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• Real-time dynamic scenarios are investigated in the context of indoor environment. • The necessity of implementing CO 2 mass balance Equation has been established. • A demand-controlled ventilation (DCV) resetting strategy is proposed. • The proposed approach demonstrates significant energy savings potential. The ventilation component is one of the critical parts in an heating, ventilation and air-conditioning systems (HVAC) system and holds prime importance in ensuring operational efficacy and efficiency in terms of energy consumption and indoor environmental conditions. A true demand-based ventilation system with an economy air cycle not only offers reduced amounts of energy consumption but also can take part in a healthy indoor environment. This study provides true insight into the performance of a typical variable-air-volume air handling unit system under different operating conditions through a rigorous case study analysis in a real commercial building. To highlight pragmatic solutions to existing complexity within demand control ventilation strategies of the case building this study sets up real-time dynamic scenarios and investigates those scenarios in the context of indoor environment where both carbon dioxide (CO 2) and volatile organic compound (VOC) concentrations are linked. To predict and monitor the indoor air CO 2 concentration for the stated real time scenarios this study uses the mass balance equation for CO 2 concentration. This study demonstrates that integrating the CO 2 mass balance equation along with CO 2 sensor data into the building management control system not only assists in reducing energy consumption but also takes part in a healthy indoor environment. This study suggests including the mass balance equation for CO 2 concentration into the Australian ventilation standard AS 1668.2. [ABSTRACT FROM AUTHOR]

The appropriate application of advanced control strategies in Heating, Ventilation, and Air-conditioning (HVAC) systems is key to improving the energy efficiency of buildings. Significant advances have been made in the past decades on model development to provide better control over the energy consumption of system components while simultaneously ensuring a satisfactory indoor environment in terms of thermal comfort and indoor air quality. Yet it is an ongoing challenge to select and implement the best-suited modeling technique for improving the control strategy of HVAC systems. For the development of modeling research it is important that the building research community is informed about the role, application, merits, shortcomings and outcomes of different modeling techniques used in HVAC systems. Even though several review articles have been published on modeling techniques, the weaknesses and strengths of these modeling techniques, along with performances of developed models associated with research studies, have rarely been identified. This study presents a critical review of current modeling techniques used in HVAC systems regarding their applicability and ease of acceptance in practice and summarizes the strengths, weaknesses, applications and performance of these modeling techniques. Additionally, the performance and outcome of some of the developed models used in real world HVAC systems have been discussed. From the extensive critical review it is evident that almost every model has a major/minor shortcoming generated from assumptions, unmeasured disturbances or uncertainties in some system properties. This review aims at highlighting the shortcomings of existing application-based research on HVAC systems, and accordingly, recommendations are presented to improve the performance of building HVAC systems. [ABSTRACT FROM AUTHOR]