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Lesson 10 How can you reduce radon in a home? Slide 10-1 Brief overview of radon mitigation Mitigation: reducing radon in air or water Requires trained,

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Presentation on theme: "Lesson 10 How can you reduce radon in a home? Slide 10-1 Brief overview of radon mitigation Mitigation: reducing radon in air or water Requires trained,"— Presentation transcript:


2 Lesson 10 How can you reduce radon in a home?

3 Slide 10-1 Brief overview of radon mitigation Mitigation: reducing radon in air or water Requires trained, registered radon mitigation specialist –See listing at RS /radon/ Pubs/rpplist.pdf RS /radon/ Pubs/rpplist.pdf Typical radon mitigation system

4 Slide 10-2 Mitigation design EPA usually recommends methods that prevent radon from entering the home –Rather than reduce amount already present Design starts with visual inspection –Identify radon entry paths –Identify relevant construction features May require diagnostic tests

5 Slide 10-3 Methods for reducing radon in air Some methods depend on home construction, especially foundation design and materials Some methods apply to all foundation types Sealing foundation openings Home/room pressurization Heat recovery ventilation (HRV), or air-to-air heat exchange Natural ventilation

6 Slide 10-4 Sealing foundation openings Method Seal cracks and other openings to reduce radon entry Advantages Reduces loss of heated or cooled air Makes other methods more effective and cost-effective Disadvantages Difficult to identify and permanently seal all places where radon enters –Some areas are not accessible –Normal settling opens new cracks and reopens old ones Sealing alone does not reduce radon enough

7 Slide 10-5 Home/room pressurization Method Fan blows air from upstairs or outdoors into lowest living levels Increases pressure to reduce radon entry Disadvantages Requires doors and windows on lowest level to be kept closed except for normal entry and exit Introduces more outdoor air, so may increase moisture and energy costs Effectiveness limited by –Home construction –Climate –Appliances –Resident lifestyle Use only with other methods if they do not reduce radon enough

8 Slide 10-6 Heat-recovery ventilation (air-to-air heat exchange) Method Increases ventilation by bringing in outdoor air and removing indoor air Outgoing indoor air heats or cools incoming air Most effective when ventilating a limited space, such as a basement Can be used year-round Advantage Can improve overall air quality where there are other indoor pollutants Disadvantage Can significantly increase heating and cooling costs

9 Slide 10-7 Natural ventilation Method Opening windows, doors, and vents on lower levels increases ventilation Outdoor air mixes with indoor air, diluting radon Indoor and outdoor air pressure is equalized Disadvantages When openings are closed, radon returns to higher level in 12 hours Greatly increases energy costs because heated and cooled air is lost May make home uncomfortably hot or cold May make home less safe Use only as a temporary method

10 Slide 10-8 Methods for specific foundation types Concrete poured at ground level Shallow unfinished space below first floor Room partly or completely below ground

11 Slide 10-9 Basement and slab-on-grade options Suction prevents radon from entering home Draws radon from below home Vents radon to pipe(s) Releases radon to air above home Types of suction Subslab –Active –Passive Drain tile Sump hole Block wall

12 Slide 10-10 Active subslab suction (or subslab depressurization) Reliable Effective in reducing high radon levels Suction pipes inserted through slab into soil or crushed rock below Vent fan draws up radon gas and releases it outside, above the roof eave Works best when air moves easily under slab

13 Slide 10-11 Subslab suction Passive Similar to active system but Instead of fan, natural air pressure differences and air currents draw up radon gas Less effective in reducing high radon levels Usually used with radon- resistant features in newly built homes

14 Slide 10-12 Drain tile suction Drain tiles or perforated pipe direct water away from foundation Works with a partial or complete loop of drain tiles Suction pulls radon from soil and vents away from home

15 Slide 10-13 Sump hole suction Used in basement with sump pump designed to remove water Sump is capped and continues to operate Sump becomes location for radon suction pipe Works best when air moves easily to sump from under slab

16 Slide 10-14 Block wall suction Used in basement with hollow block foundation walls Requires that major openings be sealed Removes radon and depressurizes block wall Often used in combination with subslab suction

17 Slide 10-15 Crawlspace options Submembrane suction Active depressurization Crawlspace ventilation

18 Slide 10-16 Submembrane suction Method Cover earth floor with high-density plastic sheet Vent pipe and fan draw radon from under sheet and vent to outdoors Advantage Most effective method

19 Slide 10-17 Active depressurization Method Fan draws air from crawlspace Disadvantages Less effective than submembrane suction Requires special attention to backdrafts of combustion appliances Requires sealing crawlspace from rest of home May increase energy costs because heated or cooled air is lost

20 Slide 10-18 Crawlspace ventilation Methods Active: fan blows air through crawlspace Passive: vents circulate air naturally in crawlspace Disadvantages Water pipes, sewer lines, and appliances in crawlspace may need to be insulated against cold May increase energy costs May lower radon by 1. Reducing suction on soil 2. Diluting radon beneath a home

21 Slide 10-19 Various foundations may require various methods

22 Slide 10-20 Questions?

23 Slide 10-21 Removing radon in water from private wells Point-of-entry system Removes radon before water is distributed Treats all water in home Types –Granular activated carbon –Aeration Point-of-use system Removes radon from water at tap Treats only small percentage of household water Less effective than point-of-entry

24 Slide 10-22 Granular activated carbon (GAC) system Used to treat radon in water levels from 5,000 pCi/L to below 10,000 pCi/L Less expensive Filters water through carbon bed, which traps radon and radon decay products –Tank may emit some radiation and may require shielding –Filter must be changed each year

25 Slide 10-23 Aeration system Used to treat radon levels 10,000 pCi/L and above More expensive Mixes water with air and vents radon outdoors System does not become radioactive Requires yearly cleaning

26 Slide 10-24 Summary Mitigation should be done by qualified contractor Mitigation involves –Visual inspection –Consideration of home construction –Possibly diagnostic tests General mitigation methods –Sealing foundation openings –Home/room pressurization –Heat recovery ventilation –Natural ventilation

27 Slide 10-25 Summary Methods for slab- on-grade and basement foundations –Subslab suction –Drain tile suction –Sump hole suction –Block wall suction Methods for crawlspace foundation –Submembrane suction –Active depressurization –Crawlspace ventilation

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