Cost-effective air conditioning control considering comfort level and user location

Heating, ventilation, and air conditioning (HVAC) are important factors for a building energy management system (BEMS). Efficient control of the air conditioning (AC) is required to maintain both energy efficiency and human comfort. However, AC control systems are expensive to install in buildings. In this study, a cost-effective AC control system intended for a library is proposed; it is also applicable to other facilities such as offices and meeting spaces. This system uses seating sensors for maintaining both energy efficiency and human comfort. Conventional AC control systems generally use expensive motion sensors or vision sensors as well as temperature and humidity sensors to acquire information on both the location and the comfort of users and to provide location-based control to users. In order to reduce sensor-based cost, the proposed system uses low-cost pressure sensors and maintains both energy efficiency and the comfort level. For detecting seat occupancy and locations, low-cost pressure sensors and low-power communication nodes are attached to chairs and they transmit seating data to the database of a server. A programmable logic controller is used to control the proposed AC system according to the information stored in the database. The system is evaluated using a 10-day experiment conducted at a library in Kurihara City in Miyagi prefecture of Japan. The results of energy efficiency evaluation in this experiment show that the proposed system can reduce electricity consumption by 18.3%. Through measurement of the predicted mean vote values of users of the library, the proposed system is found to be capable of maintaining user comfort.