Validity of Orifice equation and impact of building parameters on wind-induced natural ventilation rates with minute mean wind pressure difference

Natural ventilation is gaining more popularity in recent decades as a sustainable strategy to reduce energy consumption and improve indoor air quality. Due to variable turbulent characteristics, there is a lack of a practical guide that helps engineers accurately predict and maximize wind-induced ventilation rates. The current work intends to investigate the factors that influence the ventilation rates by focusing on cases that have a minor wind pressure coefficient difference. This paper presents an experimental study of single- and double-sided wind-induced ventilation mainly through two openings of a reduced scale building with three different building aspect ratios in a boundary-layer wind tunnel. A continuous dose method of tracer gas technique was used to evaluate the ventilation rate. Important factors that affect ventilation rates such as velocity in the vicinity of the wall where the opening is assumed to exist (expressed as “nearby velocity”) and surface wind pressure were measured. Flow visualization was also performed to help to understand the ventilation mechanism caused by turbulence. The experimental results showed that building aspect ratios of 1:2 and 1:3 generally led to higher ventilation rates than that of 1:1. Linear correlation between aperture separation and ventilation rates was reconfirmed regardless of openings symmetry. We noticed that the Orifice equation works well when the wind pressure coefficient difference is higher than 0.1. There is a positive correlation between the fluctuation of wind pressure coefficient and ventilation rates. The nearby velocity of the sealed model was uncorrelated with ventilation rates in this experiment