Suitable algorithms for calculating air renewal rate by pulsating air flow through a single large opening

Building ventilation of an enclosure with a single opening is affected not only by the steady mean effect of air pressures and temperatures around and within the building, but also by the turbulent nature of the wind. To improve understanding of the physical phenomena causing air exchange through a single opening, models to simulate the indoor pressure resulting from fluctuations of the wind-induced outdoor pressure are analysed and experimental requirements for model validation are discussed. The influence of the dimensions of the opening and the volume of the room on the time constant are discussed and the numerical constraints of the non-linear low-pass filter modelling for infiltration are highlighted. In particular the frequency limits for data logging or simulations are dependent on this time constant.

A method is proposed to avoid the oscillation of the simulated indoor pressure for the case of under-sampling which frequently occurs because of the limitation of data acquisition rates. The need for further work on this problem is discussed.