The optimized scheduling of a sanitary water heating system for commercial high rise apartment buildings

Abstract

The installation of energy efficient water heaters in the residential and commercial sectors of South Africa have drawn much attention for more than a decade due to the energy crisis in South Africa. Most of the installations are however focused on the energy savings potential of the heating equipment rather than the efficient control of the water heating systems. Two high rise apartment buildings with heat pump water heaters as the primary installed heating equipment, have been evaluated to determine the actual hot water consumption of the respective buildings. The consumption profiles are used as input for the hot water scheduler, presented in this paper, which optimizes the control of a predefined water heating system. The scheduler can be utilized to effectively determine the required size of water heating equipment along with an optimum control solution for the heat pump units. By scheduling the operational hours of the heat pump units in combination with the available hot water storage capacity and the time-of-use tariff structure of the South African electrical utility, Eskom, additional energy savings can be achieved. Potential simulated energy savings of up to 55% are possible by utilizing the hot water scheduler based on the actual measured hot water consumption of the two high rise apartment buildings.