Energy saving has been explored over the past decades. Since most of the energy consumption in a building is from the air condition system, the air conditioners in a building are often controlled through a heating, ventilation, and air conditioning (HVAC) system. To control each HVAC unit individually, the locations of HVAC units are essential information. However, manual location identification requires significant labor for a large number of Internet of Things (IoT) devices deployed in a building. In this paper, we propose a Bluetooth low energy (BLE)-based HVAC unit localization method. We assume that a BLE module is attached to each HVAC unit, and then the locations of HVAC units can be estimated using the signal strength of the BLE module, which is observed by site survey of a worker. Our method requires a floor plan containing the physical locations of HVAC units and matches BLEs to the locations on the floor plan by estimation. The site survey can be carried out without visiting the entire site. Instead, the worker is required to follow several walking paths, which reduces the labor cost and time. We evaluated our method in a real office building with 26 BLEs on two floors. The results show that 70% of the BLEs were matched to their correct physical locations.