A microprocessor-based energy management system at the University of Tennessee Space Institute

Because of rising energy costs and increasing energy use, a means of eliminating unnecessary energy consumption was needed at The University of Tennessee Space Institute. Such a means could not impair daily operations nor discomfort the occupants. Because of its centralized controls, the heating, ventilation and air conditioning system was selected as the primary target for these conservation measures. The heating and cooling system was separated into three categories: water circulating pumps, ventilation air handlers and front corridor air handlers. Each category was handled differently; however, all were scheduled for operation during occupancy rather than run continuously. Because of the overdesign of the air handlers, they were duty cycled to reduce their overall operation time. When moderate outside air temperatures prevailed, the heating and cooling could be terminated, using the outside air as the sole source of circulating air. During peak demand periods, the water circulating pumps were duty cycled to attempt to prevent an overrun of an established maximum demand limit and to reduce a high peak surcharge.

The energy management system employed the facilities of a VAX 11/780, a Cromemco Single Card Computer and peripheral devices including power demand and temperature sensors. Control of the heating and cooling system was effected by means of relays wired to the contactors of the control panel. The employment of these control measures has the potential of greatly reducing the peak demand surcharges and total energy costs.