Field Evaluation of Hotel/Motel Through-the-Wall HVAC Systems Supervisory Controller

Several potential energy-savings devices are available for through-the-wall HVAC (heating, ventilation, and air-conditioning) systems but independent test data quantifying their savings are sparse. This field evaluation and demonstration study quantifies the potential energy savings and assesses the impacts on occupants and staff of using a supervisory HVAC controller in the lodging industry. The supervisory controller operates according to the occupancy status of each room in a hotel or motel. The controller is a plug-in device installed between a wall outlet and the room HVAC unit. Preliminary tests in laboratory simulated environmental conditions suggest that energy savings ranging from 50% to 80% are possible in unoccupied lodging rooms employing the controller (Fisher, 1999). The field study objective was to quantify and verify these estimates and to identify impacts on occupant comfort. The controller was developed as a tool for reducing energy consumption and lowering operating costs in the lodging industry. This paper describes results from a field evaluation of the performance of a supervisory HVAC controller. During the test period, the uncontrolled rooms HVAC energy consumption averaged 2632.2 kWh monthly while the controlled rooms HVACs consume an averaged 1684.6 kWh, which equates to the uncontrolled rooms HVAC consuming an averaged of 947.6 kWh (56.3%) more energy than the units in the controlled room monthly. Due to intermittent inoperability of the controllers and other energy loads (controllers controlled approximately 50% of the hotel’s conditioned space), comparison analysis of the energy cost over a three-year period for the entire hotel does not reveal any discrete savings during the test period over prior years.