accurate determination of room occupancy. A pattern of activities of room occupancy may be learned to predict the activity level of a building or its rooms, reducing energy usage and thereby providing a cost savings.
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