Wind affects the radon entry rate from soil into buildings and the resulting indoor concentration. To investigate this phenomenon. we employ a previously tested three-dimensional numerical model of soil-gas flow around houses. a commercial computational fluid dynamics code. an established model for determining ventilation rates in the presence of wind. and new wind tunnel results for the ground-surface pressure field caused by wind. These tools and data, applied under steady-state conditions to a prototypical residential building, allow us to
- determine the complex soil-gas flow patterns that result from the presence of wind-generated ground-surface pressures,
- evaluate the effect of these flows on the radon concentration in the soil. and
- calculate the effect of wind on the radon entry rate and indoor concentration.
For a broad range of soil permeabilities. two wind speeds, and two wind directions, we quantify the "flushing" effect of wind on the radon in the soil surrounding a house, and the consequent sharp decrease in radon entry rates. Experimental measurements of the time-dependent radon concentration in soil gas beneath houses confirm the existence of wind-induced flushing. Comparisons are made to modeling predictions obtained while ignoring the effect of the wind-generated ground-surface pressures. These investigations lead to the conclusion that wind-generated ground-surface pressures play a significant role in determining radon entry rates into residential buildings.