Energy Efficiency and the Control and Simulation of VAV Systems

Paul Bannister, Exergy Australia Pty Ltd

Keywords

Abstract

Variable air volume (VAV) systems are one of the most common air-conditioning system types for larger buildings in warm temperate climates and are likely to remain so for some time. However, VAV systems are heavily dependent upon control for their efficient operation and are particularly prone to system-wide failure as a result of the malfunction of individual components in the field.

In this paper the key control methodologies for VAV systems are discussed from the perspective of energy efficiency, robustness to common mechanical failures and long term manageability in a realistic operating environment. Key issues examined include fan control, supply air temperature control, VAV terminal control and the coordination of terminal and AHU actions to minimise simultaneous heating and cooling.

Unfortunately, many of the key algorithms used in VAV system control cannot be properly modelled in leading simulation packages, leaving most control optimisation to be assessed on the basis of intuition rather than analysis. This paper concludes with a list of key features of VAV control that should be included within simulation packages to enable the complete and accurate assessment of this important air conditioning system type.