A demand limiting strategy for maximizing monthly cost savings of commercial buildings

Monthly peak demand costs usually contribute greatly to the monthly electricity bills of commercial buildings. Peak demand limiting control, which gained substantial attention recently, is an efficient way to reduce it. Most of previous studies either focus on the daily peak demand reduction without taking account the related energy rise, or explore the relationship between energy rise and demand reduction only on a daily basis. Unlike the previous studies, a new demand limiting control strategy is proposed in this paper in order to maximize the monthly cost saving. The new strategy is realized as follows. At first step, a proper monthly demand threshold is identified. At second step, a specific approach, named as proportional-integral-derivative (PID) algorithm, is implemented to restrain the daily peak demand to the given threshold by adjusting the indoor room temperature set-point. The extended pre-cooling duration is also estimated at this step based on the difference between the predicted daily peak demand and the identified threshold. The results of case studies show that the proposed strategy can substantially reduce the monthly electricity cost. (C) 2010 Elsevier B.V. All rights reserved.