In-duct air cleaning devices: ozone emission rates and test ......Contract No. 09-342 In-duct air cleaning devices: Ozone emission rates and test methodology Principal Investigators:

Contract No. 09-342

In-duct air cleaning devices: Ozone emission rates and test methodology

Principal Investigators: Glenn Morrison1, Richard Shaughnessy2, Jeffrey Siegel3

1Missouri University of Science and Technology, Rolla, MO 2University of Tulsa, Tulsa, OK

3University of Texas, Austin, TX and University of Toronto, ON

Contractor Organization: The Curators of the University of Missouri on behalf of Missouri University of Science

and Technology

Prepared for the California Resources Board and the California Environmental Protection Agency

March 31, 2014

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Disclaimer

The statements and conclusions in the Report are those of the contractor and not necessarily those of the California Air Resources Board. The mention of commercial

products, their source, or their use in connection with material reported herein is not to be construed as actual or implied endorsement of such products.

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Acknowledgement (1)

This Report was submitted in fulfillment of 09-342 In-duct Air Cleaning Devices: Ozone Emission Rates and Test Methodology by the Curators of the University of Missouri on behalf of Missouri University of Science and Technology under the sponsorship of the California Air Resources Board. Work was completed as of March 31, 2014.

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Acknowledgement (2)

The authors thank Jeffrey Williams, Peggy Jenkins and Tom Phillips of the Research Division of the Air Resources Board for their effective technical management of this project. We also acknowledge the experimental, modeling and data analysis contributions of David Reisdorph, Nishanthini Vijayakumar Shakila, Mikhil Shetty, Atila Novoselac, Kristia Parker, Joshua Rhodes, Megan Gunther, Christina Phensy, Mark Jackson, and Shahana Khurshid Great thanks go to the volunteers who allowed our research teams to test air cleaners in their homes, Jonathan Reyes of Sawyer Heating for his help in locating homes and the following individuals and companies for donating air cleaners for testing: Ron Saunders and Chris Willette of FreshAire UV; Jim Rosenfeld of TexAire Filters.

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Table of contents Table of contents....................................................................................................................... v List of Figures.......................................................................................................................... vii List of Tables ........................................................................................................................... xii Abstract .....................................................................................................................................xiv Executive Summary ...............................................................................................................xv Introduction .......................................................................................................................................xv Methods................................................................................................................................................xv Results ................................................................................................................................................ xvi Conclusions........................................................................................................................................xix

1 Introduction.......................................................................................................................11.1 Health Effects .........................................................................................................................11.2 Indoor ozone concentrations and sources..................................................................11.3 Development of list of devices to test ...........................................................................4 1.4 Laboratory test method development and device testing.....................................5 1.5 Field testing............................................................................................................................51.6 Building simulations ...........................................................................................................5

2 Materials and methods ..................................................................................................7 2.1 Candidate device survey....................................................................................................72.1.1 Candidatedevicesurvey inCaliforniaresidences ............................................................72.1.2 Contactwithagencies...................................................................................................................7 2.1.3 Recommendationsfordevicetesting.....................................................................................8

2.2 Laboratory test method development and device testing.....................................8 2.2.1 StandardTestMethoddevelopment......................................................................................82.2.2 Devicetesting................................................................................................................................14

2.3 Field testing......................................................................................................................... 15 2.3.1 Tulsatesthomeselection.........................................................................................................16 2.3.2 Tulsatesthousemethod ..........................................................................................................18 2.3.3 Testperiodsandlessonslearned .........................................................................................18 2.3.4 Recruiting,selectionanddescriptionofCaliforniaHomes........................................20 2.3.5 Californiaresidentialtestmethod........................................................................................23

2.4 Building simulations ........................................................................................................ 32 2.4.1 Singlezonemodel.......................................................................................................................322.4.2 Parameters.....................................................................................................................................34 2.4.3 Reviewofparametersusedinsinglezonemodel..........................................................41 2.4.4 Multizonemodel: CONTAMsimulations............................................................................41

3 Results............................................................................................................................... 473.1 Candidate device survey................................................................................................. 473.1.1 Devicesandtechnologies identified....................................................................................47 3.1.2 CandidatedevicesurveyinCaliforniaresidences.........................................................49 3.1.3 Contactwithagencies................................................................................................................51 3.1.4 Recommendationsfordevicetesting..................................................................................52 3.1.5 Devicesactuallyacquired fortesting..................................................................................52

3.2 Laboratory test method development and device testing.................................. 53 3.2.1 Testmethoddevelopment.......................................................................................................53

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3.2.2 StandardTestMethod(STM) for measuringozone emission ratesfromelectricallyconnectedin‐ductaircleaners.......................................................................................553.2.3 Standardtestmethodqualification and determination of quantificationlimit 67 3.2.4 Ozoneemissionratesfrom electricallyconnectedin‐duct devices........................70

3.3 Field testing......................................................................................................................... 82 3.4 Building ozone concentration simulations .............................................................. 93 3.4.1 Singlezone.....................................................................................................................................933.4.2 Multiplezone.................................................................................................................................98

4 Discussion......................................................................................................................1134.1 Application of Standard Test Method ......................................................................113 4.2 Comparison of field results with prior literature................................................114 4.3 House conditions and reactivity ................................................................................115 4.4 Comparison of laboratory and field emission rate results ..............................116 4.5 Comparison of ozone increase vs predicted..........................................................116 4.6 Use of theoretical models to predict indoor air concentrations ....................117 4.7 Applying building simulation models to measured ozone emission rates 118 4.8 Other impacts of the use of ozone‐emitting in‐duct air cleaners...................118

5 Summary and Conclusions.......................................................................................1215.1 Laboratory test method and device testing ...........................................................121 5.1.1 Testmethod................................................................................................................................1215.1.2 Devicetesting............................................................................................................................. 121

5.2 Field tests ...........................................................................................................................121 5.3 Building ozone concentration simulations ............................................................122 5.4 Conclusions........................................................................................................................123

6 References .....................................................................................................................125 7 List of inventions and publications ......................................................................131 8 Glossary of Terms, Abbreviations, and Symbols..............................................132 9 Appendices....................................................................................................................1349.1 Device descriptions ........................................................................................................134 9.2 Detailed results of laboratory testing of electrically connected in‐duct devices using the Standard Test Method ..............................................................................149 9.3 Survey of homes for Tulsa Testing in November 2011......................................168 9.4 California induct device testing checklist for homes .........................................170 9.5 California induct device testing checklist for commercial test.......................174 9.6 Description, images, plan drawings and data for California Test houses..178 9.6.1 California TestHouse1.......................................................................................................... 1789.6.2 California TestHouse2.......................................................................................................... 186 9.6.3 California TestHouse3.......................................................................................................... 193 9.6.4 California TestHouse4.......................................................................................................... 199 9.6.5 California TestHouse5.......................................................................................................... 208 9.6.6 California TestHouse6.......................................................................................................... 215 9.6.7 CaliforniaCommercialTest.................................................................................................. 223

9.7 Tulsa test house detailed results ...............................................................................229 9.8 Example steady state model calculations...............................................................240 9.9 Example CONTAM project file.....................................................................................241

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List of FiguresFigure2.1. Concentrationrise asa functionof flowforin‐ductaircleaners with

different emissionrates.................................................................................................................9Figure2.2. Ozonesamplinggrid usedtomeasureozoneupstream anddownstream

ofaircleaner....................................................................................................................................12Figure2.3. Schematicoftestduct. ................................................................................................... 13Figure2.4. Photographoftest apparatus ..................................................................................... 14Figure2.5.Tulsatesthousefloorplan&samplingsites(nottoscale). .......................... 17Figure2.6. Ozonepenetrationpredicted forresidentialHVACsystems. ....................... 40Figure2.7.FloorplanofbuildingAH‐14(a)andCONTAM3.0representation(b)of

buildingwithamainfloor andanattic.Diamonds()representleakageacross inner(doors)orouterwalls(windows), representssupply(BR1,BR2,K,BT)orreturn(LR)registers, representsozonesinksand isaplace‐holdersymbolforzoneinformation.................................................................................................... 43

Figure2.8. Ambientozoneconcentrationvstimeforsingle‐day, dynamicCONTAM3.0simulations. ..............................................................................................................................45

Figure3.1. Testing atdifferent intervallengthsforAC 5b....................................................69Figure3.2.Emissionratemeasurementsfor 10replicatetestsonAir Cleaner1 for

thepurposesofMQLassessment(SectionSTM10.5).Uncertainty not shownforgraphclarity. ............................................................................................................................70

Figure3.3.Emissionratesfor eight aircleanersfrompreliminary testing.Thebottomoftheboxindicatesthe25thpercentile,thehorizontal lineindicatesthe median and thetopoftheboxthe75thpercentile. Thewhiskers indicatethedatarange within 1.5timestheinterquartile rangeof the 25th and75thpercentile. Filledcirclesareoutliers..................................................................................... 71

Figure3.4. Flowrates correspondingto emissionratetestsin Figure 3.3.Thebottom oftheboxindicatesthe 25thpercentile,thehorizontallineindicatesthemedianandthetop oftheboxthe75thpercentile.Thewhiskers indicate the datarangewithin 1.5timestheinterquartile rangeofthe 25thand75thpercentile.Filledcirclesare outliers.........................................................................................................................72

Figure3.5.Emissionratesfor 12aircleaners. Aircleaner2b resultsfrompreliminary testing.Resultsfromaircleaner8 areshown intheinset becausetheemission ratesare muchhigherthanallotheraircleaners. Thebottomoftheboxindicatesthe 25thpercentile,thehorizontalline indicatesthe median andthetop oftheboxthe75thpercentile.Thewhiskers indicate the datarangewithin 1.5timestheinterquartile rangeofthe 25thand75thpercentile.Filledcirclesare outliers.........................................................................................................................73

Figure3.6. Flowrates correspondingto emissionratetestsin Figure 3.5.Thebottom oftheboxindicatesthe 25thpercentile,thehorizontallineindicatesthemedianandthetop oftheboxthe75thpercentile.Thewhiskers indicate the datarangewithin 1.5timestheinterquartile rangeofthe 25thand75thpercentile. .......... 74

Figure3.7.Ozoneemissionrateatlowesttestedflow.Figure 3.7a includesaircleaners1‐7onlyforclarity;Figure3.7bshowsthesameresults,butalso

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includesair cleaner 8 whichhad amuchhigheremission ratethan aircleaners 1‐7.Correspondingflowrate appearsabovebars(m3 h‐1). SeenotesintextaboutdeviationsfromstandardwhentestingAirCleaner2b...................................75

Figure3.8. Ozone emissionrate as afunction offlowratefor alltestedaircleaners.Resultsforaircleaner 8areshowninthe insetbecausetheemission rate ismuchhigherthanotheraircleaners..................................................................................... 77

Figure3.9. Ozone emissionrateas a functionoftemperaturefor Air Cleaner3. ....... 78 Figure3.10.Ozoneemissionrate as afunction ofrelative humidityfor AirCleaner3.

...............................................................................................................................................................79Figure3.11.Ozoneemissionrate asafunctionofflowrateand different

environmentalconditionsforAir Cleaner3......................................................................79Figure3.12.Ozoneemissionrate asafunctionofflowrateand different

environmentalconditionsforAir Cleaner5b...................................................................80Figure3.13.Emissionrate forrepeatedtestsonAir Cleaner5a. Test 2startedat the

highflowrate. .................................................................................................................................81Figure3.14.Emissionrate forrepeatedtestsonAir Cleaner5b.Tests2and4

startedatthehighflowrate. Onedatapoint excludedfromTest1becauseofavalvetimingerrorwiththeapparatus................................................................................. 81

Figure3.15. Steady‐stateincrementalincrease intheindoorozoneconcentration atallfieldsitesatreturn.................................................................................................................. 87

Figure3.16.Ozoneemissionrates forfieldsites.Whitebar is OER1,blackbarisOER2. ..................................................................................................................................................89

Figure3.17. Evidence oftheozone emission ratebeinginfluencedbytemperatureinCaliforniatesthouse4.Indoorconcentration increaseswhenHVACheateroperating...........................................................................................................................................90

Figure3.18.Ozonedecayrates(ODR)atfieldsites.NoODRwas obtainedattheclassroomsitewiththe TraneTCACSsystem...................................................................92

Figure3.19.Airexchangerates measuredat fieldsites.The AERwasnotmeasured usingCO2 decayinthe classroomsitewiththe TraneTCACSsystem.................... 92

Figure3.20.Ozoneconcentration asafunction ofsourceemissionrateand airexchangeratefor theStandardHouse.................................................................................94

Figure3.21.Ozoneconcentration asafunction ofair exchange rateandsourceemission ratefor theStandardHouse.................................................................................. 94

Figure3.22.Ozoneconcentration asafunction ofair exchange rateandbuildingvolumefortheStandardHouse. ............................................................................................. 95

Figure3.23.Ozoneconcentration asafunction ofair exchange rateandcombinedremovalratefortheStandardHouse. .................................................................................. 96

Figure3.24.Ozoneconcentration asafunction ofair exchange rateandsource emission ratefor theStandard Housewithoutdoorozoneinfiltration. ............... 97

Figure3.25.Ozoneconcentration asafunction ofsourceemissionrateforthe AtRiskHouse........................................................................................................................................98

Figure3.26. Steady‐stateozoneconcentrationsimulationformultizonemodel.Aircleanerat100%dutycycle,AHUoff,windfrom0°. ...................................................... 99

Figure3.27. Steady‐stateozoneconcentrationsimulationformultizonemodel.Aircleanerat100%dutycycle,AHUoff,windfrom90°..................................................... 99

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Figure3.28. Steady‐stateozoneconcentrationsimulationformultizonemodel.Aircleanerat100%dutycycle,AHUoff,windfrom135°. ................................................99

Figure3.29. Steady‐stateozoneconcentrationsimulationformultizonemodel.Aircleanerat100%dutycycle,AHUoff,windfrom180° ..................................................99

Figure3.30. Steady‐stateozoneconcentrationsimulationformultizonemodel.Aircleanerat100%dutycycle,AHUoff,windfrom270° ............................................... 100

Figure3.31.Steady‐stateconcentrationforeach roominthemultizonehouse.Airhandlerisonfulltime(100%),winddirection is0°,depositionvelocityislow(a)orhigh(b),ambientconcentrationisset to zero.................................................. 100

Figure3.32.Steady‐stateconcentrationforeach roominthemultizonehouse.Airhandlerisonfulltime(100%),winddirection is90°,deposition velocityislow(a)orhigh(b),ambientconcentrationisset to zero.................................................. 101

Figure3.33.Steady‐stateconcentrationforeach roominthemultizonehouse.Airhandlerisonfulltime(100%),winddirection is135°,deposition velocityislow(a)orhigh(b),ambientconcentration issettozero. ........................................ 101



Figure3.36.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneset tozero,ozonesourceonsame1‐houron/offcycle,lowdepositionvelocity. ............................... 102

Figure3.37.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneset tozero,ozonesourceon1‐houron/offcycle,highdeposition velocity........................................... 103

Figure3.38.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneset tozero,ozonesourceonatalltimes,low depositionvelocity.............................................................. 104

Figure3.39.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneset tozero,ozonesourceonatalltimes, highdepositionvelocity. ........................................................... 104

Figure3.40.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration, ozonesourceOFF,lowdepositionvelocity. ................................................................................. 105

Figure3.41.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration, ozonesourceOFF,highdeposition velocity................................................................................. 106

Figure3.42.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle,ambientozoneinfiltration,ozonesourceon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),(50%dutycycle),lowdeposition velocity........107

Figure3.43.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration,ozonesourceon1‐houron/offcycle,highdeposition velocity........................................... 108

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Figure3.44.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration, ozonesourceonatalltimes,low depositionvelocity.............................................................. 108

Figure3.45.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration, ozonesourceonatalltimes,lowdepositionvelocity.(2hourselectionfromFigure3.44tobettershowroom‐specificozonedynamics).................................................. 109

Figure3.46.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration, ozonesourceonatalltimes, highdepositionvelocity. ........................................................... 110

Figure3.47.Dynamicindoorozone concentrationfor:airhandlingsystemon1‐houron/offcycle(AHUon0‐1h,off1‐2 h,etc.),ambientozoneinfiltration, ozonesourceonatalltimes, highdepositionvelocity.(2hourselection fromFigure3.46toshowroom‐specificozone dynamics) ............................................................... 110

Figure3.48.Dynamicindoorozone concentrationfor:airhandling systemandsourceona20%dutycycle(5minon,20minoff),ambientozonesettozero,lowdepositionvelocity............................................................................................................ 111

Figure3.49.Dynamicindoorozone concentrationfor:airhandling systemandsourceona20%dutycycle(5minon,20minoff),ambientozonesettozero,lowdepositionvelocity.(2hourselection)..................................................................... 112

Figure3.50.Dynamicindoorozone concentrationfor:airhandling systemandsourceona20%dutycycle(5minon,20minoff),ambientozone infiltration,lowdepositionvelocity............................................................................................................ 112

Figure4.1. Comparison ofozone emissionratesmeasuredusingthe StandardTestMethod(lab)andestimatedfrom fielddata(Field). .................................................. 116

Figure4.2.Comparison of1)predictedozoneconcentrationbasedonlaboratorymeasuredemissionrateand2)average incrementalincreasemeasuredinfieldsites................................................................................................................................................... 117

Figure4.3 Ozoneand reactionproductconcentrations resulting from theuseofanozoneemittingdevice intheStandardHome................................................................ 120

Figure9.1.Bio‐FighterLightstickimagefrom productliterature. ................................. 135Figure9.2.RGFGuardianAirimage fromproductliterature. .......................................... 136Figure9.3.HoneywellF300ElectronicAirCleanerimagefromproductliterature.

............................................................................................................................................................ 138Figure9.4. LennoxPureAirimagefromproductliterature............................................... 140Figure9.5. activTekINDUCT2000 imagefromproductliterature................................ 141Figure9.6. Air‐ZoneAir‐Duct 2000images fromproduct literature. ........................... 142Figure9.7. APCOFresh‐aire image fromproductliterature. ............................................ 143Figure9.8. HVACUV560image fromproduct literature................................................... 145Figure9.9. TraneCleanEffectsimagefromproductliterature. ...................................... 146Figure9.10.TCACSimagefromproductliterature............................................................... 148Figure9.11. Plandrawingoftesthouse1includingsample locations andlocation of

supplyandreturnvents. ......................................................................................................... 179Figure9.12.ImageoffrontofTest House1andlocationofsupplysamplingin

masterbedroom.......................................................................................................................... 180Figure9.13.Imageoflocation oflivingroomsampling...................................................... 180

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Figure9.14.Imageofdevicetested(activTekINDUCT2000)asinstalledin airhandlingsystem.......................................................................................................................... 181

Figure9.15. PlandrawingofTestHouse2includingsample locations andlocation of............................................................................. 188

supplyandreturnvents(nottoscale).............................................................................. 187Figure9.16.ImageoffrontofTest House2.Figure9.17.Imageoflocationofsupplysampling................................................................ 188Figure9.18.Imageofdevicetested(Trane Clean EffectsTraneClean Effects)as

installedin airhandlingsystem...........................................................................................189Figure9.19PlandrawingofTest House3includingsamplelocations andlocationof

supplyandreturnvents(nottoscale).............................................................................. 194Figure9.20.ImageoffrontofTest House3.............................................................................. 195Figure9.21.Imageoflocationofsamplingatreturn. .......................................................... 195Figure9.22.Imageofmonitoringsiteinmasterbedroom. ............................................... 196Figure9.23. PlandrawingofTestHouse4includingsample locations andlocation of

supplyandreturnvents(nottoscale).............................................................................. 200Figure9.24.ImageoffrontofTest House4.............................................................................. 201Figure9.25.Imageoflocationofsamplingatreturn. .......................................................... 202Figure9.26. ImageofHVAC UV560andactivTekINDUCT2000 installedafterair

handler............................................................................................................................................ 203Figure9.27. PlandrawingofTestHouse5includingsample locations andlocation of

supplyandreturnvents(nottoscale).............................................................................. 209Figure9.28.ImageoffrontofTest House5.............................................................................. 210Figure9.29.ImageofHVACUV560installedinplenumafterfan................................. 211Figure9.30.Imageofmonitors inlivingroom........................................................................ 212 Figure9.31. PlandrawingofTestHouse6includingsample locations andlocation of

supplyandreturnvents(nottoscale).............................................................................. 216Figure9.32.ImageoffrontofTest House6.............................................................................. 217Figure9.33.ImageofHoneywellEP installed. ........................................................................ 218 Figure9.34.Imageofmonitors in masterbedroom. ............................................................ 219Figure9.35.PlandrawingofCommericalTestclassroomincludingsamplelocations

andlocation ofsupplyandreturn vents(nottoscale).............................................. 224Figure9.36.ImageofCommercialTestclassroom................................................................ 225Figure9.37.ImageofTCACSroof‐topunitaboveclassroom............................................ 225Figure9.38.Imageofoutdoormonitoringsitonclassroomroof. .................................. 226

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List of Tables

Table2.1.Aircleaning ...............................................36

technologies testedin apparatususing theStandardTestMethod ...............................................................................................................................................15

Table2.2.Airexchangerates forresidentialbuildings(h‐1).Table2.3.Residentialbuildingvolumes(m3).............................................................................37Table2.4. Majorparametervaluesusedinsinglezonemodel. ..........................................41Table2.5.Selectedparameters usedin CONTAMsimulationusing buildingAH‐14.

Seesection 9.8forinputfileswith detailsofotherinputparameters...................43Table2.6.Simulationparametersappliedtosteady‐state anddynamicsimulations.

BASEcasevaluesarebold. ........................................................................................................ 46Table3.1.Preferredmanufacturers:responsesfromCaliforniainstallers. ..................50Table3.2.Popularelectronicaircleaners.................................................................................... 51Table3.3.Initiallistof devicestobetestedusinglaboratoryozoneemissionstest

method...............................................................................................................................................52Table3.4.Devices tested.SeeAppendix9.1 for descriptionsanddetailsofeach

device.For laboratorytesting, deviceswerenumberedasshown inTable3.3.53Table3.5. MajorSectionsinStandardTestMethod.................................................................54Table3.6.Qualification resultsfortestapparatus,Summer2012....................................68Table3.7. MajorresultsfromTulsatesthouse..........................................................................83Table3.8. MajorresultsfromCaliforniatest houses1‐3.......................................................85Table3.9. MajorresultsfromCaliforniatest houses4‐6.......................................................86Table9.1.Devices testedin laboratoryand/or field ............................................................ 134 Table9.2.Detailedresultsfromlaboratorytestingofdevice1....................................... 149 Table9.3.Detailedresultsoflaboratorytesting Aircleaner 2a. ..................................... 150 Table9.4.Detailedresultsoflaboratorytesting Aircleaner 2b...................................... 151 Table9.5.Detailedresultsoflaboratorytesting Aircleaner 2c....................................... 152 Table9.6.Detailedresultsoflaboratorytesting Aircleaner 3,part1.......................... 153 Table9.7.Detailedresultsoflaboratorytesting Aircleaner 3,part2.......................... 154 Table9.8.Detailedresultsoflaboratorytesting Aircleaner 3,part3.......................... 155 Table9.9.Detailedresultsoflaboratorytesting Aircleaner 4......................................... 156Table9.10. Detailed resultsoflaboratorytestingAircleaner 5a,part1.....................157Table9.11. Detailed resultsoflaboratorytestingAircleaner 5a,part2.....................158Table9.12. Detailed resultsoflaboratorytestingAircleaner 5b,part1..................... 159Table9.13. Detailed resultsoflaboratorytestingAircleaner 5b,part2..................... 160Table9.14. Detailed resultsoflaboratorytestingAircleaner 5b,part3..................... 161Table9.15. Detailed resultsoflaboratorytestingAircleaner 5b,part4..................... 162Table9.16. Detailed resultsoflaboratorytestingAircleaner 5b,part5..................... 163Table9.17. Detailed resultsoflaboratorytestingAircleaner 6a.................................... 164Table9.18. Detailed resultsoflaboratorytestingAircleaner 6b. .................................. 165Table9.19. Detailed resultsoflaboratorytestingAircleaner 7...................................... 166Table9.20. Detailed resultsoflaboratorytestingAircleaner 8...................................... 167Table9.21. SummaryofTestHouse1resultsincludingair exchangerates,ozone

decayrates, incremental increaseinozoneconcentration andozoneemissionrates.................................................................................................................................................. 182

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Table9.22. ........................................ 184

TestHouse 1AER/ODR May2210:30,TestConditions. ............................ 183Table9.23. TestHouse 1OERMay 2213:26,TestConditions.Table9.24. Testhouse 1OERMay 2312:20,testconditions. .......................................... 185Table9.25. SummaryofTestHouse2resultsincludingair exchangerates,ozone


Table9.26. TestHouse 2AER/ODR May2515:25,TestConditions. ............................ 191Table9.27. TestHouse 2OERMay 2510:16,TestConditions......................................... 192Table9.28. SummaryofTestHouse3resultsincludingair exchangerates,ozone


Table9.29. TestHouse 3AER/ODR May3014:03,TestConditions. ............................ 197Table9.30. TestHouse 3OERMay 309:05,TestConditions. .......................................... 198Table9.31. SummaryofTestHouse4resultsincludingair exchangerates,ozone


Table9.32. TestHouse 4AER/ODRJanuary715:48,Test Conditions. ....................... 205Table9.33. TestHouse 4OERJanuary7‐815:48,TestConditions................................ 206Table9.34. TestHouse 4OERJanuary817:10, Test Conditions. ................................... 207Table9.35. SummaryofTestHouse5resultsincludingair exchangerates,ozone


Table9.36. TestHouse 5AER/ODR/OERJanuary10,2013 9:21,Test Conditions.214Table9.37. TestHouse 5OERJanuary11 9:10, Test Conditions. ................................... 214Table9.38, SummaryofTestHouse6resultsincludingair exchangerates,ozone


Table9.39. TestHouse 6AER/ODR/OERJanuary12,2013 9:21,Test Conditions.221Table9.40. TestHouse 6OERJanuary12‐13 20:00,Test Conditions. ......................... 221Table9.41. TestHouse 6OERJanuary13 10:17,Test Conditions. ................................ 222Table9.42. SummaryofCommercialTest resultsincludingair exchangerates,ozone


Table9.43. CommercialTestAER/ODR/OERJanuary14, 20139:35, Test Conditions............................................................................................................................................................. 228

Table9.44. TulsaTest HouseDataCalculated Valuesand Uncertainty Estimates.. 229Table9.45. California MayField TestCalculatedValuesandUncertaintyEstimates.

............................................................................................................................................................ 235Table9.46. CaliforniaJanuaryFieldTests CalculatedValuesand Uncertainty

Estimates........................................................................................................................................ 237

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Abstract

Theozone emission rateandtheincrease inindoorozone concentrations fromtheuseofelectricallyconnectedin‐ductaircleanerswerestudied inthisresearch.Electrically connectedin‐ductaircleaners(eightmodels)were testedon alaboratorytestapparatususingaStandardTestMethodthatwas developedforthisproject.Emissionratesrangedfrom lessthanthemethodquantificationlimitof 2.3 mgh‐1 togreaterthan350mgh‐1.Withsomeexceptions, emission ratesweregenerallynotsensitivetoflowrateortemperature.Fieldtestsofelectricallyconnected deviceswerecompletedin7residentialbuildings(1 inTulsa,OK,6intheDavis/SacramentoareaofCalifornia)andoneCalifornia classroom.Theincrementalincreaseintheroomozoneconcentrationduetotheoperationofthesedevicesrangedfromundetectableto194 ppbwithdevicesoperating normally,whichisabovethecurrent Californialimitof50ppbsetforportableaircleaningdevices.Theoperationof oneunitin“shock” modeelevated themaximumand steady‐stateconcentrationatasupplyventto 508ppb.Estimatedemissionrates infieldbuildingsrangedfromundetectableto414mg h‐1.ForaStandard Californiahouse,modelanalysispredictsthatan emissionrateofapproximately 150 mgh‐1 wouldraisetheindoorconcentrationby about50ppb.Inan“At‐Risk‐House”modelanalysis,anemissionrateof 27to 55mgh‐1 canraisetheindoorozoneconcentrationby50ppb.BothStandardandAt‐Riskhomesimulationsassumethattheoutdoorozoneconcentrationiszero.Therefore,somein‐ductair cleanersgenerateozoneatratesthatcan increaseindoorconcentrations aboveacceptedmaximumlevels.

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Executive Summary

Introduction

Somecommerciallyavailabledevicesthatclaimtoremovecontaminantsfromindoorairuseelectrostaticfields,ultravioletlightandphotocatalysts. Assuch,theseair‐cleaning devicescan intentionallyorunintentionallygenerateozone.Ozoneisa Clean Air Actcriteriapollutant (NAAQS)anditsadversehealth effectsarewell established (USEPA,2007).Inindoorenvironments,ozonegeneratingaircleanerscanreduceairqualityandcanincrease indoor ozoneconcentrations aboveambient levelseven insmog‐proneareas. TheStateofCaliforniabansportableandstand‐aloneindooraircleaningdevicesto beusedin occupiedspaces thatcanincreaseozoneconcentrationsto50ppbormorewhen testedwith astandardizedmethod(UL867).In‐ductdevicesare not yetregulatedbecausetheexisting testmethodcannotadequatelyaccountforthe conditions thatexist in high‐flowduct environmentsandnoequivalenttestforsuchdeviceshas beendeveloped. Additionally,there islittlepubliclyavailabledataon theamountofozoneproducedbyin‐ductdevices. Thus,there isa need todevelopsuchamethodandtoevaluate in‐ductaircleanersfor theirpotentialtogenerateandincreaseindoorairconcentrationsofozone. Throughlaboratoryand fieldmeasurements, theresearch reported hereprovidesatestmethodandnecessarydatato supportinclusionofin‐duct aircleaners intotheCaliforniaAirResourcesBoardair cleaner regulation,if warranted. Thetwocentralobjectivesoftheproposedresearchwereto: 1)developandtestamethodofmeasuring theozoneemissionofin‐ductelectrically‐connected aircleaners(“device”)and2)obtainreal‐worlddataonozoneconcentration increasesdueto useofthesedevices in Californiabuildings.Twosecondaryobjectiveswere to3)applythemethodtoanumberof commerciallyavailableunitsin thelabtomeasure emission rates,and4)modelthe impactofin‐ductaircleaners inCaliforniabuildings. Methods

Thisresearchincludedlaboratory developmentofa test method and demonstrationtestapparatus,laboratorytestingofin‐ductaircleaners,fieldtestsofdevicesinhomesandonecommercialsite,andmodelsimulationsofindoor ozoneconcentrationsforCalifornia residences. Thetestmethodandtestapparatuswerebasedonthemass‐balanceprinciplethattheozoneemissionrateisthe air flowratemultipliedbythe increase in theozone concentrationacrossan in‐ductaircleaner,accountingforany reactivelossesofozonetothe surfacesof theapparatus.Themethodandapparatusweredesigned toaccommodatea wide varietyofdevices,andto testdevicesunder avarietyof flow,

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temperatureandhumidityconditionsthatareconsistent withconditionsintypical ductedheating,ventilationand air conditioning systems(HVAC).Twelvedevices(8models)weretested in thelaboratoryapparatususingthestandardmethod.Thesedevicesincludedgermicidalultravioletlights, ozonegenerators,photocatalyticoxidizers,andelectrostaticprecipitators.Thedevices tested werechosenbasedonasurveyofmanufacturers,installers, stakeholders,availability andfeedbackfromtheAirResourcesBoardandtheprojectadvisorycommittee. In‐ductair cleaners weretested in fieldlocationsin theDavis/Sacramentoregion ofCaliforniaandinTulsa,OK.Fieldresearchin Tulsadeveloped testmethodsandtestedseveraldevicesinstalled inanHVACsystemofahousetypical ofsmallCaliforniaresidences.InCaliforniasixaircleaners were testedinsix unoccupiedhouses;insomehouses,morethan onemodelofdevicewastested.Houseswereairedoutcompletelybeforebeingre‐occupied.Onecommercialaircleaner wastestedin a Californiaelementaryschool.Measurements included indoorandoutdoorozoneconcentrations(usingUVphotometricozoneanalyzers:2BTechmodel202andAPImodel400E),the incrementalincreasein the indoorozoneconcentrationduetodeviceoperation,the air exchangerate(CO2 tracerdecay)andtheozonedecayrate. Thedevice emissionratewasalsoestimatedbasedonthesemeasurements. Theimpact ofozoneemittingdevicesonthe indoorconcentrationofozonein Californiahomeswasestimatedusingstandardsingle and multi‐zonemassbalance models.Parametersforinclusion inthosemodelsweredetermined basedon Californiaresidentialbuildingstock(volume,surfacearea,air exchangerates, etc.)andprior researchregardingozone removalrates inbuildings. Theresultsfrommodelanalysisincluded1)steadystateroomozoneconcentrations asafunction ofbuildingvolume,reactivity, air exchangerates andother parameters, 2)dynamicozoneconcentrationsresulting fromHVACcyclingandoutdoorozoneinfiltrationand3)room‐to‐roomdifferences intheozoneconcentration.

Results

Thefollowingsummarizestheresultsofthisresearch. Objective 1. Develop and test a method of measuring the ozone emission rates for in‐duct electrically‐connected air cleaners

Thestandardtestmethod(STM)developedinthisresearchincludesspecificationsforapparatussizingandconfiguration,airflow ratesandmeasurementrequirementsforozone,temperature,humidity,electricalpower and flow rates. Thefundamentalbasisfor thetest methodisthattheozonemassemission rateisthe productoftheaverageozonemassconcentrationrise acrossthe aircleanerandthevolumetricflowrate.Theapparatusconsists offourmajorsections/functions:thetestsection wherethe aircleaner is locatedandwhereozoneismeasured;the

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treatment sectionwhereincoming orrecirculatedairiscleaned ofozoneandparticlesbeforeenteringtheapparatus;theflowgenerationsection whereairflow isgenerated(usuallywithvariablespeedfans);andan additionalsection,the contaminant and environmental variation section, which can be considered optional,whereozone,dust,moisture,and conditioningaregeneratedfor specificoptionaltests.Detailedreportingandcalculationproceduresareincludedinthetest method.Thestandarddescribesanexampleapparatusthatconformstotherequirements oftheSTM.Thisstandard apparatus wastested extensively. Thisapparatuswas determined to haveamethodquantification limit (MQL) of 2.3 mg of ozone per hour. Objective 2. Measure the incremental increase in the indoor ozone concentration due to the use of in‐duct electrically connected air cleaners in field homes. Fieldtestsofelectricallyconnecteddeviceswerecompletedin seven residentialbuildings(oneinTulsa, OK,six intheDavis/Sacramento areaof California).One commercialunitwastestedina classroom.Theincrementalincreaseintheroomozoneconcentrationduetotheoperationof thesedevicesrangedfrom undetectable to194ppbwhendevicesoperated normally.Operationof oneunitin“shock”mode elevatedthe concentrationat asupplyventto 508ppb.Twoelectrostatic precipitator devicesraisedthe indoorairconcentrationin the room(center)orreturngrill by5to22ppb.All otherdevicesusedanultravioletlight(germicidal/photocatalytic/ozoneoroxidant generation).Twomodelsincreased theozoneconcentrationinfieldresidences bygreater than50ppb.Both devicesareintentional ozonegenerators,basedonproductliterature.Combiningtheincrementalincrease inozoneat a returngrill withozonedecayrates inhomes,itwaspossibletoestimatetheozone emission ratesin‐situ. Theseemissionratesrangedfromundetectabletogreaterthan400mgh‐1.Emissionratesfromseveraldevicesappearedtodiminishovertime,suggesting that“break‐in”occursearlyon.Twodevices,onean explicitozonegenerator,alsoexhibitederraticemissionrates(sometimesnotworkingatall)suggestingpoormanufacturingquality. Objective 3. Apply the test method, developed to meet objective 1, to determine the ozone emission rate from commercially available in‐duct air cleaners.

AlistofdevicesanddevicetypestotestwasdevelopedprimarilythroughcontactwithCalifornia installers,discussionswithfederalandstate agencies, internetsearches fordevicesand contactwithmanufacturers.Sixclassesofdevicesthatcouldpotentiallygenerateozonewere identified:electrostatic precipitators, electronicallyenhancedfilters, ultravioletlightbulbs,photocatalyticoxidationsystems,dedicatedoxidantgenerators(ozone,hydroxylradical, hydroperoxideradical),andhybridsystems.The majorityof devicesinstalled wereofthe electrostaticprecipitatortype.Devicesthatusedultraviolet lightsweresecond.Alistofsevendevice typeswasdevelopedfortesting.Devicesfinallyselected fortesting includedelectrostaticprecipitators,ozoneandotheroxidant generators,germicidalultravioletlightand a photocatalyticoxidation system.

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Somedeviceshademissionratesat orbelowtheMQL.Thedevice withthehighestemission rate,approximately350 mgh‐1,wasanintentionalozonegeneratorthat usedanultravioletlightbulb for“aircleaning”.Threephotocatalyticdevicesofthesamemodelexhibited relativelylow,andconsistent,ozone emission rates.Most deviceswereinsensitivetoflow.One device (aircleanernumber6,anexplicitozone generator)exhibitedanincreasingozoneemissionrateastheair flowrateincreased. However,a seconddeviceofthesamemodelwasnotas sensitiveto flow.Anelectrostaticprecipitatorexhibitedhigher emissionratesatlowertemperatures. Simulatedandmeasuredindoorozoneconcentrationswereinreasonableagreement fordevicestested in both laboratoryandfieldsettings.By combining laboratorytested emissionratesand measured buildingparametersatfieldsites, indoorozoneconcentrationcould besimulatedusingthe steady‐stateindoorozoneconcentrationmodel.Measuredandestimatedozoneconcentrations werewithinafactorof 2formostdevices.Forthemodelthatexhibited the mosterratic emissionrates,thesimulatedconcentrationwaswithinafactorofabout3. Objective 4. Estimate, through building air quality simulation models, the indoor air concentration that could result from use of in‐duct air cleaners.

Insteady‐stateindoorozoneconcentrationsimulations,two“model”homeswere included.TheStandard Homewasbasedon California(andnationalwherenecessary) averagevaluesofbuildingvolumes,areas,airexchangerates,ozonepenetration, andozone decayrates. TheAt‐risk Homewasbased ona reasonablechoiceofparameters(suchassmallvolumeandlowozonereactivity)that,whencombined,maximizedtheresultingindoorozoneconcentration.Indoorozoneconcentrationsincreasealongwith emission rates,butdecline with increasing air exchange rates(in theabsenceofambientozone)andozonedecayrates.FortheStandardHome,theincrementalincreaseinindoorozoneconcentrationreaches50ppbwhentheemissionrateisabout150mgh‐1.Thesameconcentration isreachedintheAt‐riskHousefor anemissionrateofonlyabout 27mgh‐1.Theozoneconcentrationismore sensitive to airexchangerateinsmaller buildings.Infiltrationofambientozonecontributessomewhattoindoorconcentrations, dependingonthe magnitude ofair exchangerates, outdoorconcentrationsandthe deviceemission rates. A dynamic(time‐dependent) multi‐zonemodelfoundthatseparateroomscanhaveverydifferent, andelevated,indoorairconcentrationsevenwhenthe airhandlerisoff,butthedevice isoperating.For 100mgh‐1 devicestiedtotheoperationof theairhandlingsystem,themodelpredicts average indoor concentrationsranging from15‐20 ppbwhentheHVACsystemison20%ofthetimeand35‐50ppbforHVACthatison50%ofthetime. Theindoorozoneconcentrationthatresultsfrom usingthesedevicesincreaseswithincreasingemissionrate,andisgenerallyconsistentwith thevaluepredictedby applyingthe mass‐balancemodeltospecific fieldsites.

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Conclusions

Somein‐ductaircleanersgenerateozoneatratesthatcanincreaseindoorconcentrationsaboveacceptedmaximumlevels.Modelanalysissuggeststhatin‐ductdeviceswithemissionratesgreaterthan about30mgh‐1 canincreaseindoorozoneconcentrations by50ppbor moreinatleastsomeCaliforniahomes.Fourdeviceswere observed toemitozoneatorabovethis emissionratein laboratoryandfieldtests.Twodeviceslabeledas“ozone generators” were observedtoincreaseindoorconcentrations by greaterthan50ppbinfield tests. Evendevices thatmakeno claimsaboutemitting ozonehaveemission rateshighenoughtotheoreticallyincreaseindoorconcentrationsabove50ppbinwell‐sealed,small,low‐reactivityhomes. Overall,thisresearchtellsaconsistentstory: in‐ductdevicesthatemitozoneinbuildingshavethepotentialto raiseindoorozoneconcentrationsbeyondcurrentCalifornialimits.Alaboratory test methodgeneratesozoneemission rates that can, reasonably,beincorporated intomassbalancemodelstopredict the potentialincrease in indoorozoneconcentrations.Therefore it ispossibletoestablishalimit ontheemissionrateofin‐duct aircleanersiftheStateofCaliforniasetsaconcentrationlimitandestablisheswhattypeofbuildingandconditionstheybelieveshouldbeusedforestimatingan emissionratethat is sufficientlyprotectiveofCalifornians. Wedonotrecommendthatfurther researchtakeplaceto determine ifthesekinds ofdevicescanincrease ozoneconcentrationsinCalifornia homes.Webelieve itis clearlyestablishedthat increasing ozoneemissionsincreasesozoneconcentrationsandthat theresulting range of indoorconcentrationscanbepredicted,withinreason, for Californiabuildingtypes.However, wedorecommend thattheStateofCalifornia makean efforttobetterunderstandthemarketofthese devicesanddetermine thepotential fortheirinstallation, especiallyin smallerhomesthathavelowairexchangerates.Thiswillbekeyto establishingrisktoCaliforniaresidents.Wefurtherrecommendthatmoretestingbe performed onmultiple devicesofthesamemodel(consistencyinmanufacture);thattheybetestedunder adverseconditions(e.g.veryhigh temperaturesinatticspaces);that theybe tested forerraticbehaviorandconsideradditions totheStandardTestMethod toaddress erraticmodels,andthattheybe testedoverlongperiodsinfieldsites toestablish howage,temperature, humidityandreal‐worldsoilingaffectsperformance.

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1 Introduction

In2007,theARBadoptedaregulationthatlimitsozoneemissions fromindoor aircleaningdevices.Aircleanersphysicallyintegratedwithinacentral ventilationsystem,called“in‐duct”aircleaners,were exemptedfromtherequirementsofARB’sregulationbecausenosuitabletest methodwasavailableformeasuringozone emissions fromsuchdevices, and fewdatawereavailableontheirozoneemissions tosupportregulation.However, thereareanumberofin‐duct intentionalozonegeneratorsaswellasin‐ductelectrostatic,ionizer,electrically‐enhancedmedia(activelyconnectedtoAC/DCsource),andultravioletaircleanersknowntoemitozone that are marketed in California. There is reason tobelievethatsomeofthese maygeneratesignificantamounts ofozoneand/orozonereaction byproductssuchasformaldehyde. Thecurrent Californiaregulation reliesonthetestmethoddescribedinSection40ofUnderwritersLaboratoryStandard867(UL867)tocertifycomplianceofportableindooraircleaningdeviceswith the0.050ppmemission concentrationlimit.However,UL867does notinclude a suitabletestmethod formeasuringozone emissionsfromin‐ductdevices.

1.1 Health EffectsThepresenceofozoneintheindoorenvironmenthasserioushealthconsequencesinadditiontodetrimentaleffectsonbuildingandhouseholdmaterials.Humanexposuretoozone,evenatrelativelylowlevels,hasbeen foundtocauseavarietyof adversehealtheffectsincluding decreases inpulmonaryfunctionand increases inreported symptomssuchasheadacheandcough(USEPA,2007).OzoneconcentrationsbelowtheNationalAmbientAirQualityStandard (NAAQS)havebeenassociatedwithwheezingand difficultybreathingamonginfants,particularlythosewhosemothershavephysician‐diagnosedasthma(Trischeet al.2006).Short‐term(Belletal.,2006) exposure to increasedozoneconcentrationshasalsobeen linkedtoprematuremortality.

1.2 Indoor ozone concentrations and sourcesConcentrationsofozoneintheindoorenvironmentvaryasafunctionofoutdoorcontributionsandindoorsources.Indoor/outdoorratiosthatresultfromoutdoorozonecontributionsalonerange from0.05intightlysealedbuildings(orthoseutilizingcharcoalfilters),to0.85inbuildings withvery highairexchangerates. Excludingextremes, theI/Oratioismoreofteninthe rangeof 0.2‐0.7(Weschler,2000).Copiers,laserprinters,electronicaircleaners andozonegeneratorscanactasasourceofindoorozonewith emissionratesrangingfrom0.1to220mgh‐1(Brittiganetal.,2006; Mullenetal.,2005).Thisrange iscomparabletooutdoorair

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asasource ofozonewhichcanriseto~100 mgh‐1 foratypicalresidenceonahighlypollutedday. Indoorsourcesofozonehavebecomeaconcernfor theindirect effectsofozonechemistryas wellasthedirecteffectofexposingoccupantsto moreozone.Ozonereactionswithterpenoidsreleased bycleaners (Nazaroff andWeschler,2004),airfreshenersandpersonalcareproducts(Corsietal.,2007)generaterespiratoryirritants(Anderson et al.,2007) andlow‐volatilityspeciesthatcondense tosubstantially increase sub‐micron sized aerosol mass concentrations (Hubbard et al., 2005;Waringet al.,2008;Weschler andShields,1999). Ozone reactionswithindoorsurfacessuchascarpet(Morrisonand Nazaroff,2002),ducts(Morrisonetal.,1998),paintedwalls(Reissetal.,1995)andsoiledsurfaces(WangandMorrison, 2006)generate volatile aldehydes,carboxylicacidsand ketones.Incertainsettings,much oftheindoorozoneconversionratesareduetoreactions withskinoilsthatcoathumans,theirclothingandothersurfaces(Colemanetal., 2008;Weschleretal.,2007).Reactionstaking placeon(Pandrangi andMorrison, 2008) ornearthebody(Corsietal.,2007)increaseproductandaerosolconcentrationsinthebreathingzone(Rimetal.,2009), relative totherestof thebuildingspace. Useofozone emittingappliancesincreasetheindoorconcentrationsofallofthese reactionproducts.Portableiongenerators,whichoperateonthesameprinciple asin‐ductelectrostaticprecipitators andgenerate ozoneas a byproduct,havebeenshowntoincrease aerosolconcentrationswhenusedin thepresence ofterpenes(Waringet al.,2008;WaringandSiegel,2011)fromconsumerproductssuchasairfresheners. In‐ductelectronicaircleanerscan generate ozone,butonlya handfulof experimentalobservationsexist.Bowser(1999)studied 15homes within‐duct“electronicaircleaners”(typenot specified,butprobablyplate‐and‐wireelectrostaticprecipitators)and observedozoneemission rates rangingfrom13 to 62mgh‐1.Theyobservedindoorconcentrationsofozone,butwerenotabletoascribewhatfractionalincrease wasduetodeviceemissions.Hanley etal.(1995)measuredanemission rate at10mgh‐1 forasingle electrostaticprecipitator.Vineretal.(1992)studiedthreecommercialin‐ductelectrostaticprecipitatorsandobservedozoneemissionratesrangingfrom 20‐30mgh‐1.A25mgh‐1 emission rate isequivalenttoinfiltrationof outdoorozoneatthefederalregulatory limit(75ppb) inatypical house(300m3)withatypicalair exchangerate (0.56).Therefore, anin‐ductaircleanercancontributesubstantiallytotheindoor ozoneconcentration ofa typicalhome.Emmerich andNabinger etal.(2000)used twoin‐ductaircleaners(electrostaticprecipitators)inafullscale“test house”.The resultingindoorconcentrationfromuseofonedeviceasrecommendedroseashighas 200ppbatanairexchange rateof0.2 h‐1 withanoutdoorconcentrationequalto22ppb.Aseconddevice testeddidnotgeneratemeasurableemissionsofozonebutalsoexhibitedverylowparticlefiltrationefficiency.Inasinglehome,use ofan electronicair cleaner(plateand wire electrostaticprecipitator)increasedindoorconcentrations

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ofozonebyapproximately10ppbovernormalbackgroundlevels (CMHC,2003).Theydid notreport an emission rate. Somedataexistsfortheimpact ofoperatingconditionsonozoneemissionrates.Masonet al.(2000)observed that ozoneemissionrates fromelectrostatic aircleanersdecreasedbyabout30%asRHincreasedfrom30%to70 %.Vineretal.(1992)did notobserveastrong effectofhumidityon the ozone outputofthreeelectrostaticprecipitators,buttheyascribedthistothelimitedsetofdata. Amuchstrongereffectonozone productionwasduetoaccumulationofdustontheelectrodeobservedby Dorseyand Davidson(1994).Usingtheair cleanertofilterArizonaroad dust,they observeda 4.6foldincrease inozoneemissionrates aselectrodes becamesoiledover a 1 weekperiod.Theyverifiedthat accumulation ofadielectricmaterial(dust)tothecoronadischargewireincreasesthecoronacurrent.Inlaboratorytestingofaplate and wire electrostaticprecipitator,HuangandChen(2001)foundthatsoilingledtodecreasedozoneemissionsbecauseofdecreasedcoronacurrent.Bowser(1999)foundnoconsistenttrend inozone emissionratesandthe extentofsoilingon15electrostaticprecipitators in homes.Rapiddegradationoffiltrationefficiency wasobservedinseveralhomesduetoin‐usesoiling(CHMC,2007) butozonewasnotmeasuredinthisstudy. Phillipsetal.(1999)observed atemporaryincrease inozoneemissionrate fromapersonalair purifier(negativeion generator)whendustwasintentionallyappliedtoelectrodes.Inastudyofcoronachangesunderrealisticconditions, Hanley etal.(2002)found thatcorona enhancedsilicondioxidevapordeposition,not particlesoiling,caused coronaintensity(andfiltration efficiency)todecrease.Coronacurrentislinearlyproportionaltoozoneproduction rates(Vineretal.,1992).Interestingly,themanufacturersofthehigh‐emittingdevicetestedbyEmmerichandNabinger(2000)claimedthatozoneemissionrateswouldactually diminish withtime/operation. Theimpact ofsoilingon ozonegenerationisa functionof amountandcompositionofsoilingparticles, as wellashowcoronavoltageis regulated(HuangandChen,2001).UL standard867includes anappliancerun‐in(break in period)toremoveresidualoil frommanufacturing. Giventhatsoilinganddepositscaninfluenceozone generation rates, thelengthof the run‐inperiodcouldimpact test resultswheredevicesare coatedwithdifferingtypesandamountsofmachine oils.Therefore,residualoils,soilingor chemicalvapordepositionincommercialor homedevicescouldaffectozonegenerationrates,andpossiblyozone‐dustchemistry,andmeritsmorestudy. Otherfactorsthatmay increaseozoneemission includecoronavoltageandtemperature.Liuetal. (2000)foundthata 50%increase involtagecausedan eight‐foldincreaseinozoneemissionrateinaprototypein‐ductelectrostaticprecipitator.Voltagevariationswithdevicescanbecausedbymanufacturing defectsor byextensivesoiling.Ozoneemissions alsoincreasedwithincreasedtemperature, althoughamuchsmallereffect was reportedandthetemperature rangeconsideredincludedmuchlargerthantypical indoortemperatures.Improperinstallationcanimpactremovalefficiencyandmay influence ozoneemissionrates. A “swimming

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poolodor”wasdetected,andascribedtohighozoneemissions, fromadevicethatmayhavehadfaultyelectricalconnectionsafter cleaning andreseating(CMHC, 2007).Airvelocityisgenerally observed tohavelittleeffect onemissionratesbecausecoronacurrentislargelyunaffected(Vineretal., 1992;Bowser,1999). Thecurrent Californiaregulation reliesonthetestmethoddescribedinSection40ofUnderwritersLaboratoryStandard867(UL867)tocertifycomplianceofportableindooraircleaningdeviceswith the0.050ppmemission concentrationlimit.The revisedU.L. Standard867states thataportableaircleaningdevicemustnotproduceanozoneconcentration exceeding50ppbbyvolumewhen tested asdescribedinSection40.Thefinalintentofthe Standardisto limitsituationsin homeswherethesole useofanaircleaningdevice resultedin concentrations>50ppb,ignoringotherinfluences.WhiletheexistingUL 867 standardisbased onthe50ppbconcentrationlimit,thetestprotocolsaredesigned sothat50ppbcorrespondstoanexplicitsource emissionrateequalto3.6to 4.1mgh‐1 (dependingonchambervolume)Theresulting concentrationinthetestistherefore proportionaltotheemissionrate. Aswritten, UL867appliesonlytoportableindoor aircleaningdevices anddoesnot includeasuitabletestmethodformeasuringozoneemissionsfromin‐ductdevices. Giventhepaucityofdataonthe operationofin‐ductelectronicaircleaners,measurementofemissionratesin modern devices is needed. Further,ifamaximumozoneemissionratestandardis promulgated,anaccurate,readilytransferrabletestmethodforemissionratesisalsoneeded.Finally,theimpactoftheir operationontheresultingozoneconcentrationinCaliforniahomeswill help ARBdetermineifandatwhatlevelanemissionratestandardis necessary.TobetterunderstandtheimpactofthesedevicesinCalifornia,thisprojectcompletedthefollowingtasks:developedalistofdevicestotest,developedalaboratorytestmethodandtesteddevicesusingthatmethod,measuredtheincreaseinindoorozoneduetouseofthesedevicesin atfieldsites and estimatedtheimpactofthesedevicesonsmallCaliforniahomesusingmassbalancemodels. 1.3 Development of list of devices to testInthistask, theprincipalinvestigators(PIs)identifiedalistofin‐ductelectronicaircleanersandtheirpotentialuse in California. Theanalysiswasperformedthroughdirectcontact(phoneandemail) withmanufacturers,distributorsandinstallers,aswellasothermeanswherepossible(internet searches). Thecentralgoalofthisanalysiswas torapidly assessimportanttechnologiesusedfor in‐ductaircleaningthatemitozone.There are several known classesofexistingtechnologiesthatemitozoneincluding: electrostaticprecipitators(Vineret al.,1992),ultravioletlightsthatemitator below254nm,dedicatedozonegenerators,andelectrically‐enhanced filtration media(Agranovskiet al.,2006).Thesetechnologies,as wellasotherpotentialozone‐emittingtechnologieswereidentified.

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1.4 Laboratory test method development and device testingThecentralgoalwastodevelop arobustlaboratorytest method tomeasurethe ozoneemissionrate(dimensionsofmass/time,e.g.,mgh‐1)ofin‐ductaircleaners.Theemissionrateisa characteristicoftheaircleanerandemissions ratedatathatwhencombinedwithfielddatacollectedinTasks3andTask4shouldallowforanassessmentoftheimpactofanin‐ductozone‐emittingaircleanerinatypicalCaliforniahome. Indevelopingthistest method,werecognized severalmethodologicalissueswith assessingtheozoneemissionrate,including:

Evenatrelativelyhighemission rates,ozoneconcentrationscanbedilutedbelowthesensitivityofmostozoneanalyzers attypicalHVAC air flowrates.

Ozoneemissionmaynotbeuniformacrossthedevicecross‐section. Ozoneemissionmaybeafunction ofenvironmentalparameters

(temperature,relative humidity, airvelocity)andcleanliness oftheozone generating partofthe device(i.e., corona,pin ionizers,UV bulb).

Emittedozonemaybeconsumedby reactionswithdepositedmaterialor withotherpartsofthe air cleaningdevice orHVACsystem.Thesereactionsareundesirablebecauseofthepotentialforproductionofbyproducts. Ifsuchreactionstakeplacebetweenthedeviceandadownstreamozonemeasurementpoint, thantheywillcausetheozoneemissionrate tobeunderestimated.

Theproposedlaboratorytechniqueexplored theseissues andresultedinastandardtestmethod forascertainingozone emission rate.

1.5 Field testing

TheobjectiveofinitialfieldresearchinTulsawastodevelop protocolsandidentify relevantparameterstoguidethe fieldstudiesofCaliforniahomes.Inaddition,thesefieldexperimentsallowedustocomparetheperformanceofseveralunitsinthefieldthat had alreadybeen testedinthelab.TheprimaryobjectiveoftheCaliforniafieldtests wastomeasuretheincreaseinozoneconcentration thatresultsfromtheoperationofin‐ductozone‐emittingdevicesinunoccupiedCalifornia buildings.Estimatesofthedeviceemission rateswerealsoobtained.Insomecases,theinfluenceofenvironmentalconditionsonconcentrationandemissionrateswasidentified. 1.6 Building simulationsTheobjectiveofthistaskwastoperformarangeofbuildingsimulationstopredicttheindoorozoneconcentrationthatresultsfromoperatingin‐ductaircleaners.Emissionsfromozone‐emittingin‐ductdevicesaredilutedbyairexchangeandattenuated byreactionswithgases(e.g.NOandterpenes),ductworkandotherindoorsurfaces.Therefore,the resultingconcentrationat asupplyventorinthe occupiedspacevariesby buildingandtemporallychangingconditions.Using simple

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butrealistic models,theozone concentrations thatresultfrom useofthesedevicescanbeestimatedrelativetospecificbuildingconfigurationsandconditions.

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2 Materials and methodsThroughout theremainderofthis report,theconcentrationofozone isreportedinunitsofpartsperbillion(ppb) or microgramspercubicmeter (g m‐3).Theconversion at25ºC:multiplyconcentration in unitsofppbby1.96(or~2)toconverttoconcentrationinunitsof gm‐3. 2.1 Candidate device survey

Task1of In‐duct air cleaning devices: Ozone emission rates and test methodologyrequiredthe developmentofalistofin‐ductelectronicaircleaners thatmayemit ozoneandarelikely(orpotentially)installed in Californiabuildings.Theanalysiswasperformedthroughdirectcontact(phoneandemail)withmanufacturers,distributorsandinstallers,aswellasothermeanswhere possible(internetsearches). 2.1.1 Candidate device survey in California residences

Togenerateareasonableestimateofcandidatedevicesthatmay be installedinCaliforniahomes,wecontacted72HVACinstallersinBakersfield,Fresno,LosAngeles,Riverside,Sacramento, SanDiego,SanJoseandStockton.Of the72,wewereabletogetamanagerorinstallertoanswersomeofourquestionsregardingthetypesof devices installed.

‐ Weidentifiedourselvesandrequestedthattheyshare thefollowinginformationwithus:

o Verifythattheydoresidential installationofaircleaningequipment Ifonlycommercialdiscontinuesurvey

o Dotheyinstallelectronicin‐duct aircleaners o Whatbrandsdotheysell o Whichmodel/brandsaremostpopularoraremostlikelytobe

installedbasedontheir experience. o Whichdistributorstheyworkwith

2.1.2 Contact with agencies

Wecontactedagenciesandorganizationsthatwefeltwouldhave alreadyspentsometimeconsideringin‐ductdevicesandwouldhavealreadydevelopedopinionsonwhatkindsofdevicestheywouldliketested.Agencies andorganizationscontactedwereUnderwriters Laboratory, the ConsumerProduct Safety Commission,theEnvironmentalProtection Agency,HealthCanada and theNationalResearchCouncilofCanada.

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2.1.3 Recommendations for device testing

InTask2,aminimumofsevendevicesweretobetested.Based onthe marketsurveyresultsandfeedbackfrom agencies,organizations,theproject advisorygroupandstaffoftheAirResourcesBoard,wedevelopedalist ofpossibledevicestoacquireandtest.Itisnotpossibletotest alltechnologies andstyles within aspecifictechnologyandthismayinclude testsofdifferentdevicesofsamemodel.Given thattheprojectreliesheavilyondonateddevices, wedesignatedpreferredstylesandmanufacturersratherthanspecific models. 2.2 Laboratory test method development and device testing

InTask2of In‐duct air cleaning devices: Ozone emission rates and test methodologythegoalwastodevelopastandardforthelaboratorymeasurementofozoneemission ratesfromelectrically‐connectedin‐ductaircleaners andtotestaircleanersusingthedevelopedstandard.

2.2.1 Standard Test Method developmentThissectionisorganizedintoa descriptionofthemotivation, methodology,andthoughtprocessthatwasusedfor designingthefinalversionofthe StandardTestMethod,theapparatusthatwasdevelopedforthestandardtesting. Themotivationforthestandard arisesfromthefact that most standardsforozoneemission fromaircleanersare intended forportableaircleanersthatoperateinalowflowcondition.Thesestandardsalsoexplicitlyexcludein‐ductdevices(i.e., UL867).Incontrast,in‐ductaircleanersareusuallydesignedtocycleonwiththeoperationoftheHVACsystemand thuscanhaveveryhighflowthroughthem.Thesehighflowscauseadilutionintheozoneconcentration. Figure2.1showsthetheoretical concentrationrise acrossanozoneemittingdevice asafunctionofflow forfiveemissionratesforozone. Attypicalresidentialflowsof1,600‐3,200m3h‐1,ozoneconcentrationrisesaretoosmalltomeasureaccuratelyfora5mgh‐1 ozone generator(notethatsuchadevicewouldexceedtheallowableeffective emissionrateof3.9 mgh‐1 foraportableair cleaner in ARB2007) andconsiderablyless than10ppbforanaircleanerwitha25mgh‐1 emissionrate(anaircleanerthatemits morethansixtimestheallowablelimitinARB2007).Onesolutionistotestin‐duct devicesin a staticchambertest accordingto UL867orsimilar.Althoughconceptuallysimple,thishas severaldrawbacks,including:

Someaircleanersmayemitdifferentamountsofozonewhenthey areoperatingatlowflowthenathighflow.Astatictestmayoverestimateorunderestimate the ozone emission rate when operating in a duct as intended.

Somein‐ductaircleanershavea flowswitchandcanonlyemit ozonewhentheyhaveflowoverthem.Itisunclearwhetherbypassingthesedeviceswouldalsoaltertheoperationofthedevice.

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:g: 30 .3, Q) (/)

·;::

C 0

~ 20 c Q) (.) C 0 ()

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-

E = 25 mg h·1

E = 20 mg h·1

E = 15 mg h·1

E = 10 mg h·1

E = 5 mg h·1

0-----------------------------------< 500 1000 1500 2000 2500 3000

Flow (m3 h·1)

Somein‐ductaircleanershaveanozonecontroldevice(i.e.,activated carbonoracatalyst).Thesedevicesarebesttested atrealistic flowrates as theymightconsumemoreorlessozoneatdifferentflowrates.

Ingeneral,itisappropriatetotestdevicesat asrealisticandrepeatableconditionsaspossibleandthustheneedforarobustin‐ducttestmethod.

Figure 2.1. Concentration rise as a function of flow for in‐duct air cleaners with different emission rates.

2.2.1.1 Basis of standard and apparatusTheozoneemissionrateofadeviceisaproductoftheozoneconcentrationriseacrossthedevice andtheflowgoingthroughthedevice. Anystandardwillhavetohavehigh‐qualitymeasurementsofbothofthesequantities.A guidingprinciplefortheapparatusandtest methodwasthatthestandardshouldstrikea balancebetweentechnicalaccuracyandbeing easy to followandapply. Thisbalanceisnecessarytoachieve eventualadoptionofanystandard.Thefollowingsectiondescribesthekeydecisionsthat weremade indesigningtheapparatusandtest‐method. Test duct material: Ozoneischemicallyreactiveandatest‐ductthatconsumesozonecouldaffectthemeasuredozone riseacrossanaircleaner.Stainless steelwasselected as thematerialfortheapparatus.Becauseofthesizeofthetestduct(describedinmoredetailbelow),usingallstainlesssteel wouldbeprohibitivefromabudgetary standpoint andthus justthesectionoftheductcontaining theaircleaner and ozonemeasurementapparatuswasmadeof stainlesssteeland the restoftheductwasmadewithless expensivegalvanizedsteel.

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Test duct configuration: Generallytestductsareeitheropen‐loop(singlepass)orclosed‐loop(multiplepass).Openloopsystemsaregenerallysimplerbutalsocanrequireaconsiderable energyexpenditureto maintain environmentalconditionsintheductair.Thestandardallowseitherconfiguration,butforthepurposesofstandarddevelopment a closedloopsystemwasselectedsothat the airconditions couldbechanged if needed.Asecondconfigurationdecisionis the physicalshapeoftheduct.Open‐loopsystemscan bestraightducts,butthisrequiresalargeamountoffloorspace.Afloor‐spaceefficientconfiguration isU‐shaped(open‐loop)or oval(closed‐loop)andthelatterwasselectedfor thetest apparatus. Test duct size:Aductcross‐sectionof60cm ×60cmwasselectedtoaccommodateallsizesofaircleaners. Thisisconsistentwith manyfilter‐testingapparatuses(e.g.,ASHRAEStandard52.2).Theduct lengthwasdrivenbytheneed to haveadequatemixingbetweenozoneemissionand measurementanduniformflow inthetestsection. Ageneralrule ofthumbisthat5‐7ductdiameters(3‐4mgiventhecrosssection above)are neededafter everychange intheduct (i.e., abend,anemissionsource,etc.)andthatgradualchanges(suchasawide‐radiuscurve)arepreferabletoabruptchanges.For thisreason,aswellasthephysicalspacelimitations inthelaboratory, theductwasspecifiedtobe9mlong.Thisallowedforadequatespaceafterthemajorbendsintheoval,a2mlongtestsection,and spacefor mixingaftertheaircleaner. Flow generation:Residentialsystemsencounter awiderangeofairflowrates. Theruleofthumbintheairconditioningindustryisthat400 CFM (680m3h‐1)offlow areneeded foreveryton ofairconditioning. Typicalresidentialairconditioningsystemsrangefrom1‐5tons.Newerhomesmayalsohaveanoutdoorintake forventilation airandwhentheairconditionerorfurnaceis not needed, amuch smallerflow(assmall as85m3h‐1)maybeused.Thustheidealapparatuscould accommodatea wide rangeof flowrates.Intertwinedwiththeissueofflowrangeisaccuratemeasurementoftheflow rate andthisissueisdiscussedbelow. Forthetest apparatus,twostandard5‐tonresidentialindoorairhandlerunitswereselected.Bothunitsareratedtobeabletoachieve3400 m3h‐1 inatypicalresidential system,althoughit wasanticipated theresultingflowratewouldbelowerduetothelarge pressuredropofthetestapparatuscomponents.Eachunitwasconnectedtoavariablefrequencydrive(VFD)thatallowed continuousadjustmentfrom0%tofullpower.Twofanswereselectedasthisgenerallyimprovesairflowuniformity.Honeycombflowstraightenerswere usedin three locationsintheducttofurther improveuniformity.Ultimatelythe fansworkingtogetherat fullpowerproducedapproximately2500m3h‐1 (withsomevariationbasedonthe ageoftheHEPAfilter andtheparticularaircleanerbeing tested).Weconsidered goingtoahigherflowrate fan,but severalissues ledusawayfromthis decision including

Noiseconsiderations: verypowerfulfansare veryloudandthe safety ofpersonalin thelaboratory(includingthoseworkingonotherprojects)wouldhavebeen impacted

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Heatgeneration: Largerfansconsumemoreelectricityandgenerate moreheat.Wewereconcernedaboutheatgenerationintheductaffectingozoneemission results.

Apparatus airleakage: alarger fan (especially onewiththemotorexternaltotheduct)wouldhaveledtomuch higherairleakagefromthesystemwhich mayhaveaffectedtheresultsas wellasemittedozoneintothe lab

Budgetarylimitations: a new fanwouldhaverequiredadditional electricalworkthat wouldhaveexceeded thebudgetfortheapparatus

Control:FindingaVFDthatwould controlalargefanoverthe entire rangewouldhavecompoundedthebudgetaryissues (andmaynothavebeen available).

Air Cleaning: Bothopen‐loopandclosed‐loopsystemsrequireozonetreatmentbecauseofrelease into thelab orcontaminationofemissionresults. Activatedcarbonwas selected for thispurposebecauseofitsdemonstratedtrackrecordandthelarge numbersoffiltersavailableonthemarketplace. The teststandardallowsanyozoneremovaldevicethatmeetsthecriterioninthestandard.AHEPAfilterwasselectedtoavoidcontaminationoftheaircleaners.TheHEPAfilterwasthelargestpressuredropinthesystemandthuswasthelargestlimitation on overall flow. Ozone measurement: Thereareseveralconsiderations forachievinghigh‐qualityozone measurementincluding the accuracy and response time of theozone analyzer, therepresentativeness ofozone samplingacrosstheductcross section,andthedesignoftheofthesamplingsystem.Becauseoftheimportanceofmeasuringlowozoneconcentrations, thestandard requiresa researchgradeozone analyzer (definedas anaccuracy oflessthan2%or2ppb)andthereare atleastthree USmanufacturerswhomakeadevice thatcouldworkforthestandard. Inaddition tothetest ductitself,this willbeamajorbudgetaryitemfor anyonewhowantstoimplement thestandard. Toachieve arepresentative ozone sample,asamplinggrid wasdesigned.Thesamplinggrid,illustratedinFigure2.2,consistsofthree verticalstainlesssteelrods,55cminlengthwitha 6mmouterdiameterand1.5mmwallthickness.Five 1mmdiameterholesweredrilled12cm aparton eachofthethreerods, tomeasureanaverageozoneconcentrationovertheentirecrosssection oftheduct.Thethreerodsarespacedevenlyacrossthe ductwithoneinserted atthe centerlineof theductandtheothertwo20cmon eithersideof center.ASwagelokcapisattachedtoeachrodon theend insideoftheduct.Therodsare eachheld inplace within theductwitha Swagelokbulkheadunion.Thesegmentsofthe sampling gridoutsideoftheductareacombinationofthreeshort6mmverticalstainlesssteelrodsand twohorizontal pieces,connectedbySwagelokunions.Fromthetopofthesampling grid,6mmTeflontubingconnectsthesamplinggridto remainderofthesamplingsystem.

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t grid used to measure ozone upstream and dow Figure 2.2. Ozone sampling grid used to measure ozone upstream and downstream of air cleaner

Oneofthekeyconsiderations ina testmethod thatinvolvestwomeasurementpoints(forexample,upstreamanddownstreamozoneconcentrations)iswhethertorequiretwo measurementdevices orasingle device with switchingvalve.Thestandardallowsbothpathways(as longascertainqualification criteriacanbemet),butweassessedthat thecostandaddedcomplexityofasecond analyzer,especiallywhenozoneconcentrationsarelow,exceededthebenefits.Inordertouseasinglemonitorto analyze boththeupstreamanddownstreamozoneconcentrations, twoOmega2‐wayGeneral PurposeSolenoidValves(Normally ClosedModelNo.SV125;NormallyOpenModel No.SV133)wereused toenableswitchingback andforthbetweenupstreamand downstream sampling.AnOmegaProgrammable TimingController(ModelNo.PTC‐15)controlsthesevalves,controllingwhethertheozonemonitoris analyzingupstreamordownstreamconcentrations. Airflow measurement: ManyteststandardsthatinvolveflowinaductrequireASMEflownozzlesforflowmeasurement.Thistypeofflowmeasurementapproachpresented twoproblemsfortheductapparatus:thepressuredropofrelevantflownozzlesare verylargeandwouldhavefurther diminished maximumflowandthereareveryfewflownozzlesthathavehighaccuracyovertherangeofflowsneededinthetest apparatus.In thetest apparatus, a flow station is locatedpasttheoutletofthesecond fan. Theflow station (ShortridgeInstruments,Inc., VelGrid)isasquare,16point, facevelocity grid.The pressuredifferenceismeasuredthroughthe velocitygridbyusinganEnergy ConservatoryDG‐700digitalmanometer.The flowstationwas calibrated withanEnergyConservatory TrueFlowPlate. Ifamorepowerfulfanwasavailableinthesystem,adecisiontouseaflownozzle(ormultipleflownozzles)mayhavebeenmade asthisapproachwould havehigherflow measurementaccuracy. However,theuncertaintyin emissionratemeasurements

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formostdevicestestedinthis projectwasdrivenbyuncertaintyintheozone concentrationmeasurement,not flowrate. Other apparatus design considerations:Theeaseofchangingaircleanersfor testingisimportantforfacilitatingmorerapidtesting.Theaircleanertestsectionhada55cm×30cmremovablegasketedpanelthatcouldbereplacedwith apanelwitha holecutforeachaircleaner.Thus,eachaircleanercouldbe installedinapanelandboltedontotheaircleanerductasneededfortesting.Five panelswere needed toaccommodatethe aircleanerstestedinthisreport.Airleakage in thetestductcouldleadtoozoneemissionintothelaboratoryspaceand/orinaccurateemissionrateresults.Allsectionsofthe test ductweregasketedwith neoprene gasketing andtheductgapswerealsotapedwithfoiltapesuchthatthefoil side of the tape wasexposedtotheairflow.Forsafetyreasons,bothfanshadinterlockssuchthatthefanwouldnotenergizeiftheairhandlercabinetwasopen.Anadditionalsafetyconcernhadtodowith operatorexposuretoUVlightfromsome oftheaircleaners andfor this reason, a pressure switchwasplacedonthedoortotheapparatusrequiringittobeclosedforthepowertotheaircleanertobeenergized. Aschematicoftheapparatusfrom theaircleaneraccessside(airflow iscounter‐clockwise)isshownbelowinFigure2.3andaphotographofthe fanaccessside(airflowisclockwise)isshownbelowinFigure 2.4.

Activated Carbon Downstream Upstream HEPA Sampling Sampling Filter

Air Cleaner

Air Handling Air Handling Unit #1 Air Flow Unit #2

Flow Station

Figure 2.3. Schematic of test duct.

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Air Handling Units

Air Cleaner Test Section

Activated Carbon and HEPA Filters

Figure 2.4. Photograph of test apparatus

2.2.2 Device testingOncethestandardwas developed andpreliminary testing complete,thefinalstandardwasusedtotest12air cleaningdevices.Sincetheteststandardwas amajoroutcomeoftheproject,it isshownintheResultssectionof thisreport.Note however,thattheteststandardis the method withwhichthesedevicesweretested. Thedevices areshown belowinTable2.1wherethetechnologyisas describedbythemanufacturer.Mostofthedevicesgenerateozoneas a resultofhavingan ultravioletlamp,however,AirCleaner3generatesozoneasaresultofacorona discharge.

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Table 2.1. Air cleaning technologies tested in apparatus using the Standard Test Method

Air Cleaner Product Technology 1 Dust Free Bio Fighter Lightstick Ultraviolet light 2a Guardian Air by RGF #1 Photohydroionization 2b Guardian Air by RGF #2 Photohydroionization 2c Guardian Air by RGF #3 Photohydroionization 3 Honeywell F300 Electronic Air Cleaner Electrostatic Precipitation 4 Lennox PureAir Air Purification System Photocatalytic Oxidation 5a activTek INDUCT 2000 #1 Ultraviolet light 5b activTek INDUCT 2000 #2 Ultraviolet light 6a Air-Zone Air Duct 2000 #1 Ozone generator 6b Air-Zone Air Duct 2000 #2 Ozone generator 7 APCO Fresh-aire UV / PCO / Carbon 8 HVAC UV 560 Ultraviolet light

Thespecific testingwas oriented toaddressfourmaintopics:1. Ozone emissionratesofelectricallyconnectedin‐ductaircleaners(testingon

allaircleanersinTable2.1)2. Influenceofflowrateonozone emissionrate(mostaircleanersin Table2.1)3. Influenceof temperatureand relativehumidityonozoneemission rate(Air

Cleaners3and5b)4. Repeatabilityoftestingandimpactoforderoftesting(AirCleaners5a and

5b) Toaddresstopic3,thetemperatureandrelativehumidityoftheairwerevariedintheductbyadding steamand/or usinganelectricalheatingelement.Therangeoftemperaturetestedwas25–45 °Candtherangeofrelativehumidity was25‐75 %. Toaddresstopic4,bothunitsof aircleaner5weretested3‐4 timesalternatingbetweendoingthe testingin the orderspecifiedinthestandard(lowtohighflow)andthereverse. This wasdone toexploreanyimpactofairheatingasthefan heatsairinthetestductaswellashysteresisoftheozoneanalyzer(ormoregenerally,thestandarditself). 2.3 Field testing

InTask3and4of In‐duct air cleaning devices: Ozone emission rates and test methodology theobjectivewastodeterminehowmuchtheozoneconcentrationcanrisewithin buildingenvironments whenan electricallyconnectedin‐ductaircleanerisoperating.Thiscanbe accomplishedbymeasuringtheconcentrationinabuilding withthedeviceonwhile accountingforthebackgroundozoneconcentration.However,itisnotpossibletoextrapolatethis singleresulttomakepredictionsforotherhomes,norisitpossible tousetheconcentrationalone tomakecomparisonswithlaboratorymeasurementsofozoneemissionrates. Thisisbecauseeachbuildingremovesozoneatdifferentrates,byairleakageandreactionswithbuilding

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surfaces.Thus,toextrapolateto otherbuildingenvironments andmakecomparisonswithlaboratoryresults,themethoddevelopedforthe field testing isbasedoncollectionofozoneandCO

Documents

In-duct air cleaning devices: ozone emission rates and test ......Contract No. 09-342 In-duct air cleaning devices: Ozone emission rates and test methodology Principal Investigators: