Variation of radon entry rate into two detached houses

The influence of various factors on the concentration of indoor and its var iation were investigated statistically in two different types and location of houses. In the single-storey slab-on-grade house (A), the variation of i ndoor radon closely followed the difference in indoor-outdoor temperature. The measured pressure difference across the wall and wind speed were signif icant variables (p <0.00), but these factors explained the variation of the radon concentration only slightly. In the two-storey hillside basement hou se (B), the most significant variable difference in indoor-attic space expl ained 28% of the variation of the indoor radon. In both houses, the coeffic ient of determination increased slightly when the average wind speed increa sed, but in house B the coefficient decreased with high wind speed. In hous e A, the highest concentration of indoor radon was observed as the wind-ind uced internal transport of radon. In house B, the highest concentration of indoor radon occurred and the highest coefficient of determination (100R(2) % = 89%) was observed when the wind was blowing towards the slope-side of t he esker, causing increased soil gas pressure and air flow in soil. Accordi ng to this study, the effect of the wind speed on the concentration of indo or radon and on the coefficient of determination was difficult to foresee b ecause the effect of the wind on soil depended strongly on the wind directi on and location of the houses. (C) 2000 Elsevier Science Ltd. All rights re served.