Guest Room Energy Management System

Hotel guest room energy management (GREM) systems are widely used throughout the world and the United States. The market for GREM has especially increased in the state of Nevada where guest room occupancy schedules vary at a high rate. Guests often leave their air conditioning equipment running during their absence. The GREM system determines the physical presence of guests by detecting infrared body heat. When a guest has left a room for a specified period, the system takes control from the normal thermostat and resets the room's temperature to energy conserving levels. Thus, installation of GREM control systems has been shown to reduce unnecessary energy consumption in unoccupied guest rooms. DNV GL conducted a GREM study at two hotels and casinos in Las Vegas Valley utilizing the INNCOM product. The primary objective of this assessment is to compare the energy use of GREM technology with existing technology, a conventional thermostat control. The selected sites were categorized by NV Energy service territories and types of HVAC equipment. Two types of fan coil units (FCU) were selected for this study - 2-pipe and 4-pipe systems. Energy uses of the FCUs were measured in equal numbers of rooms with conventional thermostat control and GREM control. A data acquisition system was installed to record important parameters, such as supply/return temperatures of airside and waterside, relative humidity and fan power with one-minute intervals for an entire year. These parameters were then analyzed to gain insight into the behavior of the FCU performance. Conclusions are determined by the estimated prescriptive energy savings resulting from controlling the FCU in unoccupied guest rooms. The results will be used to assess the prescriptive incentive program the utility offers to their customers. While Nevada's climatic data are considered in this study, the conclusions are generally more applicable in the desert southwest portion of the United States. © Copyright Association of Energy Engineers (AEE).