Park Load Reduction by Preconditioning of Buildings at Night

Abstract

Cooling loads during the peak period can be reduced if a building is subcooled a few degrees below its normal thermostat setpoint during the preceding night. During the day, the thermostat must control the warmup in such a way that the stored energy is released when it brings maximum, benefit. This strategy exploits the heat capacity of the building itself; it can be implemented at low cost and without sacrifice in comfort. To evaluate the strategy for a given building and control the thermostat one needs to know the thermal behavior of the building. Building temperature, internal load and solar data are used to determine values of a small number of thermal parameters which characterize the building. Several thermostat control strategies. distinguished by their knowledge of the building dynamics, are described and simulated, both with a data-based dynamic model. Universal graphs for effective storage capacity and storage efficiency are developed. A simple economic analysis shows that subcooling is likely to be cost-effective for many commercial buildings with current electric rate schedules.