Lesson 10 How can you reduce radon in

Lesson 10 How can you reduce radon in a home?

Brief overview of radon mitigation • Mitigation: reducing radon in air or water • Requires trained, registered radon mitigation specialist – See listing at www. dph. state. ct. us/B RS /radon/ Pubs/rpplist. pdf Typical radon mitigation system 1

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 2

Methods for reducing radon in air 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 Some methods depend on home construction, especially foundation design and materials 3

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 4

Home/room pressurization Method • Fan blows air from upstairs or outdoors into lowest living levels • Increases pressure to reduce radon entry Use only with other methods if they do not reduce radon enough 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 5

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 6

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 7

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

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

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 10

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 radonresistant features in newly built homes 11

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 12

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 13

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 14

Crawlspace options • Submembrane suction • Active depressurization • Crawlspace ventilation 15

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 16

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 17

Crawlspace ventilation May lower radon by 1. Reducing suction on soil 2. Diluting radon beneath a home 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 18

Various foundations may require various methods 19

Questions? 20

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 21

Granular activated carbon (GAC) system • Used to treat radon in water levels from 5, 000 p. Ci/L to below 10, 000 p. Ci/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 22

Aeration system • Used to treat radon levels 10, 000 p. Ci/L and above • More expensive • Mixes water with air and vents radon outdoors • System does not become radioactive • Requires yearly cleaning 23

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 24

Summary • Methods for slabon-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 25