Natural ventilation air change rates considering atmospheric turbulence.

The estimate of actual air change rates considering atmospheric turbulence isintroduced. The starting point is the spectral description of turbulence - Kaimalspectrum was used in order to consider the height above ground. A set of syntheticwind velocity series are generated, out from a modified spectrum. The procedureconsiders an aerodynamic transfer function (a filter) where peculiar and cut-offfrequencies are determined by the general dimensions of the building and of theexternal openings, i. e., the turbulent scales of interest. For each opening isfurthermore possible to generate different but correlated time series, the correlationcoefficient being defined through the relative position of the openings, considering theappropriate scales of turbulence.A first set of results derived from a time step to step run of VENTIL - an integralmodel for NV estimates - using the synthetic wind velocity series shows that a fineaccurate estimate of the air change rate is now possible. The relation between rmsACH value and the turbulence intensity becomes evident. Further developments willlook upon a frequency analysis of these results.