A sensor for sensing environmental characteristics of a space may include a visible light sensing circuit for recording an image of the space and a control circuit responsive to the visible light sensing circuit. The control circuit may detect an occupancy or vacancy condition in the space in response to the visible light sensing circuit, and measure a light level in the space in response to the visible light sensing circuit. The control circuit may also include a low-energy occupancy sensing circuit for detecting an occupancy condition in the space. The control circuit may disable the visible light sensing circuit when the space is vacant. The control circuit may detect an occupancy condition in the space in response to the low-energy occupancy sensing circuit and subsequently enable the visible light sensing circuit. The visible light sensor may be configured in a way that protects the privacy of the occupants of the space.