Shaving residential air-conditioner electricity peaks by intelligent use of the building thermal mass

The residential air-conditioning load is a significant component of electric utility peak demand, which typically occurs on very hot summer afternoons. Efforts by utilities to shave or shift air-conditioning demand to off-peak periods in the day have been spurred by low-cost electronics and include such strategies as direct-load control and price-induced local control by homeowners. We propose alternative practical strategies of peak shaving that use the opportunities offered by modern electronics as well as a more intelligent use of the thermal mass storage inherent in the structure and furnishings of the house. Using the framework of a simplified electrical analogue, we predict the thermal performance of the residence when the air-conditioner is switched off and illustrate the validity of such simplified estimates with monitored data from an actual residence. Finally, we discuss practical aspects related to the implementation of these strategies, particularly as to what is needed in terms of electronic sophistication of the thermostat.