Analysis Methods for Natural and Hybrid Ventilation : a Critical Literature Review and Recent Developments

This paper is based on the results of Subtask B of the HybVent Project. It presents a critical review of the literature and recent developments in analysis methods for natural and hybrid ventilation in buildings. Ideally, analytical methods aimed at modelling hybrid ventilation systems should incorporate at least three key aspects i.e: the natural ventilation mode, the mechanical ventilation mode and the control strategy. Depending on the input parameters used within the control strategy, thermal comfort and indoor air quality related parameters may also need to be predicted. Available design methods for hybrid ventilation range from simple analytical and empirical methods through to multi-zone and computational fluid dynamics (CFD) techniques. When simulating the performance of hybrid ventilation throughout an entire year of operation, a fully integrated combined multi-zone and thermal model provides the most promising approach. In addition to detailing the available simulation techniques and their applications, this paper also reviews challenging issues such as the existence of multiple solutions to air flow analysis. It is suggested that more research and development is needed in the areas of multiple solutions and the uncontrolled divergence of transient multi-zone simulations.