IMPACT OF SUBSLAB VENTILATION TECHNIQUE ON RESIDENTIAL VENTILATION RATE AND ENERGY COSTS

Radon is the largest source of risk to human health caused by an indoo r pollutant in the industrial countries. Subslab ventilation (SSV) is one of the most effective and common methods of reducing indoor radon concentrations in houses with a basement. In this paper, the impact of SSV on the air exchange rate is quantified, through numerical modelin g of a prototype house with basement for a range of permeabilities of soil and subslab aggregate and various sizes of the cracks in the base ment floor. We show that a SSV system can increase the air exchange ra te by as much as a factor of 4.5. Then the energy and capital costs of a subslab depressurization (SSD) system are compared with those of di rect ventilation of the basement which is required to lower the indoor radon concentration to an acceptable level for a Chicago climate. We show that (1) an exhaust ventilation cannot significantly reduce the i ndoor radon concentration and may even increase it, and (2) a balanced ventilation with heat recovery is only effective for low premitigatio n radon concentrations. However, both SSV and balanced ventilation sys tems are probably too expensive to be recommended in houses with low p remitigation radon concentrations. A SSD system is the most cost-effec tive technique for reduction of high radon concentrations.