Designing Efficient Sub Slab Collection and Vapor Barrier Systems. Presented By: Tom Hatton Clean Vapor, LLC cleanvapor.com

Transcription

1 Designing Efficient Sub Slab Collection and Vapor Barrier Systems Presented By: Tom Hatton Clean Vapor, LLC cleanvapor.com 1

2 Effective and Efficient Vent Systems Start in the Planning Phase What is the history of contaminants in the soil? Phase I and Phase II Site Assessment Test On Site Buildings when Possible

3 Is There a Potential For Vapor Intrusion? Organic Vapors can travel 100 Feet Laterally and Vertically

4 Requirements for an Efficient Sub Slab Vent System Permeable sub slab material All under slab ground contact areas connected to a Soil Gas Conveyance Plenum Properly sized and streamlined under slab and riser piping A gas tight Vapor Barrier 4

5 Pressure Field Extension Sand Short pressure field extension Crushed Stone Increased pressure field extension Test fan Test holes 5

6 Permeable Sub Slab Support Material Proof Rolled Ground 8 ASSHTO #57 stone 4 free air flow Slab Cracking Slab Support 6

7 There Should be No Isolated Sub Slab Areas The collection system must be inclusive to the entire sub slab area within the occupancy envelope No isolated gravel beds Look for: Thickened slabs Grade changes 7

8 Sub Slab Piping Plumbing T fittings Standard vs. Chamfered Extensions Perforated Pipe Frequency of Drain Holes 8

9 Effective Soil Gas Collection Plenum Under slab piping should connect to a centrally located plenum box Larger diameter pipe with minimal fittings vents the plenum box to above the roof 9

10 GeoVent Highly efficient under slab plenum material Airflow properties similar to 4 PVC Most efficient when applied over crushed stone 10

11 GeoVent can be Used with under slab collection piping Installed for a fraction of the labor cost Lead to big savings 11

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13 Plenum Box Construction 13

14 Riser Pipes are Grouped for future pairing and efficient construction 14

15 Sizing Collection Pipes A function of service area and friction loss Pipe Diameter Service Area in Square Feet 3 1, , ,000 15

16 What Pipe Diameter Should be Specified? 16

17 Pressure Drop Pipe Diameter Per 100 of PVC Pipe at 100 CFM Pipe Diameter Straight Pipe Resistance Per 100 of PVC Pipe at 100 CFM 6 90 elbow elbow elbow NOTE: units in inches of water column 17

18 Soil Gas Probes Embedded prior to vapor barrier installation Drilling Holes in slab will: Void Liquid Boot Warrantee Risk Damaging sub slab utilities 18

19 Disadvantage to Conventional Barriers Mostly unsealed Only partially effective at preventing soil gas entry 19

20 Why Choose Liquid Boot? Near gas tight seal over: Crushed stone Collection plenum Unlike conventional barrier, it doesn t leak at Wall joints Column pads Utility penetrations 20

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22 Comparing Two Schools North Jersey School Standard Vapor Barrier and Vent System vs. Georgia School Liquid Boot Clean Vapor Vent System 38,000 ft 2 3 Story 24,000 ft 2 3 Story 22

23 4 crushed stone Original Design Schedule 80 sub slab piping Standard 3 plumbing Ts Many isolated areas Standard Polyethylene Vapor Barrier 39 vertical 3 risers North Jersey School watt roof mounted blowers Method of measuring pressure field extension Micromanometer, Drilling holes through slab and vapor barrier 23

24 4 crushed stone North Jersey School Schedule 80 sub slab piping Standard 3 plumbing Ts Amended Design Schedule 40 sub slab piping 4 chamfered Ts Many isolated areas No isolated areas Standard Polyethylene Vapor Barrier 39 vertical 3 risers 14 vertical 4 risers 14 - RP watt roof mounted blowers watt roof mounted blowers Method of measuring pressure field extension Micromanometer, Drilling holes through slab and vapor barrier 24

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26 4 Road Bed Georgia School 3-24 diameter pipes w/ 3/8 holes 1 ¼ inches O.C. Schedule 40 sub slab piping Some isolated areas Liquid Boot system 3 vertical 6 risers Original Design watt roof mounted blowers Method of measuring pressure field extension: Micromanometer, Drilling holes through slab and barrier 26

27 Georgia School Amended Design 4 Road Bed 6 AASHTO #57 stone 3-24 diameter pipes w/ 3/8 holes 1 ¼ inches O.C. 3 collection plenums w/ collection pipe Schedule 40 sub slab piping Some isolated areas No isolated areas Liquid Boot system 1 - vertical 6 riser 3 vertical 6 risers watt roof mounted blower watt roof mounted blowers Method of measuring pressure field extension: Micromanometer, Drilling holes through slab and barrier Embedded Probes 27

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29 24,000 ft 2 Depressurized with a Single 125 watt Blower

30 With Liquid Boot and an Efficient Sub Slab Collection System Design Vacuum distribution can be consistent and effective Suction Device Suction System In Riser Static Vac WC Air Flow CFM Watts Exhaust Diameter Test Probe Sub Slab Vacuum WC S T HP 220 S T S T T T

31 Final Performance Analysis North NJ Georgia Approx. Square Feet 38,000 24,000 Riser per Sq Ft One 4 per 2,700 One 6 per 24,000 Average Vacuum Sub Slab Blowers Estimated Annual Blower Cost * Est. Leakage per 10,000 Sq Ft Fourteen 118 watt blowers One 125 watt blower $457 $ CFM 49.5 CFM *cost per 10,000 ft 2 at $0.14 per KWH 31

32 Energy cost analysis Per 10,000 ft 2 of floor area North NJ Georgia Heating: **Factor H/E Cooling: * Factor C/E Overall Factor (E+H+C)/E = * Electric Cost at $0.14 per KWH ** Natural Gas Cost at $12.50 per 1,000 cubic feet 32

33 Energy Cost Analysis (cont.) North NJ Georgia Savings Electric* $457 $63 $394 Heating: ** $ 672 $77 $595 Cooling: * $96 $11 $85 Total Savings $1,074 * Electric Cost at $0.14 per KWH ** Natural Gas Cost at $12.50 per 1,000 cubic feet 33

34 Saving with Liquid Boot Per 10,000 ft 2 of floor area 4 Risers, average cost $4k per riser = $16,000 $394 per year in electricity $595 per year in heating $85 per year in cooling 57,697,920 cubic feet of heat loss* * Assuming a six month heating season 34

35 U.S. Dollars Savings with Liquid Boot and Efficient Sub Slab Venting System 140, , ,000 80,000 60,000 40,000 20,000 Liquid Boot Traditional VB Years 35

36 Conclusions Planned Sub Slab Ventilation Systems Highly Efficient Energy Savings Fiscally Sound Building Practice Improve Indoor Air Quality Contribute to Saving Lives 36

37 Acknowledgments Bill Brodhead, WPB Enterprises, Inc. Leo Moorman PhD, Radon Home Mitigation and Measurement Inc. Clean Vapor, LLC Team 37

38 Thanks for listening Presented By: Tom Hatton Clean Vapor, LLC cleanvapor.com 38