Provided according to one or more embodiments is a thermostat having a housing, the housing including a forward-facing surface, the thermostat comprising a passive infrared (PIR) motion sensor disposed inside the housing for sensing occupancy in the vicinity of the thermostat. The PIR motion sensor has a radiation receiving surface and is able to detect the lateral movement of an occupant in front of the forward-facing surface of the housing. The thermostat further comprises a grille member having one or more openings and included along the forward-facing surface of the housing, the grille member being placed over the radiation receiving surface of the PIR motion sensor. The grille member is configured and dimensioned to visually conceal and protect the PIR motion sensor disposed inside the housing, the visual concealment promoting a visually pleasing quality of the thermostat, while at the same time permitting the PIR motion sensor to effectively detect the lateral movement of the occupant. In one embodiment, the grille member openings are slit-like openings oriented along a substantially horizontal direction.