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INSTALLATION AND OPERATING COST TABLE Technique Typical Radon Reduction Comments Subslab Suction (Subslab Depressurization) 50 to 99 percent Works best if air can move easily in material under slab. Passive Subslab Suction 30 to 70 percent May be more effective in cold climates; not as effective as active subslab suction. Draintile Suction 50 to 99 percent Can work with either partial or complete drain tile loops. Block-Wall Suction 50 to 99 percent Only in homes with hollow block-walls; requires sealing of major openings. Sump-Hole Suction 50 to 99 percent Works best if air moves easily to sump from under the slab. Submembrane Depresserization in a Crawlspace 50 to 99 percent Less heat loss than natural ventilation in cold winter climates. Natural Ventilation in a Crawlspace 0 to 50 percent Costs variable. Sealing of Radon Entry Routes See Comments Normally only used with other techniques; proper materials and installation required. House (Basement) Pressurization 50 to 99 percent Works best with tight basement isolated from outdoors and upper floors. Natural Ventilation Variable/Temporary Significant heated or cooled air loss; operating costs depend on utility rates and amount of ventilation. Heat Recovery Ventilation (HRV) Variable/ See comments Limited use; effectiveness limited by radon concentration or the ammount of ventilation air available for dilution by the HRV. Best Applied in limited-space areas like basements. Private Well Water Systems: Aeration 95 to 99 percent Generally more efficient than GAC; requires annual cleaning to maintain effectiveness and to prevent contamination; requires venting radon to outdoors. Private Well Water Systems: Granular Activated Carbon, or GAC 85 to 95 percent Less efficient for higher levels than aeration; use for moderate levels, around 50,000 pCi/L or less in water: radioactive radon by-products can build on carbon; may need radiation shield around tank and care in disposal. Note: Mitigation costs vary due to technique, materials, and the extent of the problem. Typically the cost of radon mitigations are comparable to other common home repairs. 16 A Consumer's Guide To Radon Reduction