Peak Demand Limiting in New York Residential Housing: Automatic Air Conditioner Load Curtailment and Demand Limiting Using Wireless Mesh Communications

Daniel C. Harris, Association for Energy Affordability
Michael Bobker, CUNY Institute for Urban Systems

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Abstract

This paper presents the results of a project to demonstrate that fleet management of residential apartment air conditioning units can limit the electrical demand measured at a building master meter and achieve a cost savings without complaint from the residents. A building energy management system integrated a wireless mesh network and air conditioning (AC) unit controllers was installed in a 99-unit residential supportive housing building in New York City. A customized control algorithm was implemented to switch AC units in a temperature prioritized, intelligent, fashion to maintain predefined demand limits at the building master meter. The system also performed a load curtailment event test to simulate a response to an Independent Service Operator (ISO) curtailment event. The test description, results, and analysis are presented in this report. The energy management system operated over a complete billing period in the summer of 2005 to reduce the monthly peak demand by 46 kW, or 15% of projected peak, and yielded an estimated savings of $1150. A smaller avoidance in energy charge was also realized but not calculated. The load curtailment event test achieved a curtailment of 20kW, or 8% of building demand, over a two-hour period. The test results are utilized to discuss an economic strategy that trades off savings realized from operation under a daily demand limiting regime verses the potential revenue from responding to an ISO curtailment event.