Parametric analysis of the wind-driven ventilation potential of buildings with rectangular layout

Abstract

A method to evaluate the wind-driven ventilation potential of buildings is proposed and some schematic examples are given. Two indicators of such potential are put forward: the first concerning the pressure difference between spots (openings) on the facades and the second concerning the ratio between this pressure difference and a simplified measure of the pressure loss by the internal air flow. These indicators allow one to compare shapes and orientations and can help finding the most appropriate ones during a preliminary stage of the design of a naturally ventilated building. To present the proposal, a two-dimensional computational fluid dynamics parametric model of a schematic building is set, the parameters of which are the aspect ratio of the building's rectangular plan and the wind relative direction. The computational fluid dynamics simulations are supported by literature benchmarks and by qualitative experiments in a wind tunnel. Using this model, the pressure field is computed for 66 cases and their ventilation potentials are evaluated; some graphic outputs are then proposed for a preliminary understanding of the pressure field and of the resulting indicators. The optimal morphology given by such analyses is finally compared to that of some naturally ventilated existing buildings, including Iranian badgir towers. Practical application: This paper provides graphs to predict a building's potential for natural ventilation thereby enabling a designer to determine the wind-driven ventilation in a building and evaluate the structure, optimise its orientation, its aspect ratio and opening positions. These can be used, for example, in the evaluation of naturally ventilated multi-storey rectangular plan buildings (that might employ hyper-ventilation or night cooling) or to evaluate possible passive ventilation strategies for existing buildings. With the support of these graphs, which can be used as computationally inexpensive and fast decision tools, it is possible to simulate configurations, considering the parameters that most influence natural ventilation.