A cost-effective operating strategy to reduce energy consumption in a HVAC system

Abstract

SUMMARYThe operation of the building heating, ventilating, and air conditioning (HVAC) system is a critical activity in terms of optimizing the building's energy consumption, ensuring the occupants' comfort, and preserving air quality. The performance of HVAC systems can be improved through optimized supervisory control strategies. Set points can be adjusted by the optimized supervisor to improve the operating efficiency. This paper presents a cost-effective building operating strategy to reduce energy costs associated with the operation of the HVAC system. The strategy determines the set points of local-loop controllers used in a multi-zone HVAC system. The controller set points include the supply air temperature, the supply duct static pressure, and the chilled water supply temperature. The variation of zone air temperatures around the set point is also considered. The strategy provides proper set points to controllers for minimum energy use while maintaining the required thermal comfort. The proposed technology is computationally simple and suitable for online implementation; it requires access to some data that are already measured and therefore available in most existing building energy management and control systems. The strategy is evaluated for a case study in an existing variable air volume system. The results show that the proposed strategy may be an excellent means of reducing utility costs associated with maintaining or improving indoor environmental conditions. It may reduce energy consumption by about 11% when compared with the actual strategy applied on the investigated existing system.

Cooling output optimization of an air handling unit

“…Therefore, minimizing the objective function (14) can push y 2 (t) and y 3 (t) towards their bounds. Then, the optimization model can be modified to (15 subject to :…”

“…5 demonstrates the fitness function values for different ratios of parent and offspring sizes. Note that the objective function at the vertical axis refers to the obj 1 in model (15), not the fitness values computed in Eqs. (16) and (17) at each generation.…”

“…Huang et al [9] introduced new functions for an energy management control system based on the dynamic model of a VAV-HVAC system and demonstrated energy reduction by using simulation. Nassif et al [15] developed a simple control strategy for minimum energy use which is suitable for online implementation. Using mathematical models of the cooling load and energy consuming devices, Lu et al [12] proposed a systematic approach to the optimization of the overall system energy consumption.…”

Optimized selection and operation of the combined chilled ceiling system and displacement ventilation

“…The objective function J operational represents the total energy consumption of the system during the optimization period due to the chiller supplying chilled water to both the DV cooling coil unit and the CC panel, fans, reheat, and water circuit pump. The optimization solver of Mossolly et al [1,31] will be used based on a genetic algorithm solver [32][33][34][35][36] that is able to identify the pay-off characteristics between daily energy cost and zone thermal discomfort and IAQ. The operation of the DV and CC system for each of the nine selected designs of subsystem combinations meeting the load will be optimized in response to the space load using a control strategy where both CC temperature and supply air conditions of temperature and flow rate can be simultaneously varied [1].…”

Application of terminal box optimization of single-duct air-handling units

“…Experimental results were shown that the residual ratio can be used to diagnose and accurately identify and detect multiple faults occurring in HVAC systems. Nassif and Moujaes [2] present a cost-effective building operating strategy to reduce energy costs associated with the operation of the HVAC system. The proposed strategy could reduce energy consumption by about 11% when compared with the actual strategy applied on the investigated existing system.…”