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NRC and Radon Control Technologies

Prepared by: Dr. Liang Grace Zhou, Gang Nong, Ethan Li, and Jeff Whyte NRC Construction For: Spring Training Camp for Advanced Building Science and Practical Application 2018 May 3, 2018

HC-RPB cross-Canada survey of 14,000 homes: ~7% of Canadians living in homes with radon level >200 Bq/m3

Background

Lung cancer attributable to radon exposure: 1,100/yr in UK, 3,200/yr in Canada, 21,000/yr in the US

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NRC’s Radon Research •  Why:

•  Serve as a mission-driven channel for federal investment in R&D •  Provide the required technical inputs for health regulators, building officials,

standards committees, builders and radon practitioners •  Support the emerging “radon industry” •  Improve public awareness and offer verified solutions to radon issue

•  Funding sources: Federal Funding--Taking Action on Air Pollution Interdepartmental agreement with Health Canada Radiation Protection Bureau Fee for Service contracts with industrial clients

•  How: NRC’s multidisciplinary expertise, unique facilities, and links to industry: Building engineer, building scientist, mechanical engineer, radiologist, concrete and

structure engineer, electrical engineer, chemists CCHT, IARL, RIBETS, Radon Diffusion Test Chamber, fan leakage test rig, etc. Canadian Construction Material Centre and National Building Code Committees

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Radon requirements in National Building Code 2010

2010 NBC Part 9 – Application /Exemptions •  Applies to all housing and small buildings:

next slide

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Radon in the National Building Code 2010 Part 9

2010 NBC Part 9 Strengthened Basic Protection Applies to all housing and small buildings (NO government issued radon risk map) Reduced health burden for 2.5% of the housing stock each year (annual new housing (200T) divided by existing housing stock (8M))

•  Air barrier requirements (9.25.) •  For below-ground walls •  Polyethylene soil gas barrier required under slab (CAN/

CGSB-51.34-M86) •  Slab perimeter sealed to air barrier of the wall •  All penetrations (mostly pipes) sealed

•  Sump pit cover required to be airtight (9.14.) •  Consistent requirements for ground cover (9.18.)

New Performance Solution in Part 9

2010 NBC Part 9 – Rough-in

Capped and labeled pipe Top end ready for active system (Active sub-slab depressurization)

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Performance Solution – Large Buildings & optional for small non-residential buildings

2010 NBC Part 5 – Environmental Separation •  Control of Air Leakage (performance targets)

•  Minimize the ingress of airborne radon from the ground with an aim to controlling the indoor radon concentration to an acceptable level

2010 NBC Part 6 – HVAC •  Good HVAC Engineering Practice

•  EPA/625/R-92/016, “Radon Prevention in the Design and Construction of Schools and Other Large Buildings” Ventilation and ASD

Appendix Guidance •  Health Canada Guide for Radon Measurements in Public Buildings

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Radon Control Research Activities at NRC

•  Active sub-slab depressurization (ASD) and Passive Radon stack in labs Leakage through radon control fans

Energy penalty and impact on soil temperature

Insulation of stacks in unheated attic space

Backdrafting from combustion appliances

•  Prevent soil gas entry Sub-slab air permeable layer and air barrier systems

•  A combination of strategies

•  Indoor radon dilution Air tightness, air change rate, HRV, and radon concentration

Radon cross-contamination through HRV/ERV core unit

•  Full height passive radon stack

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ASD: Radon Fan Enclosure Leakage Test Rig

Why: Radon control fans are located in the basements of Canadian homes

How: NRC’s air permeability test apparatus and tracer gas leakage test rig

Who: 4 North American radon fan manufacturers

What: Test 5 models/8 fans for WG3

Outcomes: Radon fan criteria- CAN/CGSB-149.12-2017 Radon Mitigation

Options for Existing Low-Rise Residential Buildings

Canada US

(Illustratration courtesy of Health Canada)

ASD: Impact on Heating Energy Use and Soil Temperature Performance of Passive Radon stack

ASD with Ground Exhaust (2012)

ASD with Roof Line Exhaust (2012)

Expected Test House Daily Energy Consumption (MJ) 309.9 360.4

Increased Daily Consumption (MJ) 20.2 15.3

Increase, % 6.5% 4.2%

Canadian Centre for Housing Technology

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ASD: Stack Insulation, Backdrafting from Combustion Appliances, Gable-ended Discharge

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•  Insignificant risk of backdrafting from combustion appliances due to building depressurization

•  Gable-ended discharge is a viable routing for ASD •  R7 in unheated attic and R14 above roofline Canadian General Standards Board 149.11 and 149.12 “Radon-Reduction Guide for Canadians”, Health Canada-Radiation Protection Bureau “Illustrated User’s Guide to Part 9 of the National Building Code 2010”

Indoor Air Research Laboratory

Prevent Soil Gas Entry: Radon Infiltration Building Envelope Test System (RIBETS)

Radon infiltration through floor assembly with •  Membrane •  Special property concrete •  Sub-slab ventilation panel •  Sub-slab spray foam •  HVAC components (HRV/ERV) and demand control

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Prevent Soil Gas Entry: Radon Diffusion Test Chamber

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Material evaluation ISO/TS 11665-13: 2017

•  Special property concrete •  Membrane •  Sub-slab spray foam •  Foam board and tape •  Sealant

CCMC Technical Guide for “Medium Density (MD) Spray Polyurethane Foam Insulation (SPUF) for Soil Gas (Radon) Control beneath Concrete Slabs-on-Ground” 2017

A Combination of Strategies: CCHT Semi-Detached Net-Zero Energy-ready Smart Home

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A verified sub-slab ventilation panel, a verified radon prevention membrane, Form-a-Drain, 4 radon stacks Extensive sensors for monitoring sub-slab pressure, soil temperature, stack flow/RH/T/V.

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Indoor Radon Dilution Air Tightness, Air Change Rate, and HRV

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y  =  3.9188e-­‐0.244xR²  =  0.9994

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5

Average  SF6  Curve  Fitting  HRV#1OnHRV#2Off

MEAN Expon.  (MEAN)

A two-storey single house of 1450 ft2 with 2 HRV units

y  =  2.2565e-­‐0.045xR²  =  0.9944

0

0.5

1

1.5

2

2.5

0 5 10 15 20

Average  SF6  Curve  Fitting  HRV#1OffHRV#2Off

MEAN Expon.  (MEAN)

y  =  1.9022e-­‐0.404xR²  =  0.9985

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Average  SF6  Curve  Fitting  HRV#1OnHRV#2Off

MEAN Expon.  (MEAN)

Tracer gas decay test

HRV#1 Off and HRV#2 Off, ACH =0.045

HRV#1 On and HRV#2 Off, ACH =0.244

HRV#1 On and HRV#2 On, ACH =0.404

Blower door test

0.79 ACH @-50 Pa

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A two-storey single house of 1450 ft2 with 2 HRV units

HRV#1 On and HRV#2 Off, range between 17 and 74 Bq/m3, average 43.7 Bq/m3

HRV#1 Off and HRV#2 Off, increased from 16 Bq/m3 to 222 Bq/m3 within 18 hours

HRV#1 On and HRV#2 On, decreased from 120 Bq/m3 to 33 Bq/m3 within 4 hours

0

50

100

150

200

250

7/11/17 7:127/11/17 8:247/11/17 9:367/11/17 10:487/11/17 12:007/11/17 13:127/11/17 14:247/11/17 15:367/11/17 16:487/11/17 18:007/11/17 19:127/11/17 20:247/11/17 21:367/11/17 22:487/12/17 0:007/12/17 1:127/12/17 2:247/12/17 3:367/12/17 4:487/12/17 6:007/12/17 7:127/12/17 8:247/12/17 9:367/12/17 10:487/12/17 12:007/12/17 13:127/12/17 14:24

Rn

(Bq/

m3)

Date and Time

Rn Concentration

HRV#1 ON HRV#2 OFF AG BSMT

HRV#1 OFF HRV#2 OFF AG BSMT

HRV#1 ON HRV#2 ON AG BSMT

HRV#1 ON HRV#2 OFF corentium BSMT

HRV#1 OFF HRV#2 OFF corentium BSMT

HRV#1 ON HRV#2 ON corentium 1st floor

Indoor Radon Dilution Air Tightness, Air Change Rate, HRV, and Radon

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Illustratration courtesy of Natural Resources Canada (left) and Health Canada cross Canada radon survey (right)

Indoor Radon Dilution: HRV for Radon Control

House with high airtightness and moderately high levels of radon

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Full height Passive Radon Stack: a Field Study in the National Capital Region

December 2014, the British Columbia Building Code provisions for Area 1 (radon-prone areas). 3 National Building Code change requests to standing committee on housing and small buildings. Current study: 5 homes in Ottawa-Gatineau, >30 day stack open, >30 day stack closed, Fall&Winter Measurements: radon concentration(indoor, soil, and stack); sub-slab pressure; P/T/RH flow rate and air speed in the stack; tracer gas test for air exchange rate; blower door test.

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Full Height Passive Radon Stack Field Study: Radon Concentration from the Basement

Closed stack: 150 Bq/m3 165 Bq/m3 117 Bq/m3

Open stack: 110 Bq/m3 (36%) 12 Bq/m3 (92%) 22 Bq/m3 (81%)

Closed stack: 140 Bq/m3

Open stack: 68 Bq/m3 (51%)

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Full Height Passive Radon Stack Field Study: Other Measured Parameters

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Future Work: 2018 and Beyond

•  Database of building material for radon control

•  Phase II of Field study of full size passive radon stack in BC (15 homes): radon

control and design/installation guide

•  A field study of HRV for indoor radon control

•  Radon and indoor air quality in Energy Star and/or Net Zero Buildings

•  Discharged radon dispersion (measurement from mitigated homes and CFD)

•  Radon measurement and intervention in daycares/schools and workplaces with

elevated radon levels

•  Soil gas sampling + indoor air/radon monitoring + building study

•  Applying verified radon control products in new constructions

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Thank you

Liang Grace Zhou Senior Research Officer 613-990-1220 Liang.zhou@nrc-cnrc.gc.ca

www.nrc-cnrc.gc.ca

https://www.ottawacommunitynews.com/news-story/7687739-lung-association-launches-radon-awareness-month/ November is Radon Action Month in Canada!