1. A method of monitoring a building comprising: taking a video within a location in the building with a video sensor, the video comprising a plurality of frames, each frame including image data; for each frame, receiving depth data associated with the image data, the depth data corresponding to one or more distances from the video sensor to features represented by the image data; analyzing the image data and depth data to detect and classify one or more objects depicted in the video, classification of the one or more objects comprising determining whether at least some of the one or more objects are people; counting a number of people based on the analyzing of the image data and the depth data; and controlling a system of the building in response to the number of people counted.