The Absorption and Scattering Characteristics of Interior ...

TheAbsorptionandScatteringCharacteristics

ofInteriorLivingWalls

MahsaAkbarnejad

AThesis

Inthe

BuildingScienceGraduateProgram

PresentedinPartialFulfillmentoftheRequirementsfortheDegreeofMasterofAppliedScienceinBuildingEngineering/BuildingScience

Atthe

BritishColumbiaInstituteofTechnology

Burnaby,BritishColumbia,Canada

BritishColumbiaInstituteoftechnology

Date(January,2017)

3

TableofContents

1.ABSTRACT..........................................................................................................................5

2.INTRODUCTION................................................................................................................6

3.LITERATUREREVIEW.....................................................................................................93.1. Acousticalcharacteristicsandparametersofvegetation....................................103.2. Acousticalcharacteristicsandparametersofsubstratesandporousmaterials.............................................................................................................................................183.3. Materialabsorptionandscattering;effectonroomacoustics...........................223.4. Experimentalmethods.....................................................................................................323.4.1. Absorption..................................................................................................................................323.4.2. Scattering....................................................................................................................................323.4.3. Reverberationtime.................................................................................................................33

3.5. Roomcriteria......................................................................................................................35

4.METHODOLOGY.............................................................................................................364.1. ScopeandHypotheses......................................................................................................364.2. Materials...............................................................................................................................374.2.1. Substrate..........................................................................................................................394.2.2. PlantsDescription........................................................................................................414.2.3. PlantProperties............................................................................................................434.3. Measurementprocedureofplantproperties..........................................................444.3.1. Absorption..................................................................................................................................46Intoaccesstheconsistencyofthemeasurements.........................................................................484.3.2. Scattering....................................................................................................................................504.3.3. ScatteringMeasurements.....................................................................................................51ThescatteringcoefficientofSubstrate(30%pumice,70%pottingsoil).............................51

5.Result................................................................................................................................565.1. Plantproperties(Physicalpropertiesoftheplantsstudied).............................565.2. AbsorptionandScattering..............................................................................................605.2.1. AbsorptionofEmptyRoom:................................................................................................605.2.2. Absorptionoflivingwallsystems:...................................................................................615.2.3. Absorptionevaluationofamultipleofpanels............................................................75

5.3. 1/3ScaleMeasurements;AbsorptionandScattering...........................................78Absorptioncoefficientofdifferentspecies........................................................................................795.3.1. Thescatteringcoefficientofplantspecieschangeswithdifferentpercentagecoverageofvegetation................................................................................................................................86

6.Discussion........................................................................................................................916.1. Absorptionoflivingwallpanelmeasurement........................................................916.1.1. Effectofmoisturecontentandvegetationonthecarries’absorption.............92

6.2. Absorptionandscatteringof1/3scalemodel;thespeciestypeeffectonabsorptionandscatteringcoefficientatdifferentcoveragedensity.............................936.2.1. Scattering....................................................................................................................................986.2.2. Therelationshipbetweentheabsorption&scatteringcoefficientandthepropertiesofsixavailablespecies.......................................................................................................101

6.3. Solvingfortheacousticalcoefficient.......................................................................1036.3.1. Attemptedmethodone.......................................................................................................1046.3.2. Resolvingequation................................................................................................................106

4

6.3.3. ScatteringcoefficientforapplicationinOdeon........................................................1086.4. Roomsensitivityanalysis............................................................................................1106.4.1. Roomdefinition......................................................................................................................1106.4.2. Modeltheroomeffectoflivingwalls............................................................................112

7.CONCLUSIONSANDOUTCOMES..............................................................................117

8.FUTUREWORK.............................................................................................................119

GLOSSARYANDABBREVIATIONS...................................................................................120

AKNOWLEDGEMENTS........................................................................................................122

BIBLIOGRAPHY.....................................................................................................................123

APPENDICES..........................................................................................................................126Appendix1:Theconsideredacousticalstandardsandcriteriainthisresearch....126Appendix2:Irrigationsystem..................................................................................................127Appendix3:1/3scaledturningtableparameters............................................................127Appendix4:Equipmentandfacilities....................................................................................128Appendix5:ThemeasurementconditionofCarrierA&B............................................129Appendix6:.....................................................................................................................................131

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1. ABSTRACT

Installationofinteriorlivingwallsisincreasingrapidlyduetotheirbeauty,biophilic

designandtheirpotentialcontributiontoindoorenvironmentalquality.However,

thereislittleunderstandingofthespecificeffecttheyhaveontheacousticsofa

room.

Toadvancethestateofpractice,thisinterdisciplinarystudyexplorestheacoustical

characteristicsofinteriorlivingwallstodeterminehowtheycanbeusedto

positivelybenefitroomacousticbyreducingexcessnoiseandreverberation.

Specifically,theobjectiveoftheresearchistomeasuretheacousticalcharacteristics

oftheinteriorlivingwallinordertodeterminetheirabsorptioncoefficient,

scatteringcoefficient,andtheparametersthatmostsignificantlyimpactthese

coefficients.

First,aseriesofmeasurementsarecarriedoutinareverberationchamberto

examinerandom-incidenceabsorptionbyconsideringparameterssuchascarrier

type,moisturecontent,vegetationtype,andsubstrate.Inaddition,bothabsorption

andscatteringcoefficientsareexaminedbyconsideringvariousvegetationtypes

andcoverage.Thefindingsfromempiricalmeasurementsfacilitateasensitivity

analysis,withtheuseofthecommercialsoftwareOdeon,oftheabsorptionand

scatteringcoefficients.

Next,theempiricalabsorptionandscatteringcoefficientsareusedonamodel,

developedinthecommercialsoftwareOdeon,toseetheeffectofinteriorliving

wallsonroomacoustics.Theaimofthisstudyistoevaluatetheapplicationof

interiorlivingwallsasasustainableandacousticallybeneficialmaterialfor

buildingsofanykind.

Keywords:acousticalcharacteristicsofinteriorlivingwalls,soundabsorption

coefficient,soundscatteringcoefficient,Odeonsoftware,roomacoustics,livingwall

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2. INTRODUCTION

Noise…isoneofthechiefdrawbackstotheenjoymentofmodernurbanliving.

- Dr.VernO.Knudsen,1967

This quote highlightsthe profound effect ofnoise on the quality of urban life.

Therefore,itisimperativetocomeupwithpracticalacousticalmeasurestoreduce

unwanted noise in living, studying and working environments.This research will

determine if the newtechnologyof living walls can reduce noise andwhetherthe

improvement of room acoustics can be truly considereda benefit of the modern

technology.

Tomeettheacousticalcriteriaforroomsawiderangeofbuildingmaterialsare

availableforuseinsideoftherooms.Usinginteriorgreenwalls,whichaddress

multipleissuesinthesustainabilitydiscussion,maybeanefficientoptionforthe

designteam.Theacousticcharacteristicsmustfirstbequantifiedintermsof

absorptionandscatteringproperties.

Inordertodeterminetheacousticalimpactofusinglivingwallsinaroomandto

makeitpossibletopredicttheireffectinroomdesign(layoutoftheroom),the

absorptionandscatteringcharacteristicofsystemsshouldbeempiricallyevaluated

andtheimpactofthemosteffectivecomponentsoftheinteriorlivingwallsystems

mustbeunderstoodanddefined.

Additionaltothepotentialacousticimpactoflivingwalls,introducingaplanttothe

livingspacebreakstheroughness,thecoldness,anddisciplinaryaestheticnatureof

urbanarchitecture(Figure1).Plantsalsoactasnaturalair-conditioners,removing

carbondioxideandotherpollutantssuchastoxicvolatileorganiccompoundsfrom

theairandreleasingoxygen,andcontributingtoacomfortablerelativehumidityof

45-65percentandtemperatureof20o-22oC[23].

7

Figure1.Interiorlivingwallinstallation[9]

Theinteriorlivingwallsystemiscomposedofthreemajorcomponents:carrier

panel,substrateandplants(leaf,stemandroot).Eachplaysaspecificrolein

absorbingandscatteringsound.Therefore,itisnecessarytocharacterizetheeffect

ofeachcomponentseparatelyaswellasthecombinedeffects.

Thecarriersaremadeinmanyformsfromavarietyofmaterialssuchasstainless

steel,plastic,andpolypropylenefabrics.Thesubstratecanvaryintermsof

percentageoforganicmatter,aggregatetypeandrangeofmoisturecontent.Plants

candifferintermsofphysiology,structureandthedensityofwallcoverage.Interior

livingwallsaresupportedwithanautomatic,closedcircuitirrigationsystem,some

withanin-linefertilizerandsomewithawaterreservoir.Interiorlivingwallsneed

about5to10μmole/m2/soflight,whichcanbeprovidednaturallywithstandard

sizewindowsintheroom.Naturaldaylightisthebestchoicetoprovideinterior

livingwallsystemswithnecessarylightforplantgrowthandleaves.Insituations

wherethatisnotpossible,alightingsystemcanbeinstalled.

Specificobjectivesofthisresearchareprimarilytomeasuretheacoustical

characteristicsoftheinteriorlivingwallinordertodeterminetheirnormaland

diffuseabsorptioncoefficient,scatteringcoefficient,andtheparameter,whichmost

8

significantlyimpactthesecoefficients.Asecondaryobjectiveistousethemeasured

absorptionandscatteringcoefficientdatatomodeltheeffectsoftheinteriorliving

wallsusingthecommercialsoftwareOdeonandinvestigatethemodelssensitivity

tothemeasureddata.

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3. LITERATUREREVIEW

Noise,alsoknownasinvisiblepollutionbyacousticalexperts,hasagreatimpacton

happiness,andthephysicalandmentalhealthofhumanbeings.TheWorldHealth

Organization(WHO)identifiedlow-frequencysoundasaparticularenvironmental

noiseproblem,itsannoyancerisingwithincreasingsoundlevel[1].

Figure2.Interiorlivingwallinstallationincommercialbuildings[10]

Theinfluenceofcontactwithnatureonthehealthandpsychologicalwell-beingof

humansisrepresentedinnumerousliteratures.Anexaminationoftheeffectof

beingclosetogreeneryillustratedarelieffromstress,whichcanhelptoimprove

differentaspectsofwell-being[1].However,limitedresearchoninteriorgreeneryis

available.

Theliteraturesupportingthisthesisfocusesonthreemaintopics:acoustical

characteristicsandparametersofvegetation,acousticalcharacteristicsand

parametersofsubstrates,effectofmaterialabsorptionandscatteringinroom

acoustics.

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3.1.Acousticalcharacteristicsandparametersofvegetation

Previousstudieshaveshownthatleavesofplantsattenuatesoundbyreflecting,

refractingandabsorbingacousticenergyinsmallamounts.Martensevaluated

soundpropagationthroughamodeledforestinananechoicchamber,andfound

thatplantsactasalow-passfilter[19].Healsostudiedacousticreflection

characteristicsofdeciduousplantleaves,andshowedtheimportanceofleaf

dimensionandleafmassforsoundreflection[18].AnotherinvestigationbyMartens

examinedreverberationpatternandsoundenergyabsorptionoffourtypesofplant

leavesinasoundfieldusingaLaser-Doppler-Vibrometersystemoverawide

frequencyrange(0-100Hz)[20].Inanotherinvestigation,hemeasuredsound

reflectionoffaplantleafasafunctionofleafmassusingpulsedandpuretones.The

resultofthisstudyshowedtheimportanceofthedimensionsofaplantleaf,

especiallyathighsoundfrequencies,andthemassoftheleaftissueonthereflection

ofsoundwaves[21].

Attenborough’smeasurementsofleafvibrationinducedbysoundshowedthat

absorptionbyleavesisimportantathighfrequenciesabove1kHz,whereasbelow1

kHzthereislittlesoundabsorptionbyleaves[3].Thiskindofstudywasdonewith

theaimofunderstandingthemechanismsofreflection,diffractionandabsorptionof

soundwavesaroundplantleaves.

InthestudybyAzkorra,twodifferentstandardizedlaboratorytestswereconducted

onthecontributionofverticalgreenerysystemstonoisereduction[21].Findings

indicatedaweightedsoundreductionindex(Rw)of15dBandaweightedsound

absorptioncoefficient(a)of0.40attributedtothemodular-basedsystems.

ComparingAzkorra’sresultswiththoseofpreviousstudies,itcanbeconcludedthat

theintroductionofthegreenwallsintothereverberationroomresultsina

reductioninthereverberationtimefrom4.2to5.9,highlightingandquantifyingthe

soundabsorptioncapacityofthisconstructionsystem[21].

Theleavesofplantsabsorbthevibrationofsoundwaves[23].Acompletestudyon

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theacousticandmechanicalcharacteristicsofplantleavesstillneedstobespecified

foruseininteriorgreenwalls.

VanderHeideninvestigatedthecomplexityoftheplantandsoilinterfaceand

possibleeffectsofvegetationontheacousticalpropertiesofsoilsurfacessuchas

porosityandsoilstructure.Hisresearchindicatedgreatinfluenceofvegetationon

theporosity,inorganicandorganicmattercontent,watercontentandsoil

temperature[26].Theresultsalsoindicatedacorrelationbetweenthepenetration

ofrootsintothesoil,andtheporosityofsoil.

InanexperimentbyAylor,soundattenuationinvegetatedareaswithdifferent

configurationsofplantsandgroundconditionswasexamined.Heconsideredthe

effectofarea,width,thicknessandsurface-areadensityoftheleaves,aswellasstem

diameteranddensityandgroundimpedance.Hedescribedtherelationship

betweenabsorptivecapacityoftheplantmaterialandsoundattenuation[4].Aylor’s

resultsindicatedthatfoliagereducessoundtransmission,especiallyathigh

frequenciesmainlybystems,andmoreefficientlywithincreasingleafdensity,leaf

widthandleafthickness,asshowninFigure3.

Figure3.Excessattenuationvs.plantdensity(Plant/m2)andleafareadensity(m-1)atdifferentfrequencies[4]

Wongexaminedthesoundabsorptioncoefficientofverticalgreenerysystemsinthe

reverberationchambertoshowtheattenuationthroughoutthefrequencyspectrum

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forvaryingLeafAreaIndex(LAI)(Figure4).Figure5illustratedtheaveragesound

absorptioncoefficientrelativetocoverage.However,hisstudydidn’tdefinethe

effectofscatteringcoefficient.Diffractionisaconcernbecauseitsignificantlyaffects

thesoundpressurelevel(SPL)atlowfrequencies[29].Additionally,Wongcarried

outinsertionlossexperimentson8systemsoflivingwallsinHortPark.The

frequency-dependentaverageSPLreadingsandinsertionlossduetothedifferent

plantcharacteristicsineachzoneareshowninFigure6andFigure7.

Figure4.Verticalgreenerysystemwithempty,43%,71%and100%greenerycoveragedensitiesinreverberationchamber(fromlefttoright)[29].

TheresultsofthestudybyPriceshowedthestrongerattenuationininsertionlossat

lowtomiddlefrequenciesthatisduetotheabsorbingeffectofthesubstrate.

Furthermorethesoundabsorptioncoefficientincreasedwithincreasingfrequency

andgreatergreenerycoverage.Itwasshownthatverticalgreenerysystemsare

effectiveinreducingsoundlevelsaswellasabsorbingsoundenergyandfoundthat

scatteringbyleavescancontributetonoiseattenuationespeciallyabove1kHz[17].

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Figure5.Averagesoundabsorptioncoefficientrelativetocoverage[17].

Figure6.AverageSPLreadingsatthebackoftheentireeightverticalgreenerysystemsduringtheacousticsexperimentsinHortPark[17]

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Figure7.Averageinsertionlossfortheentireeightverticalgreenerysystems(VGS)duringtheacousticalexperimentsinHortPark[17]

Yangexaminedrandomincidenceabsorptioncoefficientforsoilwithoutvegetation,

soilwithvegetation,above-groundcomponentsofplantsandgreenwallwithout

vegetation.Healsomeasuredrandomincidencescatteringcoefficientsofabove-

groundcomponentsofplantssuchasleafandstemsinareverberationchamber

[11].Theabsorptionandscatteringcoefficientsofdifferentinstallationsof

vegetationweredeterminedinthereverberationchamberinordertoillustratethe

influenceoffactorssuchassoildepth,soilwatercontent,plantsize,levelof

vegetationcoverageandthelike.

Withincreased soil moisture content,astrong decrease in absorption coefficient

wasreported,sincetheapplicationofwatertosoilresultsinadeclineinporespace.

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Figure8.Absorptioncoefficientof200mmtopsoilwithdifferentsoilmoisturecontent[11]

Aninvestigationoftheeffectofthecombinedsoilsubstrateandlow-growing

vegetationonabsorptioncoefficientshowedbetterabsorptionatlowandmid

frequencies(ratherthanhighfrequenciesabove2000Hz)withincreasing

vegetationdensity.Thislikelyhappensduetoviscousfrictionlossesandtheinertia

effectofvegetationonsoundabsorptionatlowandmidfrequencies[11].

Figure9.Absorptioncoefficientoftopsoilwithdifferentlevelofvegetationcoverage[11]

Lookingseparatelyattheabsorptionandscatteringcoefficientoftheaboveground

components,fordifferenttypesofvegetationsuchasBuxusandIvywithvarious

levelsofvegetationcoverage,showedthatgenerallytheabsorptioncoefficient

increaseswithincreasingvegetationdensityandleafsize.

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Figure10.Absorptioncoefficientofvegetationwithdifferentlevelofvegetationcoverage/density.(a)Buxus,(c)Ivy[11]

InFigure11itcanbeseenthat,justlikeabsorptioncoefficient,thescattering

coefficientincreaseswithincreasinglevelsofvegetationandleafsizeforbothtypes

ofplants.

Figure11.Scatteringcoefficientofvegetationwithdifferentlevelsofvegetationcoverage/density.(a)Buxus,(c)Ivy[11]

Frominvestigationsonagreenwallwithoutvegetation,itwasreportedthatagreen

wallwithhighlyporoussubstratemaintainedahighabsorptioncoefficienteven

withhighmoisturecontentFigure12[11].

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Figure12.Absorptioncoefficientofthegreenwallwithdifferentlevelsofsubstratemoisturecontent[11]

ThereisalsoastudybyHoroshenkovbasedonimpedancetubemeasurements,

whichevaluatedtheinfluenceofleavesontheacousticabsorptionofsoil,plants,

andtheircombination.Theresultshowedthatthepresenceofplantswitha

particulartypeofleafcouldresultinaconsiderableimprovementintheabsorption

coefficientofagreenwallatcertainwatersaturationlevelsincomparisonwiththe

wallwithoutvegetation[25].

InthestudybyAlessandrothenormalincidencesoundabsorptioncoefficientoften

specimensofFernandthreespecimensofBabyTearsweremeasuredinthe

presenceandinabsenceofasubstrate[47].Thesoundabsorptioncoefficientwere

measuredinthefrequencyrangeof50-1600Hzusingaverticallymounted

impedancetubewithadiameterof100mm.Themeasurementswerecarriedoutin

accordancewithUNE-ENISO354-2standards.Thesoilsubstrateusedforthe

measurementsweremadeof70%coconutfibersand30%expandedperlite.The

morphologicalparametersoftheplants,suchasareaofasingleleaf,numberof

leavesinaplant,heightofaplant,predominantangleofleavesorientation,were

alsomeasured.Themeasurementsresultsconfirmedthatplantsareabletoabsorba

considerableamountofacousticenergy,particularlyinpresenceofthesoil

substrate.Thesoilsubstrateisabletoabsorbupto80%ofacousticincidentenergy,

atfrequenciesabove1000Hz[47].

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3.2.Acousticalcharacteristicsandparametersofsubstratesandporousmaterials

Anumberofstudieshavebeendoneonthesubstratepropertiesthathaveaneffect

onacousticalresponse.AstudybyTittmann[24]illustratedtheinfluenceof

saturationonthespeedandattenuationofcompressionalandshearswavesin

porousmaterials.

Attenborough’smodeltookintoconsiderationthephysicalpropertiesofmaterials

toformulateatheoryforsoundpropagationinporousmaterials.Knowinganumber

ofphysicalparameterssuchasflowresistivity,porosity,layerthicknessand

structureshapefactors,theacousticalpropertiesofrigidporousmaterialscanbe

predictedusingAttenborough’stheory[3].

ApreviousstudybyOelze,O’Brien,andDarmodydeterminedtheacoustical

attenuationcoefficientandthespeedofsoundpropagationtobeafunctionofsoil

type(sixsoiltypeswereclassified)anddifferentmoisturecontents.Theresults

illustratedthat,generally,theattenuationcoefficientsincreasewithcompactionand

watercontent[33].

DelanyandBazleydeterminedtheacousticalpropertiesofanumberoffibrous

absorbentmaterialsusingtransmission-lineanalysis.Theiraimwastoprovidethe

expectedvalueoftheflow-resistanceformaterials[8].

Aylor’sstudyonsoilattenuationcharacteristicsshowed(Figure13)bettersound

attenuationatlowfrequenciesforthesofterandmoreporousthesoilsurface[4].

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Figure13.ExcessAttenuationforafinesandyloam(o)andforthesoilafterdisking(Ʌ)vs.frequency[4]

TheresultfromtherecentstudybyVanderHeidenindicatedthatathinsoillayer

providesasignificantabsorptioncoefficient,butincreasingthesoildepthmorethan

90mmdidnotresultinalargechange,Figure14[26].Therefore,itcanbe

understoodthatsoileffectsonabsorptioncoefficientdependmoreon

characteristicssuchasporosityandflowresistanceratherthandepth.

Figure14.Absorptioncoefficientoftopsoilwithdifferentsoildepth[26]

Examiningtheacousticalcharacteristicsofgreenroof,itwasconfirmedbyConnelly

thatthereisarelationshipbetweentheplantcommunityandsoundabsorptionas

wellasbetweensoildepthandabsorption[44].Connellymeasuredtheabsorption

coefficientofvegetatedroofsonarooftopexperimentalset-upforthreeplant

communitieswitharangeofdepthsofsubstrates.Thethreedifferentplant

communitieswereselectedbasedontheiraerialbiomass(foliageabovesubstrate)

20

androotsystemasstructuraldifferencesinexaminingtheabsorptionpotentialof

greenroofs.Theresults,showninFigure15,illustratetheincreaseinabsorption

coefficientofthesubstrate(withoutvegetation)withdepthandfrequency.

Figure15showstheabsorptioncoefficientofthesubstrateontherooftop.

Absorptioncoefficientincreaseswithfrequencyupto1250Hzthenitstaysconstant

athigherfrequenciesupto4000Hz.Italsocanbeinferredthattheabsorption

coefficientincreaseswithdepth[44].

Figure15.Measured third-octave diffuse-field absorption coefficients of reference roof and substrates of 50- to 200-mm depth in rooftop test plots.[44]

Figure16.Measuredthird-octave-banddiffuse-fieldabsorptioncoefficientsofrooftoptestplotsplantedwithsedums(P1).[44]

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Figure17.Measuredthird-octave-banddiffuse-fieldcoefficientsofsubstrateandsedums(P1)inrooftoptestplots.[44]

Figure18.Measured third-octave-band diffuse-field absorption coefficients of 3 plant communities (substratedepths125e200mm)after2seasonsofestablishment[44].

Figure16 and 17 from the same study [44] showedthat with vegetation

(established P1 communityofplanted sedum albumandmoss) the absorption

coefficient trend of increase with soil depth wasthesame asthe substrate only.

Generally speaking plots with community P1 wereless absorptive than the

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substrateplots.Whilethechangesinabsorptionwithfrequencyissimilarforboth

(Figure17).

Figure18showsthataftertwoyearsofestablishment3differentplantcommunities

have similar absorption trends. However, the range of absorptivity between three

communitiesoverlappedatsomefrequencies.

ThestudybyConnellyshowedthat:theabsorptivityofvegetatedroof(livingroof)is

a function ofsubstrate depth, establishment of plant community and moisture

contentofsubstrate[34].

Furtherresearchontherelationshipofplantrootstructuretoporosityand

substratemass,asthevegetationestablishesovertime,isrequiredinorderto

measureandfullyunderstandtheimpactofplantestablishmentontheeffective

absorptionofthevegetatedroofandwallmateriallayer,substrateandestablished

plantcommunities.

Therehasbeenlittleworkcompletedonsimilareffectsassociatedwithsoildepth,

moistureandplanttypeinlivingwalls.However,wecantakesomeguidancefrom

researchongreenroofs.

3.3.Materialabsorptionandscattering;effectonroomacousticsAllsurfacesoftheroomabsorbandreflectsoundenergy.Absorptionremoves

soundenergyfromaroom.Therefore,manyfactorssuchasceilingheight,room

volume,surfacetypesofallmaterialsandanyequipmentinaroomhaveadirect

impactontheroom’stotalsoundlevelandsoundabsorption.Materialshavesound

absorptionandscatteringpropertiesthatcanbequantifiedwithfrequency-

dependentsoundabsorptionandscatteringcoefficients.

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Acousticalabsorptionresultsfromfrictionandresonancephenomena.Absorption

throughfrictionispossiblewhenusingporousandfibrousmaterials,workingbest

inthemidandhighfrequencies.Iftheabove-mentionedmaterialtypesareof

adequatethicknessorbackedbyair,theycanbeefficientinlowfrequenciesaswell.

Resonantabsorbersareefficientatlowfrequencies[31].

NeubauerandKostekreviewedandcomparedseveraldifferentreverberation

modelsandtheirderivations,beyondSabine(Equation1),includeErying(Equation

2),Millington-Sette(Equation3),Fitzroy(Equation4)andFitzroy-Kuttruff

(Equation5)[22].InFigure19,itcanbeobservedthatthevaluescalculatedusing

TohyamaandEyring’smodeldifferconsiderablywiththeresultfromtheother

formulae.ItcanbeseenthatTohyama,Fitzroy,ArautendstooverpredicttheRT.It

alsoshowedthatthenewformulamentionedinthepapermatcheswellwiththe

measuredreverberationtime(RT).

Sabine’sformula

T60=0.161V/A Equation1

Eyring’sformula

T60=(0.161V)/(-Sln(1-α)) Equation2

S - total surface area (m²) . α - average absorption coefficient.

Millington-Sette’s

formula

T60=(0.161V)/(Σ(-Si.ln(1-αi)) Equation3

Si - surface area of the material αi - its actual absorption coefficient.

Fitzroy’sformula

T60=0.16V/S2[(-x/In(1-αx))+(-y/In(1-αy))+(-z/In(1-αz))]

Equation4

x, y, z - total areas of two opposite parallel walls in m2,

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αx, αy, αz - average absorption coefficients of a pair of opposite walls, S - total surface area of the room in [m

2],

V - total volume of the room [m3].

Fitzroy-Kuttruff’sformula

T60=(0.32V/S2)(h(1+w)/α*L.w/α*cf) Equation5

V, S - volume in [m

3] and total surface area of the room in [m

2],

h, w, l - room dimensions: height, width and length in [m], α*Lw, α

*cf- average effective absorption exponent of walls, ceiling

and floor.

Figure19.Comparisonofmeasuredandpredictedreverberationtimevaluesforaroomwithavolumerangeof50-200

MeasurementsbyDucourneau&Planeaushowedthatthechangeinaverage

acousticalabsorptiondependsontherelativedistancebetweenthesoundsource

andtheabsorbentpanels[14].

Thecurrentlyusedformulastocalculatethereverberationradiushavebeenderived

bytheclassictheoriesofSabineorEyring.However,thesetheoriesareonlyvalidin

perfectlydiffusedsoundfields;thus,onlywhentheenergydensityisconstant

throughoutaroom.Nevertheless,thegenerallyusedformulasforthereverberation

radiushavebeenusedinanycircumstance,regardlessoftheuniformityofthe

-0,5

0

0,5

1

1,5

2

2,5

3

3,5

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Room volume in m3

Reverberation Time [s]

Difference between measured RT and Sabine's

approxim. T60 [s] Sabine's approxim. [s]

Measured Value (RT) [s]

Difference: Measured RT minusSabine's approxim. [s]

Fig. 7. Differences between "approximated" and measured reverberation time

Comparison of Measured and Calculated RT

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 50 100 150 200

Room volume in m³

Reverberation Time in s

Measured RT Eyring New Formula

Eyring-Kuttruff Fitzroy Mi l l i n g to n -Se tte

Tohyam a Ara u An n e x D o f p rEN 1 2 3 5 4 -6

Fig. 8. Comparison of measured and predicted reverberation time values for a room with a

volume range of from 50 to 200 m³

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distributionofabsorption.Arau-PuchadesandBerardihaswritten

theexpressionofthereverberationtimeas:

T=(0.16V/Ax)Sx/S.(0.16V/Ay)Sy/S.(0.16V/Az)Sz/SEquation6

TheArau-Puchades’sformulashowsthatFitzroy’stheorywasnotcompletely

correct,asitwasonlyvalidwhenthereverberationtimesineachdirection(Tx,Ty,

Tz)areequal,orapproximatelyequal.Atendencyforco-incidenceoftheFitzroy’s

formulawiththeSabine’sandEyring’sformulasmayoccurdependingonthe

closenessoftheaverageabsorptioncoefficientsineverydirection.However,

wheneverthereverberationtimesarewelldifferentiatedamongthedirections,then

theFitzroy’sformuladivergessignificantlyfromtheoreticalresultsasrecently

showninsomeroundrobintests(Mehta,Mulholland,1976;Istafa,Bradley,2000;

Ducourneau,Planeau,2003).ThenewformulaEquation6coversdiffuseandnon-

diffusesoundfields,andappearsasageneralformulationofthetheoryof

reverberation[46].

AccordingtothedatafromCavanaugh,itcanbeconcludedthatwell–placed,correct

amountsofabsorptivematerialsintheroomcancontrolthereverberation

characteristicsoftheroom[31].ThestudybyBistafaandBradlyvalidatesthis

findingthroughchangingthelocationandamountofabsorptivematerialsina

classroom[5].Theyalsodeterminedthatspreadingtheabsorptivematerialsaround

theroomsurfacesismoreeffectiveincontrollingreverberationratherthanputting

theminonearea.Thisworkwasfollowedupwithfurtherstudythatnotedand

rankedabsorptionsurfacedesignvariationsandtheirimpactonproducingadiffuse

soundfield[5].Thesefindingsareveryrelevanttothepotentialeffectsoftheliving

wallinthat,livingwallsaretypicallyinstalledonalimitedwallareainaroom

Acousticalscatteringresultsfromtheroughnessofthematerial,knownasdiffusing

anddiffractionduetoedgeandalimitedsurfacesize.Scatteringdoesnotremove

thesoundenergyfromaroombutreducesspecularreflection.Scatteringfrom

26

diffusionisnotwellunderstood.Scatteringfromdiffractionisalsonotfully

understoodbutisknowntobedependentonincidencepathlengthsandangleof

incidence.VorlanderandMommertzintroducedthescatteringcoefficientand

defineditas:thetotalreflectedenergyminusSpecularreflectedenergy[27].

VorlanderandMommert’sresearchonscatteringhasprovidedthemethodologyby

whichtodefineandmeasurethescatteringcoefficientforvariousmaterials.They

comparedthescatteringcoefficientofrandomincidencefromthemeasurementof

impulseresponsesfromafree-fieldmethodandareverberationchambermethod

forvariousorientationsonasamplesurface.Theresearchidentifiedthe

reverberationchambermethodtobemoreconsistentformeasuringthescattering

ofreflectivesurfaces[27].

Sauro&Michael’sresearchconfirmedthatalltheenergyfromanincidentsound

waveisreflectedasspecularlyreflectedandscatteredenergy.Inaddition,the

amountofscatteredandspecularenergydependsonthewavelengthsofthe

incidentenergy[40].

ThestudybyChristensenandRindelinvestigatedthescatteringofreflectedsound,

sd(bydiffraction,duetosurfacedimensions,angleofincidence,incidentand

reflectedpath-lengths),andsurfacescattering,ss(roughnessofsurfacematerial)

[6].Adecreasedsensitivityofroomstothescatteringcoefficientofmaterialsisdue

toincreasedsoundfielddiffusivity.

Mostnumericalmodelslookatabsorptionintermsofspecularreflectiononlyand

ignorescattering.

Odeonsoftwarewasdevelopedforsimulatingtheinterioracousticsofbuildings,

usingimage-sourcemethodcombinedwithraytracing.Givenasetofgeometryand

surfacepropertiesandabsorptionandscatteringcoefficients,theacousticscanbe

predicted,illustratedandanalyzed.InOdeonsurfacediffractionanddiffused

diffractionarecombinedtoestimatethereflection-basedscattering.Thescattering

coefficientisdefinedastheamountofscatteredsoundenergyindifferentdirections

overthetotalreflectedsoundenergy,Figure20.

28

materialsandaloweraverageabsorptioncoefficient.Inroomswithnon-mirrored

reflectivesurfaces,theareaofabsorptionisthedeterminingfactorinitssensitivity

toscatteringcoefficients.Sensitivityincreasesastheaverageabsorptioncoefficient

isdecreased.

HuberandBednar[35]studiedtheeffectofthescatteringcoefficientonthe

reverberationtimethroughsimulationresultsfromcomputermodels(CATT-

Acousticv8.0f).First,theyfoundthatCATTwasingoodagreementwiththe

reverberationtimecalculationsaccordingtoSabineandEyring’salgorithmswith

respecttoabsorptioncoefficientonly.Theresultsoftheirstudyillustratedthatthe

lowscatteringcoefficientsproducehighreverberationtimesinthesimulation.

Reverberationtimeisincreasedwhentheabsorptioncoefficientisnotuniform.

Fromtheirresults,italsocanbeunderstoodthattheinfluenceofthescattering

coefficientonthereverberationtimeincreaseswithlargerdifferencesbetweenthe

absorptioncoefficientofthedifferentsurfacesoftheroomanddecreaseswith

increasingtheaverageabsorptioncoefficientoftheroom.Thisstudyillustratedand

summarizedthesignificantinfluenceofthescatteringcoefficientonthe

reverberationtime.

Navarro,etal[38]evaluatedthepredictedvaluesforreverberationtime,absorption

andscatteringcoefficients,fromageometricalacousticmodelandthediffusion

equationmodel.Theywereabletoestablisharangeinwhichthepredictedvalues,

forabsorptionandscattering,fromthementionedmodelsareingoodagreement.

Comparingtheresults,itwasdeterminedthatthevaluesfromthediffusionequation

modelareclosertothevaluesoftheRay-tracingsoftwareforhomogeneousrooms

withascatteringrangegreaterthan0.6andanabsorptionoflessthan0.45.

Therefore,itcanbeusedtopredictreverberationtimeinthatrange.Thesimulation

resultsalsoshowedagreaterimpactofscatteringonreverberationtimeforsmaller

valuesofabsorption.

29

Farinacompletedaseriesofexperimentalmeasurementsofthescattering

coefficientbasedonthewavefieldsynthesismethod[37].Thecomparisonofthe

resultsfromherworkwasingoodagreementwiththenumericalsimulations.Her

workdescribedtheextensionofanumericalsimulation,whichbecomespossibleby

developmenttothepyramid-tracingalgorithm.Hertechniquemakesitpossibleto

derivethevaluesofthescatteringcoefficient.Thescatteringcoefficientwas

introducedasanewconceptinISO17497-1,standard(2013)[12].Whichisan

internationalstandardformeasurementoftherandom-incidencescattering

coefficientinareverberationroomandwillbereviewedinsection3.4.

Tomeasurenormal-incidencecoefficients,absorptionandscattering,Tetsuya,

HyojinandKashiwanohadevelopedanalternativetoFarina’smethod.However,itis

notsufficientlydevelopedyetforthisresearch.Also,theydevelopedanumerical

simulationtodeterminetheabsorptioncoefficientandscatteringbuthaveonly

appliedittosimplesurfacesratherthanthecomplexsurfacessuchasplants[36].

Shtrepi,etalresearchinvestigatedtheeffectofscatteringonsixacoustical

parametersoftheroom,reverberationtime(T30),clarity(C80),strength(G),Early

DecayTime(EDT),definition(D50)andLateralenergyFraction(LF)usingCatt-

acousticsoftware.Sixdifferentscatteringvaluess=10,30,50,60,70,&90%was

appliedtoroomsurfaces(ceiling,sideandrearwalls)toconsiderscattering

variationinthemeasurement.Fromtheresultsitcanbeillustratedthatthedistance

betweensourceandreceivergreatlyaffecttheacousticalparameters.Fromthe

findingsitcanbeunderstoodthatbyincreasingthescatteringcoefficientvalueT30,

C80,GandD50valuesaredecreasing.ItwasalsofoundthatLFandEDTarenot

affectedbyscattering[39].

ApreliminaryevaluationwasdonelastyearatBCITinclassroom317(NE1

building)asshowninFigure18,withdifferentconfigurationsofnewlyplanted

livingwallsinstalled.Areductioninlowfrequencyreverberationwasobserved

30

accordingtothestudyresultsFigure22.Absorptionandscatteringcoefficientwere

notknownandmodellingwasnotvalidated[30].

SoundLevelMeter Microphone Speaker

Amplifier

LivingWallPosion1–WallinCorner

LivingWallPosion2–WallsParallel

LivingWallPosion3–WallsOpposing

Ourresearchisfocusedonquanfyingthesoundabsorbingabiliesofliving

wallsbymeasuringthereduconinreverberaon me.

BenefitsofLivingWalls

Studieshaveshownthatlivingwallsininteriorapplica

onscanoersignificantbenefitstotheoccupants,in

cluding:

Improvedairquality

Reduconsinover300VOCs(1)

Reducedbloodpressure

Reducedlevelsofstressandanxiety(2)

Increasedproducvity(3)

Reducedabsenteeism(4)

Visualaesthecs

ClassroomAcouscs

Pooracouscalenvironmentsnegavelyimpactlearningbyreducingspeech

intelligibility.(5)

Reverb me–ameasureofhowlongittakesforsoundstodecay–isimpacted

bythesoundabsorponoftheroom.

Whatifalivingwallcouldbeusedinclassroomstoabsorbsoundandfoster

learning,andatthesamemeintroduceallofitshealthbenefits?

ContactInformaon

JesseListoen [email protected] 6047910842

AshkonMohammadi [email protected] 6049164701

SoundTesngResults

MaureenConnelly,DirectorofBCITCenterforArchitecturalEcology|RonKrpan,BCITInstructor

LivingWallassembly

ByAshkonMohammadiandJesseListoen

Conclusions

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)

AverageClassroomReverberationTime

WithoutLivingWall

WithLivingWall

EmptyRoom

Speakerin2dierentcorners

Microphoneat5dierentlocaons

5microphonereadingsateachlocaon

50readingsaveragedtofindRT

LivingWallPresent

Wallsin3dierentposions



5Microphonereadingsateachlocaon

150readingsaveragedtofindRT.

TestStandard

ThetesngmethodwasbasedonASTMC42307a(6)

Thetesngwascarriedoutthroughfieldtesng,whichinvolvedphysicallytak

ingmeasurementsintheroom,bothwithandwithoutthelivingwall.Amicro

phonewasusedtorecordrandomnoisegeneratedbyaspeakerandamplifi

er.Thespeakerwasturnedontheno whileamicrophonemeasuredhow

longittookthesoundtodecayby60dB.

TestMethod

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)

WallsOpposingReverbTime

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)

WallsParallelReverbTime

WithoutLivingWall

WithLivingWall

WithoutLivingWall

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)

WallsinCornerReverbTime

WithoutLivingWall

WithLivingWall

WithLivingWall

Introducon—Whyalivingwall?

Posion1WallsinCorner Posion2WallsParallel Posion3WallsOpposing

(1)Knowles,L.,MacLean,P. ,Rosato,M.,Stanley,C.,Volpe,S.,&Yousif,D.(2002).LivingWall:FeasibilityStudyofSLCUniversityofWaterloo.UniversityofWaterloo.

(2)Heerwagen,J.(1990).Thepsychologicalaspectsofwindowsandwindowdesign.Proceedingsof21stannualconferenceoftheEnvironmentalDesignResearchAssociaon,269280.

(3)Marchanct,B.(1982).Alookattheindustrydimensionsandprospects.AmericanNurseryman156,3049.

(4)Conklin,E.(1978).Interiorlandscapingandarboriculture.JournalofArboriculture4,7379.

(5)Zannin,P.H.T,Marcon,C.R.(2007).Objecveandsubjecveevaluaonsoftheacousccomfortinclassrooms.AppliedErgonomics38,675680.

(6)ASTMInternaonal.(2007).ASTMStandardC42307a"StandardTestMethodforSoundAbsorponandSoundAbsorponCoe cientsbytheReverberaonRoomMethod.WestConshohocken,PA.

(7)BuildingBullen93(2003).UnitedKingdom.

Acknowledgments

References

Temperature: 22C

RelaveHumidity: 36%

DewPoint: 7C

AverageReverberaonTime(s)

Frequency(Hz) 125 250 500 1000 2000 4000

WithoutLivingWall 1.07 1.95 0.96 0.45 0.47 0.48

WithLivingWall 1.06 1.25 0.75 0.43 0.34 0.34

PercentReducon 1% 36% 22% 4% 27% 29%

Thelivingwallreducedreverberaon meacrossallfrequencies,comparedtotheroomwithoutaliving

wall.

19%reduconinRTatlowrangefrequencies(125250Hz)

13%reduconinRTatmidrangefrequencies(5001000Hz)

28%reduconinRTathighrangefrequencies(20004000Hz)

BB93recommendsatmaximummidfrequencyreverbmeinclassroomsof0.6to0.8seconds(7).Without

thelivingwall,theroomhadareverbmeof0.64s.Withtheintroduconofalivingwall,theRTdropped

to0.51s,represenngareduconof20%.

Basedonourresearch,itmaybesuitabletointroducealivingwallintoclassroomstoimprovetheacousc

environmentthroughareduconreverberaon me,inaddiontointroducingitsaforemenonedenviron

mentalbenefits.Furthertesngneedstobedoneondierentlivingwallstructuresandclassroomsizesto

getabroadersenseofthesoundabsorbingabiliesoflivingwalls.


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 1.27 1.09 0.86 0.44 0.33 0.30

%Reducon +19% 44% 10% 2% 30% 38%

Room317Info

FloorArea:58m2

WallHeight:2.7m

RoomVolume:160m3


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.96 1.50 0.73 0.39 0.33 0.33

%Reducon 10% 23% 24% 13% 30% 31%


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.94 1.15 0.67 0.46 0.35 0.39

%Reducon 12% 41% 30% +2% 26% 19%

Temperature: 22C

RelaveHumidity: 39%

DewPoint: 7C

Temperature: 22C

RelaveHumidity: 37%

DewPoint: 7C

Materials&SurfaceAreaTotalSurfaceArea:203m2

AcouscCeilingTile:46m2

CarpetFlooring:58m2

Drywall:56m2

LighngFixtures:12m2

LivingWall:3.6m2

WallVegetaon LivingWall

Figure21.PuttingILWindifferentconfigurationintheclassroom[30]

31

Walls in corner

Walls parallel

Walls opposing

Figure22.Reverberationtimeoftheroomwithdifferentconfigurationoflivingwalls[30]


Amplifier









cluding:

Improvedairquality






Visualaesthecs

ClassroomAcouscs


intelligibility.(5)





ContactInformaon



SoundTesngResults


LivingWallassembly


Conclusions

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

EmptyRoom





LivingWallPresent






TestStandard







TestMethod

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

WithoutLivingWall

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

WithLivingWall










Acknowledgments

References

Temperature: 22C

RelaveHumidity: 36%

DewPoint: 7C


Frequency(Hz) 125 250 500 1000 2000 4000


WithLivingWall 1.06 1.25 0.75 0.43 0.34 0.34

PercentReducon 1% 36% 22% 4% 27% 29%


wall.












Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 1.27 1.09 0.86 0.44 0.33 0.30

%Reducon +19% 44% 10% 2% 30% 38%

Room317Info

FloorArea:58m2

WallHeight:2.7m

RoomVolume:160m3


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.96 1.50 0.73 0.39 0.33 0.33

%Reducon 10% 23% 24% 13% 30% 31%


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.94 1.15 0.67 0.46 0.35 0.39

%Reducon 12% 41% 30% +2% 26% 19%

Temperature: 22C

RelaveHumidity: 39%

DewPoint: 7C

Temperature: 22C

RelaveHumidity: 37%

DewPoint: 7C



CarpetFlooring:58m2

Drywall:56m2

LighngFixtures:12m2

LivingWall:3.6m2



Amplifier









cluding:

Improvedairquality






Visualaesthecs

ClassroomAcouscs


intelligibility.(5)





ContactInformaon



SoundTesngResults


LivingWallassembly


Conclusions

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

EmptyRoom





LivingWallPresent






TestStandard







TestMethod

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

WithoutLivingWall

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

WithLivingWall










Acknowledgments

References

Temperature: 22C

RelaveHumidity: 36%

DewPoint: 7C


Frequency(Hz) 125 250 500 1000 2000 4000


WithLivingWall 1.06 1.25 0.75 0.43 0.34 0.34

PercentReducon 1% 36% 22% 4% 27% 29%


wall.












Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 1.27 1.09 0.86 0.44 0.33 0.30

%Reducon +19% 44% 10% 2% 30% 38%

Room317Info

FloorArea:58m2

WallHeight:2.7m

RoomVolume:160m3


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.96 1.50 0.73 0.39 0.33 0.33

%Reducon 10% 23% 24% 13% 30% 31%


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.94 1.15 0.67 0.46 0.35 0.39

%Reducon 12% 41% 30% +2% 26% 19%

Temperature: 22C

RelaveHumidity: 39%

DewPoint: 7C

Temperature: 22C

RelaveHumidity: 37%

DewPoint: 7C



CarpetFlooring:58m2

Drywall:56m2

LighngFixtures:12m2

LivingWall:3.6m2



Amplifier









cluding:

Improvedairquality






Visualaesthecs

ClassroomAcouscs


intelligibility.(5)





ContactInformaon



SoundTesngResults


LivingWallassembly


Conclusions

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

EmptyRoom





LivingWallPresent






TestStandard







TestMethod

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

WithoutLivingWall

0.00

0.50

1.00

1.50

2.00

125 250 500 1000 2000 4000

RT(s)

Frequency(Hz)


WithoutLivingWall

WithLivingWall

WithLivingWall










Acknowledgments

References

Temperature: 22C

RelaveHumidity: 36%

DewPoint: 7C


Frequency(Hz) 125 250 500 1000 2000 4000


WithLivingWall 1.06 1.25 0.75 0.43 0.34 0.34

PercentReducon 1% 36% 22% 4% 27% 29%


wall.












Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 1.27 1.09 0.86 0.44 0.33 0.30

%Reducon +19% 44% 10% 2% 30% 38%

Room317Info

FloorArea:58m2

WallHeight:2.7m

RoomVolume:160m3


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.96 1.50 0.73 0.39 0.33 0.33

%Reducon 10% 23% 24% 13% 30% 31%


Frequency(Hz) 125 250 500 1000 2000 4000

WithoutWall 1.07 1.95 0.96 0.45 0.47 0.48

WithWall 0.94 1.15 0.67 0.46 0.35 0.39

%Reducon 12% 41% 30% +2% 26% 19%

Temperature: 22C

RelaveHumidity: 39%

DewPoint: 7C

Temperature: 22C

RelaveHumidity: 37%

DewPoint: 7C



CarpetFlooring:58m2

Drywall:56m2

LighngFixtures:12m2

LivingWall:3.6m2


32

3.4.Experimentalmethods

3.4.1. Absorption

Anumberofmethodsusedinpreviousstudiesrelevanttothisresearchcanbe

mentioned:random-incidenceabsorptioncoefficientaccordingtoISO354[13]and

random-incidencescatteringcoefficientbasedonISO17497-1[12].VanderHeijden

measuredfreefieldsoundpressurelevelandfoundabsorptionbasedonimpedance

tubemethods[26].MartensusedLaser-Doppler-Vibrometersystemformeasuring

thevibrationvelocityofsmallareasontheplantsoverawidefrequencyrange(0-

100Hz)[20].Wongdeterminedanabsorptioncoefficientthroughinsertionloss

experimentsinareverberationchamber[29].

3.4.2.ScatteringRonaldandMichaelprovidesuggestionstomodifyrequirementsandmethod

recommendationsbyISO-17497-1standardinordertogathermoreaccuratedata.

Theirmeasurementsonhundredsoffullsizedmaterialsamplesillustratedthatthe

shapeandsizeofthesamplesareimportantincollectingthedata.Itis

recommendedthatthestructuraldepthofthesampleformeasurementsshouldbe

lessthan1/16ofthetotalsamplediameter.Andthediameterofthesampleshould

belongerthan3.5meter(137.8inches)atfullscaleinordertogetthemore

accuratemeasurementsatlowfrequencies.Thechamberdoorshouldbeclosedfor

15minutesbeforestartingthemeasurementstoletairmovementinthechamber

stabilize.Duringthemeasurementforeachset,thetemperaturecannotchange

morethantwodegreesCelsius,alsotherelativehumidityofthechambermustbe

constantandabove50%.Theselectedstimulusshouldhavelesssensitivityto

temperature,humidityandairmovementsuchaspinknoise.Thetestsampleson

theturntableshouldbeconstantlyrotatedmorethan3completeturns.Becauseof

therequirementsofthesimulationprogramsthefrequencyrangeshouldbe

extendedfrom100Hzto10kHz[40].

33

Choi,etalusedascalemodeltoinvestigateissuesandambiguitiesofrandom-

incidencescatteringcoefficientmeasurementbasedonISO1749-1[41].They

consideredthreeparameters:theairgapbelowtheturntable,thediameterofthe

turntableandtestsampleabsorption.Theresultsfromtheirworkshowedthat

diameteroftheturntablehasaneffectonthescatteringcoefficientvaluesofthe

baseplateatthehighfrequencybandsbetween1kHzand5kHz.Increasingtheair

gapundertheturntableto50mmleadsinahigherscatteringcoefficientofthebase

plate.Also,changingtheabsorptionofthetestsampledidnotchangethescattering

coefficientsignificantly.

3.4.3. Reverberationtime

TheliteraturebyJambrosic,etalreviewsthreedifferentmethodsofreverberation

timeempiricalmeasurementinthefield[32].Themethodsare:theinterrupted

noisemethod,theintegratedimpulseresponsemethodandtheburstmethod.

BalloonswereusedintheburstmethodevaluationandanOmni-directionalsound

sourcewasusedforthetwootherexperiments.Thedifferentmethodswereusedto

measuretworooms.Thefirstroomisa230m3rectangularroom,containinga

numberofacousticmaterials,andthesecondroomisan800m3L-shapehallway

withhardandreflectivesurfaces.Thereverberationtimemeasurementsforthefirst

roomweremoreconsistentcomparedwiththesecondroom.Figure23and24

illustrateabetteragreementatfrequenciesabove125Hzintherectangularroom

andabove1000HzintheL-shapedroom.Fromthisresult,itcanbeconcludedthat

allthementionedmethodsformeasuringreverberationtimeareusableinthe

experimentaslongasthereispowerfulexcitationtoprovidesufficientdynamic

range.Limitedmeasurementshavebeencarriedoutonverticalgreenerysystems,

suchas,thestudybyWong[29].Thesefindingswillsupportthemethodof

evaluationoflivingwalls.

34

Figure23.Room1atposition1[32]

Figure24.Room2atposition1[32]

Toinvestigatetheacousticalbenefitsofinteriorlivingwallssystematically,more

detailsaboutthesoilsurface,thefoliage,diffusionandabsorptioncharacteristics

areneeded.

35

3.5.RoomcriteriaTherearecommonlyadoptedcriteriaforbackgroundnoiselevel,speech

intelligibilityindexandreverberationtimeindifferentinteriorspaces.ASHRAEhas

manycriteriaforallusesandoccupancies.

ASHRAE,LEED(LeadershipinEngineeringandEnvironmentalDesign)andANSI

S12.60areguidelinesforappropriateacousticsinschoolareas.Thesestandards

takeintoconsiderationthebackgroundnoise,speechintelligibility,and

reverberationtime(whichhasaneffectontheothercriteria).Backgroundnoise

level(BNL)canbeidentifiedbynoisecriteria(NC)curves.AccordingtoLEED(LEED

forschool-2009IEQc9)theminimumacousticalperformancerecommendedbythe

criteriaintheclassroomisNC30-40forspacesbiggerthan20,000SF,ASHRAE1

recommendsNC-30.Reverberationtimeshouldbelessthan1.5secondsandNRC

(NoiseReductionCoefficient)rateof0.7inordertomeettheLEEDrequirementorit

shouldhaveT60between0.6to0.7onthebasisoftheANSIstandardS12.60-2012

(Part1).

Appropriate,strategically-placedmaterialsandroomgeometryeffectreverberation

time,andaquietHVACsystemcandecreasethebackgroundnoiselevel.According

tothestudybyKang,appropriateabsorptivecharacteristicsoftheroomsurfaces

canimprovespeechintelligibilityintheroom.Ininternalspaceswithacoustic

defectssuchasechoesandlongreverberation,selectingsuitablescattering

propertiesofboundariesisalsoimportanttoimprovespeechintelligibility[15].For

highspeechintelligibility,SIImustbehigherthan0.75,whileforhighspeech

privacy,itmustbelessthan0.2.Theconsideredacousticalstandardsandcriteriain

thisresearcharelistedinappendixA.

1ASHRAEHandbook,Chapter47,Controlbackgroundnoiselevelsincorelearningspace

36

4. METHODOLOGY

4.1. ScopeandHypothesesThescopeofthisinterdisciplinaryresearchisfocusedontheabsorptionand

scatteringcharacteristicsoflivingwalls.Theempiricaldatacollectionincludesfull

scaleabsorptionmeasurementsoftheconstituentparts-carrier,substrateand

plantsforthreeavailablelivingwallsystems,fullscaleabsorptionmeasureoffully

establishedlivingwallsystems.Plantswereevaluatedovertimetoestablishthe1/3

scaledspecies,1/3-scaleabsorptionandscatteringmeasurementofsixdifferent

plantspecies.

Fromthefindingsoftheliteraturereview,itisexpectedthatthesubstrateisthe

mostsignificantcomponentoflivingwallsintermsofabsorption,andplantsarethe

mostsignificantintermsofscattering.Additionally,thesoundscatteringofliving

wallssignificantlyimpactsthereverberationtimeandcannotbeneglectedin

modelling.Theplantcoveragedensityisalsoimportantintermsofabsorptionand

scattering,whilethecarriertypewillnotbesignificant.Theinteriorlivingwalland

itslocation,asasoundabsorptiveandsoundscatteringmaterial,giventhetypical

sizeofinteriorlivingwallswillhaveaneffectonreverberationtimeinrooms.

Parametersofsubstratemixture,moisturecontent,andoverallplantcoverage

investigated.Thenthesoundabsorptionandscatteringcoefficientsfromthe

reverberantchamberwillbeusedtoinvestigatethesensitivityofroommodellingto

themeasureddata.

37

4.2. MaterialsThepurposeofhavingthreesignificantlydifferentlivingwallsystemsistoseethe

effectsoforganicattributeslikesubstrateandplantsontheabsorptionand

scatteringofabroadrepresentationalrangeofmarket-establishedlivingwall

systems.Ofthethreesystems,twosystemshavesoil-basedsubstrates,whilethe

thirdsystemhasafibrouswool-basedsubstrate.

Figure25.interiorlivingwallsystemdimension.(CarrierTypeA)

Depth= 15.6 cm

Figure26.interiorlivingwallsystem.(CarrierTypeB)

ByNature - Showroom: Studio 490 - 1000 Parker Street - Vancouver, BC, V6A 2H2.

www.bynaturedesign.ca - 1-800-436-2919

The Modulogreen Living Wall

Origin: France

Launch: 2003

Track record: More 500,000 square feet installed all over the world

Canada: A dozen living wall installations in Canada since 2013

A living ecosystem on your wall - how cool is that? Designed with simplicity in mind, and based on living

wall technology popular in Europe, our ModuloGreen Living Wall system ensures your vertical garden

will thrive.

1 - Specifications

The ModuloGreen is a soil-based living wall system, making water use and the maintenance needs

extremely low, thus limiting the long-term cost associated with the system. The horizontal orientation of

the planting areas makes it very easy to plant, and the ample space available for the roots to develop

allows for a diversity of plants to flourish. The smart design also makes it easy to change the plants

according to the season or to customer preferences.

100% recyclable ABS plastic was chosen for its resistance to warping, compatibility with roots and for its

thermal properties. Each module is designed to overlap with another, making the entire living wall

seamless and completely waterproof. 60.00

60.00

10.00

15.00

38

Depth: 15.6 cm

Figure27.interiorlivingwallsystem.(CarrierTypeC)

System1-CarrierAFigure25:Thisisasoil-basedlivingwallsystemwithrelatively

lowwaterconsumption(about220Lperyear/perm2).Thecarrieris100%-

recyclableABSplastic.Theself-regulating,low-outputdripirrigationnetwork

providesfortheplants’waterneeds.Wateroverflowisdraineddirectlythroughthe

bottomedgeofthemodule.Thedesignofthecarriersmakesiteasytoplantandthe

systemprovidesplentyofspaceforrootdevelopment,theformofthecarrierholds

thesubstrateandrootssecurelyinside.

System2-CarrierBFigure26:Thissystemisasoil-basedlivingwallsystemwith

relativelylowwaterconsumption(about220Lperyear/perm2)andusesaself-

regulating,low-outputsoakhosewhichprovidestheplants’water(Thepanelsare

plantedhorizontally,andthesoilisexposed).Thecarrierismadeofstainless-steel,

andcanbeusedforbothinteriorandexteriorpurposes.Theformofthecarrier

presentsthesubstrateastheverticalexposedfacecannotholdthesubstrateuntil

aftertheestablishmentoftheplantroots(30-60daysafterplantinginahorizontal

orientation).

System3-CarrierC

Figure27:Isahybridhydroponiclivingwallsystem.Constantirrigationisrequired

toprovidesufficientmoisturecontentandnutrientsforsuccessfulgrowthofplants

60.00

51.00

10.00

8.50

40

Table1.Weightofthecarriers,carrierswith2differentsubstratemixtureandplantedcarriers

Systems

No. CTA(weight)

CTB(weight) CTC(weight)

1 EmptyCarrier 6.04kg 10.92kg 2.65kg2 Carrierwithsubstrate

(80%soil-20%pumice)25.88kg 32.70kg -

3 Carrierwithsubstrate(70%soil-30%pumice)

26.80kg 34.11kg -

4 Carrierwithpottingsoilonly

- - 3.35kg

5 Carrierwithsubstrateinfieldcapacity(70%soil-30%pumice)

27.30kg 35.00kg 3.79kg

6 Plantedcarrier,(70%soil-30%pumice)(Mixvegetation)*

Mix1=30.20Mix2=32.35Mix3=34.70

Mix1=38.62KgMix2=39.44Mix3=41.90

7 Plantedcarrier,(70%soil-30%pumice)

- 1.Ivy=36.72Kg2.Spider=35.14Kg3.Pilea=45.54Kg4.Creep.fig=42.36Kg5.Fern=40.74Kg6.Gold.Poth.=43.86Kg

-

NoteCTA:CarrierTypeA , CTB:CarrierTypeB , CTC:CarrierTypeCMix1,2,3=tomeasureconsistencyinmeasurementsIconductedthreeexperimentswiththreeofeachcarriershavingtheexactsamemixtureofplantsspecies*Allthreesystemswereplantedwith40plants.

Eachpanel(CarrierA,CarrierBandCarrierC)wasplantedusing40pots,witha

mixtureofsixavailablespecies.Inordertoverifytheconsistencyreliabilityofthe

resultsforeachcarriertypethreesetsofexperimentswereconductedforeachof

thethreetestsamples.Intotal9setsofexperimentswereconductedtomakesure

theresultsareconsistentandrepeatable.Theresultsarediscussedinsection5.2.2

(Figure53-55)andshowpromisingconsistency.

41

4.2.2. PlantsDescriptionSixavailableplantswerestudied,namelyEnglishIvy(Hederahelix),Fern

(Filicophyta),GoldenPothos(Epipremnumaureum),Pilea(Pileamicrophylla),Spider

Plant(Chlorophytumcomosum‘Variegatum’)andCreepingFig(Ficuspumila).The

selectedspeciesdifferintheirproperties(leafthickness(mm),leaflength(mm),leaf

area(mm2),leafmasslive(mg),leafmassdry(mg),stemdiameter(mm),plant

height(mm)),andwillfacilitatetheexaminationofdifferentplantproperties’

impactonsoundabsorptionandscattering.Figure29illustrateseachspecies,figure

30illustratesthevarianceinplantstructureandfigure31illustratesthevariancein

plantleafs.Followareshortplantdescriptions;

ShortplantsdescriptionIvy

Ivieshavedark-green and waxy leaves, alternately arranged along the stems,Ivy

growswellinsandy,clayandnutrient-poorsoils.Itgrowsto235mminheight,with

stemsupto1.6mmindiameter,inheightinlivingwallsystems[28].

Fern

Fernsaregreenflowerlessplantswithdividedleavesthattendtogrowindamp,

shadyareas.Itgrowsto514mmheight,withstemsupto1.47mmindiameterin

livingwallsystems[28].

GoldenPothos

GoldenPothosisapopularhouseplantintemperateregions.Theplantgrowsto318

mmheight,withstemsupto4mmindiameter,climbingbymeansofaerialroots

whichadheretosurfaces.Thisplantproducestrailingstemsandrequireslittlecare.

[28].

42

Pilea

Pileahavepeculiarlypuffyleaveswithdepressedveins.Theyrequiredlowlight

levels.MostPilea(Glauca)grownomorethan299mmtall,withstemsdiameterup

to1.1mm.[28]

SpiderPlant

TheSpiderPlantisoneofthemostcommonhouseplants.Itiseasilygrownandis

especiallypopularfortheeaseandspeedwithwhichitformsnewplants.Spider

Plantsgrowquicklyto475mmheightinlivingwallsystems.[28]

CreepingFig

CreepingFigisawoodyevergreenvineandpopularhouseplantincoolerareas.It

growsto262mmheight,withstemsdiameterupto1.4mm.[28]

a) English Ivy

b) Fern

c) Golden Pothos

d) Pilea

e) Spider Plants

f) Creeping Fig

Figure29.Imagesofthevariousspeciesusedforplantingthelivingwallpanels.

43

Figure30.Sixspeciesunderinvestigation(inpot)

Figure31.Shapeoftheleafofeachspecies

4.2.3. PlantPropertiesTheplantspeciesarecharacterizedintermsof

§ Leafthickness(mm)

§ Leaflength(cm)

§ Leafarea(mm2)

§ Leafmass(live)mg

§ Leafmass(dry)mg

§ Stemdiameter(mm)

§ Plantheight(mm)

§ Leafareaindex(LAI),whenplanted

§ Totalcoverage,whenplanted

44

4.3. MeasurementprocedureofplantpropertiesPlantpropertiesweredeterminedfromanaverageofthreepotsofeachspeciestype

selectedrandomlyfromtheplantsreservedfortheresearchproject.Thethickness

oftheleaveswasdeterminedusingadigitalcaliper.Leafareawasmeasuredfrom

randomlyselectedleavesfromeachspecies.Theleavesweretracedandimportedto

AutoCADandtheareawasdeterminedwithapolyline.Leafmasswasmeasuredby

dryandliveweight.Forlivemassallselectedleafswereweightedusingascalewith

theaccuracyof0.00g(a100…ofagram)andaveraged.Todeterminedrymass,

theleaveswereblottedtoremoveexistingfreesurfacemoisture,driedinanoven

overnight(around105oF)andthenweighted.Stemdiameter(mm)wasmeasured

usingadigitalcaliper.Plantheight(mm)wasmeasuredwitharulerfromthebase

substratetotheheightofthetallestleafineachpot.LeafAreaIndex,definedasthe

areaofleavesoversurfacearea.

Scaledmeasurementsofplants

Inordertoconsidertheuseofplantsforsoundscatteringmeasurementofthe1/3

scalemodelinfrastructure,theplantcharacteristicsweremeasuredrepeatedlyover

time,astheplantschangedwithgrowth.Theresultsofallmeasurementswere

comparedtotheresultofthefully-grownspeciescharacteristics.Fromthis

investigation,itwasdeterminedthatitwasonlypossibletoscaletheplantspecies

intermsoftheliveleafmass.Inthismanner,a1/3-scaledplantwasdeterminedfor

scaledacousticmeasurements.

45

Figure32illustratestheprocessoftheestablishmentoftheplantsinthelivingwallsystems.

Figure32.PreparationphaseattheCenterforArchitecturalEcology(BCIT).Thelivingwallpanelsweredeveloped

asjointexperimentset-upwithIvanCheung(UBC,Theimpactoflivingwallsonindoorairquality).

46

4.3.1. AbsorptionAbsorptioncoefficientweremeasuredandcalculatedbasedonISO354[13]and

ASTMC423-08ainareverberationchamberof88m3atBCITFigure33.The

chamberwidth,length,heightratiois1:1.29:1.56asperASTME90-98.Theroom

wasdesignedtocreateadiffusesoundfieldwithauniformdistributionofacoustic

energyandrandomdirectionofsoundincidenceoverashorttimeperiod.According

tostudybyConnellythelow-frequencycutoffofthechamberis177Hz[7].Spatial

variationofSPLisshowntobewithin1.5dBatallfrequenciesabove177Hz.The

changeofimpedanceattheboundaryoftheconcreteroomsurfacesbetweenairand

concreteissolargethatalmostalloftheacousticenergythatisincidentonthe

roomsurfacesisreflectedbackintotheroom.Duetothediffusedsoundfieldand

theuseofabroadbandsoundsource,theresultingsoundfieldcontainsacoustic

energyacrossthewholeaudiblerange.Theabsorptionoftheroomanditscontent

soundfieldiscalculatedbasedontheassumptionsthattheincidentsoundfieldis

diffusebeforeandduringdecayandthatnoadditionalenergyenterstheroom

duringdecay[2].Inthisstudysetupthelow-frequencycutoffwasdeterminedtobe

315Hz.

Soundabsorptionareafunctionoffrequencyandmeasurementswillbemade

acrossaseriesoffrequencybands,inone-third-octavebandsfrom177Hzto4000

Hz.Asstatisticalmodeltheresultofeachtestisfromaveraging50measurements

(n=50).

Photocredit:commons.bcit.ca

Figure33.ReverberationChamberatBCIT

47

Figure34.Microphone(X)andsource(S)positionplan

Tofindtheabsorptioncoefficient,RTwasdeterminedwithimpulseresponse

measurementusingWinMLSsoftware.Thesetestmethodsdeterminethesound

absorptioninareverberationroombymeasuringdecayrate.Thesoundabsorption

wasmeasuredbeforeandafterplacingthetestspecimeninthechamber.According

toBibbysstudychangesintemperatureandrelativehumidityduringtheRT

measurementscanhaveasignificantimpactonthetestresults[42].Therefore,all

attemptsweremadeforthemeasurementstobecompletedundersimilarclimatic

conditions,andvarianceintemperatureandRHisaccommodatedduringpost-

measurementanalysis.Soundabsorptionwasalsomeasuredinaprocessof

obtainingthescatteringcoefficientat1/3scaleandisdiscussedinthefollowing

section.Asillustratedinfigure34,absorptionofeachsamplewasaveragedover50

measurements;(eachsetofmeasurementweretakenatfivedifferentpoints,every

pointhasthreespotswithdifferentheight,andthewholemeasurementateach

pointwasdonetwice).SeeAppendix4forequipmentlistandspecifications.

5.34

5.58

3.56

S

0.50

0.90

1,2,3,4,56,7,8,9,10

11,12,13,14,1516,17,18,19,20

21,22,23,24,2526,27,28,29,30

31,32,33,34,3536,37,38,39,40

2.23

3.42

4.46

1.00

2.00

3.00

4.00

0.90

1.78

2.66

3.56

41,42,43,44,4546,47,48,49,50

0.50

S

0.50

0.90

1,2,3,4,56,7,8,9,10

11,12,13,14,1516,17,18,19,20

21,22,23,24,2526,27,28,29,30

31,32,33,34,3536,37,38,39,40

2.23

3.42

4.46

0.90

1.78

2.66

3.56

41,42,43,44,4546,47,48,49,50

0.50

48

Acousticalabsorptionofeachcomponentoftheinteriorlivingwallwascalculated

fromtheSabineformula(seeEquation1).

A=A2–A1Equation7

A=Absorptionofthespecimen,m2

A1=Absorptionoftheemptyreverberationroom,m2

A2=Absorptionoftheroomafter

α=(A2–A1)/S+α1Equation8.

Inordertoaccessthelivingwallandinvestigatethecontributionofeachcomponent

(carrier,substrate,plant)aseriesoftestswereexecuted.Thefirstseriesevaluateda

singleemptypanelofeachsystem.Thesecondseriesevaluatethesinglepanelof

eachsystemfilledwithsubstrate.Theabsorptionoftwodifferentsubstratemixesin

theCarrierAandCarrierBwereevaluated.Alsotwolevelsofmoisturecontentwere

evaluatedfortheCarrierAandcarrierCfilledwithsubstrate.Thethirdseriesof

testsevaluatedeachsystemwithamixofallsixspecies.AlsoCarrierBwasplanted

witheachofthesixspeciesindividuallytoassesstheabsorptionofeachplant

species(Section5.2.2Figure57).Inthisseriesthepanelswereevaluated

individuallyandingroupsof3CarrierApanels,4CarrierBpanelsand8CarrierB

panelsinordertoconsidertheeffectofpanelsmultiplierinsoundabsorption

(Appendix5).InthattheareadoesnotmeetASTM423standardforsamplesize.

ThedataispresentedascomparativeinDSabine.

Intoaccesstheconsistencyofthemeasurements

Eachpanel(CarrierA,CarrierBandCarrierC)wasplantedusing40pots,witha

mixtureofthesixavailablespecies.Inordertoverifytheconsistencyandreliability

49

oftheresultsforeachcarrierthreetestsampleswereestablished.Foreachcarrier

typethreesetsofmeasurementwereconducted(Mix1,Mix2,Mix3).Intotal9setsof

measurementwereconductedtoensurethattheresultsareconsistentand

repeatable.TheresultsarediscussedinSection5.2.2(Figures53-55)andshow

promisingconsistency.ThisseriesofevaluationsaresummarizedinTable2.

Table2. Tableoftestinthereverberationchamber-fullscaleabsorptiontest

Test

No.

Description ASTMC423-08 Species

1 Empty reverberation chamber - 2 Turning table (1/3 scale) -

Carrier panel 3 Carrier Type A (CTA) - 4 Carrier Type B (CTB) - 5 Carrier Type C (CTC) -

Carrier panel with substrate 6 CTA with Substrate (S1: mixing rate of pumice / pot soil =

20%/80%) -

7 CTA with Substrate (S2: mixing rate of pumice / pot soil = 30%/70%)

-

8 CTB with Substrate (S1) - 9 CTB with Substrate (S2) - 10 CTC with Substrate (PS) 11 CTA with Substrate (S2),field Capacity 12 CTC with Substrate (PS), Fieled Capacity

Fully established panels 13 CTA, S2 (Sample 1) Mix1 14 CTA, S2 (Sample 2) Mix2 15 CTA, S2 (Sample 3) Mix3 16 All three CTA Mix 17 CTC, S2 (Sample 1) Mix1 18 CTC, S2 (Sample 2) Mix2 19 CTC, S2 (Sample 3) Mix3 20 CTB, S2 (Sample 1) Mix1 21 CTB, S2 (Sample 2) Mix2 22 CTB, S2 (Sample 3) Mix3 23 CTB, S2 P1= English Ivy 24 CTB, S2 P2= Fern 25 CTB, S2 P3= Golden Pothos 26 CTB, S2 P4= Pilea 27 CTB, S2 P5= Spider Plants 28 CTB, S2 P6= Ficus pumila 29 4 CTB Mix 30 8 CTB Mix

Note 1 - 10 times in 5 microphone location

50

4.3.2. Scattering

Measurementsforrandom-incidencescatteringcoefficientwerecarriedout

accordingtoISO17497-1[12]inthereverberationroom.TheBCITreverberation

chamberis88m3therefore,scatteringmeasurementsareconductedat1/3scale.

The1/3scaledturningtablethatwasbuiltaccordingtostandardasshownin

Appendix3[45]

Aperiodicpseudo-randomnoisesignals(MLS)isusedtogaintheimpulseresponse.

RTsinone-thirdoctavebandswereaveragedover50source-receiverpositions

(Figure34and36).Thedurationofthemeasurementforeachsource-receiver

positionwasequaltoonecompleterotationoftheturntable(60secondsforone

completerotationoftheturntable).Theimpulseresponsewasevaluatedbasedon

ISO354(usingthecalculatedvaluesforT1,T2,T3,T4).Reverberationtimeofthe

emptyroom(T1)andthereverberationtimewiththesampleintheroom(T2)was

measuredonanon-rotatingturntable.Additionally,thereverberationtimewhen

theturntableisrotating(T3)andwhiletheroundtableisrotatingwiththetest

sample(T4)wasmeasured.

Thescatteringcoefficient,s,wascalculatedasfollows:

αS=55.3V/S(1/c2T2–1/c1T1)Equation9.

αspec=55.3V/S(1/c4T4–1/c3T3)Equation10.

Where:

αs=random-incidenceabsorptioncoefficient

αspec=random-incidencespecularabsorptioncoefficient

V=volumeofthereverberationroom(m3)

c=speedofsound(m/s)

T20=reverberationtime

51

4.3.3.ScatteringMeasurementsInordertoinvestigatetheimpactofthetypeofspeciesandthedensityofvegetation

inthesoundabsorptionandsoundscattering,theseriesoftestswereexecutedand

listedintable3.

Toensuretheaccuracyofanysamplethescatteringcoefficientofthebaseplatewas

firstmeasured,toconfirmthatitislowerthanthespecifiedmaximumfrequency-

dependentscatteringcoefficientfrom160to4000HzaccordingtoISO17497-1

[12].Figure35showsthatthescatteringcoefficientofthebaseplateiswellbelow

theISOcriteria.Figure36illustratesthelocationofthebaseplate,microphone

positionsandsoundsourceforthescaledmeasurements.

Investigationdeterminedthatthesubstrateeffectinscatteringisnegligible

thereforeitcouldactasabaseplate.

ThescatteringcoefficientofSubstrate(30%pumice,70%pottingsoil)Inordertocalculatescatteringfromplantsfoliagewhileplantedinsubstrate,itwas

necessarytoverifythatthesubstrateconformswiththestandardcriteriaforabase

plate(turningtable).Illustratedinfigure35.AccordingtoISO17497-1[12],the

scatteringcoefficientforabaseplateusedinmeasurementshouldnotexceedthe

maximumplottedinFigure35.Asthefigureillustratestheturningtable,covered

with100mmofsubstrate,meetsthestandardcriterion;asthebaseplateforallour

scatteringexperiments.

52

Figure35.ScatteringCoefficientofbaseplateandsubstrate(30%pumice,70%soil)

Figure36.Microphone,turningtableandsourcepositionplans

Whenscatteringcoefficientsaredeterminedthroughscaledmeasurement,all

aspectsoftheexperimentalset-upmustbescaled,thisincludesthematerialunder

testandthesoundwavelengths.Themeasurementsweremadefrom160Hzto

3150Hz.160Hzisthelowfrequencylimitofthereverberationchamber,these

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

130 1300

ScatteringCoefficient

Frequency(Hz)

sbase(1/3scaled) sSubstrate30%-70% ISOmaximum

16020025031540050063080010001250160020002500231504000

3.56

4.46

S

0.50

0.50

R0.63

12

3

S2

0.50

0.50

1.79

2.25

53

measurementsrepresentthefullscalefrequencyrangeof583Hzto10000Hz.

Theplantscannotbescaled,howevertheplantspeciesevaluatedatspecifictime

periodsgrowingwithrespecttoscalingthesematerials.Afterfullgrowththe1/3

scaleplantwasdeterminedandthemeasureddatawasusedforanalysis.

Toexaminetheeffectofvegetationcoverageonsoundabsorptionandsound

scatteringcoefficient,coveragewasgraduallydecreasedbyremovingplantswhile

keepingthedistributionofplantsevenacrossthesubstratesurface.Sound

absorptioncoefficientsandscatteringcoefficientsweremeasuredforthreelevelsof

vegetationcoverageontopoftheturningtable:112plantsplantedin4-inchpots

(100%ofmaximumcoverage);56plants(50%coverage);and28plants(25%

coverage)(Figure37).Thesectionofthesamplearrangementontheturningtable

(baseplate)isshowninfigure38.

Table3. Table of test in the reverberation chamber- 1/3 scaled

Test No.

Description ISO 17497-1 Species

31 Empty Table - 32 S2 with - 33 S2 -100% cov P1= English Ivy 34 S2 -100% cov P2= Fern 35 S2 -100% cov P3= Golden Pothos 36 S2 -100% cov P4= Pilea 37 S2 -100% cov P5= Spider Plants 38 S2 -100% cov P6= Ficus pumila 39 S2 - 50% cov P1= English Ivy 40 S2 - 50% cov P2= Fern 41 S2 - 50% cov P3= Golden Pothos 42 S2 - 50% cov P4= Pilea 43 S2 - 50% cov P5= Spider Plants 44 S2 - 50% cov P6= Ficus pumila 45 S2 - 25% cov P1= English Ivy 46 S2 - 25% cov P2= Fern 47 S2 - 25% cov P3= Golden Pothos 48 S2 - 25% cov P4= Pilea 49 S2 - 25% cov P5= Spider Plants 50 S2 - 25% cov P6= Ficus pumila

Note - In 50 microphone location - S2: Substrate with mixing rate of pumice / pot soil = 30%/70%

Data of table 1 & 2 collected at each above test.

55

MeasurementAccuracyThemeasurementofeachsampleusedtodeterminethescatteringandabsorption

coefficientsisfromtheaverageofthemeasurementstakenfromseveral

microphonepositions.Inordertochangethemicrophoneposition,openingofthe

door,toenterthechambercreateschangesintemperatureandhumidity.

Measurementishighlysensitivetotemperatureandrelativehumidityfactors,

especiallyathighfrequencies[44].Givenuncertaintyinthemeasurementswhich

comesfromthelimitedcontroloverthetemperatureandhumidityinthe

reverberationchamber,theaccuracyofthemeasurementswasincreasedbywaiting

forapproximately30minafterclosingthedoortoallowthetestspecimenstoadjust

tothetemperatureandhumidityinthereverberationchamber.

56

5. Result

5.1. Plantproperties(Physicalpropertiesoftheplantsstudied)TheTables4,5and6illustratetheplantpropertiesofeachspeciesbasedonplant

growthduring6months.Plantpropertieswereevaluated4timesover6monthsas

describedinmethodssection,thetime-determinedplantpropertiesarelistedin

Table4.

Bycomparingthemeasurementsoftheplantpropertiesmeasurements(leaf

thickness,leaflengthandetc.)over6months(T1,T2,T3)withfullygrownplant

propertymeasurements(T4)itwasdeterminedthatthespecieswereat1/3-scaleof

thefullygrownspeciesattimeT2.Comparingtheplantpropertiesforfull-scale(at

T4)and1/3-scale(atT2)setsofmeasurementsinTable4,indicatesthatthemass

oftheplantsscaledequallywithtimeforall6speciesandthattherewasno

correlationbetweenthepropertiesotherthantheirliveanddrymass.TheLeafArea

Index(LAI)hasbeenmeasuredonlyfor1/3-scalespecies(T2),asallmeasurements

atturningtablewasdoneat1/3-scale.

ThesoundabsorptionmeasurementsforthelivingwallsandtheLAIcalculations

(Table6)werecarriedoutonlyforthefullscalespecies(atT4).

57

Table4.Thecharacteristicsofplantleafspecimen

No. Plants characterization

Plant Species

Leaf

thickne

ss

(mm)

Leaf

length

(cm)

*Leaf

area

Index

(LAI)

Leaf area

Average

(mm2)

Leaf

mass

(live)

mg

Leaf

mass

(dry)

mg

Stem

diameter

(mm)

Plant

height

(mm)

10 English Ivy -T1 0.34 3 0.0009 0.01 1.19 124

11 English Ivy -T2 (1/3

scale)

0.379 3 154.54 0.001 0.09 0.02 1.36 177.96

12 English Ivy -T3 0.391 43 - 0.0012 0.03 1.52 184

13 English Ivy –T4 0.4 5 - 0.0013 0.22 0.04 1.6 235

14 Fern -T1 0.3 4 - 0.005 0.007 1 109

15 Fern -T2 (1/3 scale) 0.338 5.5 505.48 0.007 0.08 0.01 1.073 199.92

16 Fern -T3 0.666 1 - 0.001 0.02 1.321 228

17 Fern -T4 0.68 1.5 - 0.002 0.21 0.03 1.47 514

18 Golden Pothos -T1 0.52 6 - 0.0019 0.042 2.221 176

19 Golden Pothos -T2

(1/3 scale)

0.582 7.7 48.29 0.003 0.52 0.06 2.942 240

20 Golden Pothos -T3 0.63 9.2 - 0.0038 0.09 3.6 291

21 Golden Pothos -T4 0.65 1 - 0.004 1.26 0.15 4 318

22 Pilea -T1 0.45 1 - 0.00017 0.013 1 120

23 Pilea -T2 (1/3 Scale) 0.492 1.7 814.57 0.0002 0.04 0.02 1.02 135.9

24 Pilea -T3 0.527 2.2 - 0.00022 0.034 1.612 237

25 Pilea -T4 0.53 2.5 - 0.00023 0.11 0.04 1.1 292

26 Spider Plants -T1 0.44 1.1 - 0.003 0.02 - 166

27 Spider Plants -T2

(1/3 Scale)

0.495 18.8 141.66 0.0034 0.79 0.06 - 216.45

28 Spider Plants -T3 0.741 3.9 - 0.004 0.15 - 383

29 Spider Plants -T4 0.9 5 - 0.0048 2.44 0.19 - 475

30 Creeping Fig -T1 0.31 1 - 0.00036 0.081 1.197 98

31 Creeping Fig -T2

(1/3 Scale)

0.319 2 643.93 0.00040 0.04 0.01 1.215 135

32 Creeping Fig -T3 0.331 2.7 - 0.00052 0.016 1.35 195

33 Creeping Fig -T4 0.34 3 - 0.00056 0.07 0.02 1.4 262

Note - T1, … Tn (max; n=4) to be determine base on plant growth during

6 months period

*Leaf Area Index of each species at the turning table

59

Table6.TheCharacteristicssurfaceareaofplants

No. Sample Leaf area Index (LAI) of planted

carriers

1 CTA (CarrierTypeA), mix plants 224

2 CTB (CarrierTypeB), mix plants 561

3 CTC (CarrierTypeC), mix plants 652

4 CTB, S2 with P1(EnglishIvy) 574

5 CTB, S2 with P2(Fern) 1744

6 CTB, S2 with P3(GoldenPothos) 583

7 CTB, S2 with P4(Pilea) 678

8 CTB, S2 with P5(SpiderPlants) 1699

9 CTB, S2 with P6(Ficuspumila) 894

Note S2:Substratewithmixingrateofpumice/potingsoil=30%/70%

60

5.2. AbsorptionandScattering

5.2.1. AbsorptionofEmptyRoom:

Thechamberishighlyreverberantandabsorptionofthechamberincreases

insignificantlywithincreasingfrequency. Figure39showsabsorptiontotalinSabine

oftheemptyreverberationchamber.Thesoundabsorptionofthereverberation

chamber(Figure39)islessthan0.08Sabineforfrequenciesbetween177and4000

Hz.

Figure39.Absorption(Sabine)ofemptyreverberationchamber

0

0.5

1

177 1770

Absorption(Sabine)

One-ThirdOctaveBandsFrequency(Hz)

2002503154005006308001000125016002000250031504000

61

5.2.2. Absorptionoflivingwallsystems:

TheabsorptionforallfullscalemeasurementsareinSabineunits.Thefirstsetof

resultsisforasinglepanelofeachcarriertype(Figure40),thesecondsetisofthe

singlepanelofeachcarriertypewithtwodifferentmixturesofsubstrates(Figure

43),andthirdsetisofthefullyestablishedvegetatedlivingwallsystemsofeach

carriertype(e.g.Figure48).Itshouldbementionedthatwiththehighabsorptive

sampleintheroomtheroomisnolongerdiffusearound315Hzwhichgenerated

artificialresults.

EmptylivingwallCarrierpanelFigure41comparestheabsorptionofthreeemptypanelsconstructedwithvarious

materialsandgeometry:CarrierA,CarrierBandCarrierC.Theoveralltrendisthe

sameforall;theabsorptionrisesslightlyfromlowtohighfrequency.Theempty

CarrierChasahigherabsorptivitythanCarrierAandCarrierBatfrequenciesbelow

1600Hz.TheabsorptionofCarrierAandCarrierBfollowsthesametrend,whilethe

CarrierBsystemismoreabsorptiveatfrequenciesabove500Hzanditsabsorption

increaseswithfrequency.

(a)

(b)

(c)

Figure40.Themeasurementconditionofrandom-incidentAbsorptionofthreedifferentemptylivingwallpanels;(a)CarrierA,((b)CarrierB(c)CarrierC

62

Figure41.Comparisonofabsorption(DSabine)ofemptycarriers

0

1

2

3

4

177 1770

Absorption(DDSabines)

One-thirdOctaveBandsFrequency(Hz)

EmptyModuloGreenCarrier EmptyPlantConnectionCarrier EmptyEverGreenCarrier

2002503154005006308001000125016002000250031504000

EmptyCarrierA EmptyCarrierB EmptyCarrierC

1

LivingwallscarrierpanelwithsubstrateThepresenceofsubstratessignificantlyaffectstheabsorptivecapacityofthe

carrier.Figure42illustratesabsorptionofthelivingwallcarriersfilledwith

substrate.Theoveralltrendshowsincreasingabsorptionwithfrequency.Atmid

frequencythesystemhassimilarabsorption.Atfrequenciesabove1770Hz,the

carrierBisthemostabsorptive.ThetrendofthegraphsofCarrierAandCarrierB

aresimilartoeachotherstartingat800Hz.Whilefollowingthesametrend,the

absorptioncoefficientofCarrierAisabout0.2morethanCarrierCatallfrequencies

from800Hzto4000Hz.RecallthatCarrierCisahydroponicsystem.Thissystem

hasanominalamountofpottingsoilinit,whichisonlythesoilthatcomeswiththe

plantsfromthe2-inchpots.(RefertoSection4.4fordetailedspecificationsofeach

carriersystem.)

Figure42.Comparisonofabsorption(DSabine)ofcarriersfilledwithsubstrate

0

1

2

3

4

177 1770



MGCarrier&Sub30%,70% PCCarrier&substrate30%70% EG&PottingSoil

20025031540050063080010001250160020002500 31504000

CarrierA&Sub30%/70% CarrierB&Sub30%/70% CarrierC&pottingsoil

1

Carrierswithadifferentmixtureofsubstrate

Therandom-incidenceabsorptionoftwomixturesofsubstrateswasmeasured:(a)

20%pumiceand80%pottingsoil,(b)30%pumiceand70%pottingsoil(Figure

43).Figure44&Figure45illustrateoverallincreaseinabsorptionduetothe

substratemixturesinCarrierAandB.TheCarrierCwasnotevaluatedwith

differentmixturesofsubstrate.AspreviouslyexplainedinSection4.4,itisnot

possibletoaddsubstratetoCarrierC.Inallcases,theabsorptionoftheempty

carrierisshownasthebaseline.

Itshouldbenotedthatthevolumeofthecarrierpanelsarenotsame.The

percentageofmoistureinthesubstratemixtureswasthesamebutwasnot

quantified. However,thedifferenceinthemixtureofthesubstratedoesnotmakea

noteworthydifferenceintermsofabsorptionofCarrierA.InCarrierBtheaddition

ofsubstrateincreasedabsorptionbyapproximately0.5Sabins.Theabsorptionof

themixturewithahigherpercentageofsoil(80%)isonlyslightlymorethanthe

absorptionofthesecondmixture(70%soil)formostfrequencies(Figure45).

(a)

(b)

Figure43.Themeasurementconditionofrandom-incidentAbsorptionoftwodifferentmixturesofsubstrate;

(a)20%pumice,80%pottingsoil,(b)30%pumice,70%pottingsoil)

65

Figure44.Comparisonofabsorption(DSabine)ofcarrierAfilledwithsubstrate

Figure45.Comparisonofabsorption(DSabine)ofcarrierBfilledwithsubstrate

0

1

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3

4

177 1770



MGCarrier&Sub20%,80% MGCarrier&Sub30%,70% EmptyMGCarrier

20025031540050063080010001250160020002500 31504000

CarrierA&Sub20%/80% CarrierA&Sub30%/70% EmptyCarrierA

1

0

1

2

3

4

177 1770



Carrier&Substrate20%80% Carrier&substrate30%70% EmptyPCCarrier

2002503154005006308001000125016002000250031504000

CarrierB&Sub20%/80% CarrierB&Sub30%/70% EmptyCarrierB

1

66

Theeffectofmoistureinthesubstrate

Theeffectoftheamountofwaterinthesubstratewasinvestigatedonasinglepanel

whichrequiressubstraterepresentedbyCarrierAandCarrierC,whichhasroomfor

onlyasmallamountofpottingsoil(Figure46and47).Drysubstratemixture

30%/70%forlivingwallwastakendirectlyfromthebaginwhichthemixturewas

stored.Thereisanominalamountofmoisture(unquantified)inthis“dry”substrate

comparedtothelivingwallcarrierwithsubstratein“fieldcapacity”.Fieldcapacityis

establishedbysaturatingthesubstrateandallowingthesubstratetodrainfor24

hours.

Figure46showstheabsorption(Sabine)forCarrierAfilledwithdrysubstrateand

withsubstrateatfieldcapacity.Thetrendslookverysimilarbefore630Hz.The

absorptivityincreaseswithfrequenciesforbothcases.After630Hz,thedrier

substratemixabsorbssignificantly(about0.5Sabine)moresoundthanthe

substrateinfieldcapacity:Thisdifferenceis0.3Sabineat1000Hzandincreasesto

about0.6around2000Hzandincreasesto1Sabineat400Hz.

Figure47illustratesthattheemptyCarrierChascomparable;andevenhigher

absorptionthanthecarrierwithsubstrate.after800Hzthetrendsaresimilar

(increasingwithfrequency).AndthedrierCarrierCisabout0.2Sabinemore

absorptivethancarrierCinfieldcapacity.

67

Figure46.Comparisonofabsorption(DSabine)ofCarrierAfilledwithsubstrate(30%/70%mix);dryandinfield

capacity

Figure47.Comparisonofabsorption(DSabine)ofcarrierCfilledwithsubstrate(30%/70%mix);dryandinfieldcapacity

0

1

2

3

4

177 1770



MGCarrier&Sub30%,70% MGCarrier&Sub30%70%infieldcapacity

MGEmptyCarrier

2002503154005006308001000125016002000250031504000

DryCarrierA&Sub30%/70% CarrierA&Sub30%/70% infieledcapacity

EmptyCarrierA

1

0

1

2

3

4

177 1770



EG&PottingSoil EGinFieldCapacity EG-EmptyCarrierEG&DryPottingSoil

2002503154005006308001000125016002000250031504000

DryCarrierC&PottingSoil CarrierCinfieledcapacity EmptyCarrier

1

68

VegetatedlivingwallpanelsThegraphsinthissectionshowabsorptionpatternsofthethreelivingwallsystems

plantedwithamixtureofsixspeciesIvy,CreepingFig,SpiderPlant,Pilea,Fernand

GoldenPothos.Figure48illustratesthesinglepanelvegetatedlivingwallsinthe

reverberationchamber.Amixtureofthethreeplantspecimensisgrownineachof

thecarriersystemsA,BandC.

Figure49illustratesthedifferencebetweentheabsorptionoftheCarrierAfilled

withsubstrateandplantedCarrierA.Plantsaddedtothesubstratedonotincrease

theabsorptionofthelivingwallsystemabovesubstrateonlypanels.Moreover,

absorptiondecreaseswithvegetationabove1000Hz,butitisstillhigherthanthe

emptypanelusedasareference.Above1000Hztheplantsdiminishtheabsorption

ofthepanelprovidedbythesubstrate.Thediminishingabsorptionincreaseswith

frequency. Figure50illustratesresultsimilartoFigure49,theabsorptionofthe

carrierBwithandwithoutthevegetationisveryclosebelow1600Hzfrequency.

Above1600Hzpanelthecarrierfilledwithsubstrateismoreabsorptivethanthe

vegetatedpanel,above2500Hztheabsorptionofthevegetatedpanelisevenless

thantheemptycarrierpanelitself. Below1600Hztheneteffectofplantson

absorptionofCarrierCisnotclear. Figure51indicatesthattheabsorptivityabove

1000HzofCarrierCdoesnotchangebyaddedpottingsoilandvegetation.The

vegetatedCarrierCisasabsorptiveastheemptypanel,especiallyathigh

frequencieswherealltrendsarethesame.

69

(a)

(b)

(c)

Figure48.Themeasurementconditionofrandom-incidentAbsorptionoftheplantedlivingthreedifferentlivingwallsystems;(a)CarrierA,(b)CarrierB,(c)CarrierC.(40planteachpanel)

Figure49.Comparisonofabsorption(DSabine)ofCarrierAnempty,withsubstrateandvegetated.

0

1

2

3

4

177 1770



MGCarrier&Sub30%,70% MGMixVegitated(Avegare)

EmptyMGCarrier

2002503154005006308001000125016002000250031504000

CarrierA&Sub30%/70%

EmptyCarrierA

CarrierA,MixVegetated

1

70

Figure50.Comparisonofabsorption(DSabine)ofCarrierBempty,withsubstrateandvegetated.

Figure51.Comparisonofabsorption(DSabine)ofCarrierCempty,withsubstrateandvegetated.

0

1

2

3

4

177 1770



Carrier&substrate30%70% EmptyPCCarrier 1PannelMix-Vegetated(Average)

2002503154005006308001000125016002000250031504000

CarrierB&Sub30%/70% EmptyCarrierB CarrierB,Mixvegetated

1

0

1

2

3

4

177 1770



EG&PottingSoil EGMixVegetated(Average) EG-EmptyCarrier

2002503154005006308001000125016002000250031504000

CarrierC&PottingSoil CarrierC,MixVegetated EmptyCarrierC

1

71

Figure52comparestheabsorptivityofeachlivingwallsystem.Theaverageof

measurementoftheresultsfrom3plantedsinglelivingwallpanelswiththemixof

specieswasusedforeachsystem(CarrierA,B&C).Above1000Hz theabsorption

ofallthreesystemsareminimaldifferentintrend.Below1000HzsystemAhas

about0.5SabinehigherabsorptionthansystemsBandC.

CheckingfortheconsistencyoftheresultsAsdiscussedinsection4.5.1.1measurementareconductedtoverifytheconsistency

oftheresults.Threeofeachcarriersystemsareplantedwiththesamemixof

speciestoexaminetheconsistencyandrepeatabilityofresults. Figure53presents

thatallthreemixedvegetatedCarrierAsamples(in30%,70%carrier)havethe

sameabsorptionatlowerandmidfrequency.Thisshowsconsistencyof

measurementsfortheCarrierAthatwasplantedwiththesamemixtureofspecies.

Similarly,Figure54showsthattheCarrierBtrendsareveryclosetoeachotherbut

onepanel(Mix1)islessabsorptiveafter1600Hz(0.6Sabinelessthantheother

two.). AccordingtoFigure55,resultsshowminorabsorptiondifferencesbetween

thecarrierCpanels.Thehighfrequencydifferenceinabsorptionofthethree

samplesofthesamesystemisnominallythesameasthedifferenceoftheaverage

measurementofthethreesystem.

72

Figure52.Comparisonofabsorption(DSabine)ofthreevegetated(mixspecies)livingwallpanels

Figure53.Comparisonofabsorption(DSabine)ofCarrieranemptyandplantedpanels(Mix1,2&3).ThetestspecimensthatwerestudiedforcheckingtheconsistencyofthemeasurementsincarrierA(Section

4.5.1.1).

0

1

2

3

4

177 1770

Absorption(DDSabinses)


ModuloGreenMix(Vegetated) PlantConnectionMix(vegetated)

EverGreenMix(Vegetated)

2002503154005006308001000125016002000250031504000

CarrierA,MixVegetated

CarrierC,MixVegetated

CarrierB,MixVegetated

1

0

1

2

3

4

177 1770



Mix1(vegetated) Mix2(vegetated) Mix3(vegetated) EmptyMGCarrier

2002503154005006308001000125016002000250031504000

1

73

Figure54.Comparisonofabsorption(DSabine)ofCarrierBemptyandplantedpanels(Mix1,2&3).ThetestspecimensthatwerestudiedforcheckingtheconsistencyofthemeasurementsincarrierA(Section

4.5.1.1).

Figure55.Comparisonofabsorption(DSabine)ofCarrierCemptyandplantedpanels(Mix1,2&3).ThetestspecimensthatwerestudiedforcheckingtheconsistencyofthemeasurementsincarrierA(Section

4.5.1.1).

0

1

2

3

4

177 1770



PCMix1 PCMix2 PCMix3 EmptyPCCarrier

2002503154005006308001000125016002000250031504000

EmptyCarrierBMix1(Vegetated) Mix2(Vegetated) Mix3(Vegetated)

1

0

1

2

3

4

177 1770



EverGreen(EG)-Mix1 EG-Mix2 EG-Mix3 EmptyEGCarrier

2002503154005006308001000125016002000250031504000

Mix1(Vegetated) Mix2(Vegetated) Mix3(Vegetated) EmptyCarrierC

1

74

InvestigationofCarrierBwith6individualspecies(evaluationofsinglePanel)

SufficientnumberofCarriertypeBpanelsweresixfortheinvestigationoftheeffect

oftheindividualspeciesonabsorption.

Figure56showsthatthetypeofplantsaffectsabsorptivity.Thetrendsarealmost

thesame.GoldenPothoshasthehighestabsorptivityoverall.Thenextmost

absorptiveisPileawithaslightlylowerabsorptioncoefficientthanGoldenPothos

throughthefrequencyband.CreepingFig,SpiderPlant,mixplantedpanelandFern

aresimilarintermsofabsorptionatmidfrequencies(630-1000Hz).After1000Hz,

thedifferenceintheabsorptivityofCreepingFig,SpiderPlant,mixvegetatedismore

significantandincreaseswithfrequency.ThetrendforFerndoesnotincreasewith

frequencybetween6300and2500Hz.Themixplantedpanelisapanelusinga

combinationofsixspecies(SpiderPlant,Ivy,Pilea,CreepingFig,GoldenPothosand

Fern)intheFigure56,anditsabsorptivityissomewherebetweentheother6

species.

Figure56.Comparisonofabsorption(DSabine)ofvegetatedCarrierBpanel

0

1

2

3

4

177 1770

Absorption(DDSabine)


Spider IVY Pilea

CFig GoldenPothos Fern

EmptyPCCarrier PCMixVegetated(averaged)

2002503154005006308001000125016002000250031504000

CarrierB,MixVegetatedCarrierB,Empty

1

75

5.2.3. AbsorptionevaluationofamultipleofpanelsCarrierBwasagainusedforthisseriesofmeasurementtakentoinvestigatethe

effectofmultiplepanelsasitwasnotexpectedtobelinear.

Figure58showstherandom-incidentabsorption(Sabine)resultsfor1vegetated

CarrierApaneland3vegetatedCarrierApanels.Theabsorptionisconsistently

greateratallfrequencies.Atlowfrequenciesbelow500Hz,theabsorptionincreases

bymorethantwo,withtheadditionoftwomorepanels.Ontheotherhand,at

frequenciesabove500Hz,3carriersprovideaboutonefoldmoreabsorptionthana

singlecarrier.

The4-panelsampleisacombinationof3mixedplantedpanelsand1homogenous

panel.8panelsareacombinationof3mixedpanelsand5homogeneousplanted

panelsexcludingtheFernspecies(Figure57).

IllustratedinFigure59,increasingthenumberofCarrierBpanelssignificantly

increasestheabsorptionatlowfrequencies(below630Hz)andtheabsorption

resultalmostdoubledwithadoublingofthepanels.Theincreasednumberofpanels

hasagreatereffectatlowfrequencies.Above800Hz,thereatwo-foldincreasein

absorptionfrom1panelto4panels(about1Sabine)andfrom4panelsto8panels

andadditionaltwo-foldincrease.After800Hzthereisanapproximateone-fold

increasewitheachdoubledthenumberofpanels.

76

Figure57.Themeasurementconditionofthelivingwallmadeof8vegetatedCarrierBpanels

Figure58.Comparisonofabsorption(DSabine)ofmultiple,CarrierA

0

1

2

3

4

5

6

177 1770



1MGpannel 3MGPannels MGEmptyCarrier

20025031540050063080010001250160020002500 31504000

1CarrierApanel 3CarrierApanels CarrierA,Empty

1

77

Figure59.Comparisonofabsorption(DSabine)ofmultiple,CarrierB

0

1

2

3

4

5

6

177 1770



PCEmptyCarrier 1PannelMix-Vegetated(Average)

4pannelsMix-Vegetated 8PannelsMix-Vegetated

20025031540050063080010001250160020002500 31504000

CarrierB,Empty 1CarrierB,MixVegetated

4CarrierB,MixVegetated 8CarrierB,MixVegetated

1

78

5.3. 1/3ScaleMeasurements;AbsorptionandScatteringThisseriesoftestillustratetheeffectofpercentagecoverageonsoundabsorption

andsoundscattering.Recallthatmeasurementmethodataone-thirdscalewas

developed,duetothecapacityandsizeofthereverberationchamber.Additionally,

(seesection4.5.3)the1/3-scaleoftheplantsisreviewedinsection5.1.

(a)(BasePlate)TurningTable

(b)Turningtablecoveredwithsubstrate

Figure60.Themeasurementconditionof(a)Baseplateand(b)substrate100mmtopsoil

79

Figure61.Scatteringcoefficientofbaseplateandsubstrate(30%pumice,70%pottingsoil)

AbsorptioncoefficientofdifferentspeciesThissectiondiscussestheinvestigationoftheabsorptioncoefficientofdifferent

speciesasafunctionofpercentcoverage.Theevaluationmethodistobediscussed

insection6.3.2.

Figure62illustratestheGoldenPothoswithdifferentpercentagecoverage,25,50

and100%ontheturningtable.Thesamplewith100%coveragehasthehighest

absorptionthroughallfrequencies.SAAis0.31,0.31and0.37for25%coverage,

50%coverageand100%coveragerespectively.Theabsorptioncoefficientcurvefor

GoldenPothosatmidfrequenciesbetween1000and2500Hz;0.4for25%and50%

and0.45for100%coveragerespectively(Figure63).2

2GoldenPothos;NRC(25%)=0.30,NRC(50%)=0.31,NRC(100%)=0.37

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

130 1300


Frequency(Hz)

sbase(1/3scaled) sSubstrate30%-70% ISOmaximum

16020025031540050063080010001250160020002500231504000

80

(a)

(b)

(c)

Figure62.Themeasurementconditionof100mmsubstratewithGoldenPothos.(a)25%vegetationcoverage),(b)50%vegetationcoverage,(c)100%vegetationcoverage

Figure63.AbsorptioncoefficientofGoldenPothos,differentvegetationcoverage(25%,50%&100%)

Figure64illustratesIvywithdifferentcoverage25,50,100%ontheturningtable.As

showninFigure65,atmidfrequenciestheabsorptioncoefficientofIvywith100%

coverageisabout0.07higherthantheabsorptionoftheIvywith50%coverageand

25%(SAA=0.34,0.27and0.25respectively).Thedifferencebetweenthe50%and

25%coverage,isaround0.02.3

3Ivy;NRC(25%)=0.25,NRC(50%)=0.27,NRC(100%)=0.34

0

0.2

0.4

0.6

0.8

1

150 1500

Absorptioncoefficient


αs(GoldenPothos100%cov) αs(GoldenPothos50%cov) αs(GoldenPothos25%cov)

160200250315400500630800100012501600200025003150 4000

81

(a)

(b)

(c)

Figure64.Themeasurementconditionof100mmsubstratewithIvy.(a)25%vegetationcoverage,(b)50%vegetationcoverage,(c)100%vegetationcoverage

Figure65.AbsorptioncoefficientofIvy,differentvegetationcoverage(25%,50%&100%)

Figure66showstheset-upfortheabsorptioncoefficientmeasurementswithPilea.

Bycomparingthe3setsofmeasurementsinFigure67,thedifferenceinabsorption

coefficientofPileaatlowfrequenciesismoresignificantthanthedifferenceat

frequenciesabove630Hz.Thehighfrequencyabsorptioncoefficientabout800Hz

forPileaisalmostthesameforallthemeasuredcoveragepercentages. The

absorptioncoefficientsfordifferentcoveragesarewithinthesamerangeatmid

0

0.2

0.4

0.6

0.8

1

160 1600



α(Ivy100%cov) α(Ivy50%cov) αs(Ivy25%cov)

160 200 2503154005006308001000125016002000250031504000

82

frequencieswiththeSAAvaluesbeing0.34,0.34and0.4for25%,50%and100%

coveragerespectively.4

(a)

(b)

(c)

Figure66.Themeasurementconditionof100substratewithPilea.(a)25%vegetationcoverage,(b)50%vegetationcoverage,(c)100%vegetationcoverage

Figure67.AbsorptioncoefficientofPilea,differentvegetationcoverage(25%,50%&100%)

Figure68showstheset-upfortheabsorptioncoefficientmeasurementswith

CreepingFig.Results(Figure69)displayaslightdifferenceinabsorptivityof

CreepingFigwithincreaseinplantcoverage.Asshownathigherfrequencies(above

1600Hz),theabsorptivityofCreepingFigismoredependentonthedensityofthe

4Pilea;NRC(25%)=0.32,NRC(50%)=0.34,NRC(100%)=0.4

0

0.2

0.4

0.6

0.8

1

160 1600



αs(Pilea100%cov) αs(Pilea50%cov) αs(Pilea25%cov)

160 200250315400500630800100012501600200025003150 4000

83

coverage.Theabsorptiongraduallyincreaseswithincreasingcoverage.TheSAAof

theCreepingFigis0.30for25%,0.32for50%and0.34for100%plantcoverageat

4000Hz.5

(a)

(b)

(c)

Figure68.Themeasurementconditionof100mmsubstratewithCreepingFig.(a)25%vegetationcoverage,(b)50%vegetationcoverage,(c)100%vegetationcoverage

Figure69.AbsorptioncoefficientofCreepingFig,differentvegetationcoverage(25%,50%&100%)

Themeasurementset-upforabsorptioncoefficientmeasurementsofSpiderPlant

areillustratedinFigure70.AsillustratedinFigure71absorptionsforthethreesets

ofcoveragearefluctuatingbetween0.4and0.6atfrequenciesbetween630and

5CreepingFig;NRC(25%)=0.3,NRC(50%)=0.32,NRC(100%)=0.34

0

0.2

0.4

0.6

0.8

1

177 1770



αs(CreepingFig100%cov) αs(CreepingFig50%cov) αs(CreepingFig25%)

160200250315400 5006308001000125016002000250031504000

84

1000Hz.Thesoundabsorptionaverage(SAA)ofSpiderPlantis0.48,0.38and0.31

for25%,50%and100%coverage.Anduniquetothesixplantsspeciesevaluated

theSAAoftheSpiderPlantdecreaseswithincreasingcoverage,thisanomalyisnot

understood.6

(a)

(b)

(c)

Figure70.Themeasurementconditionof100mmsubstratewithSpiderPlant.(a)25%vegetationcoverage,(b)50%vegetationcoverage,(c)100%vegetationcoverage

Figure71.AbsorptioncoefficientofSpiderPlant,differentvegetationcoverage(25%,50%&100%)

Themeasurementset-upfortheabsorptioncoefficientmeasurementoftheFern

plantisillustratedinFigure72.Figure73illustratesasignificantdifferenceabout

0.2betweentheabsorptivityofFernwith25%coverageand50%coverageatall

6SpiderPlant;NRC(25%)=0.4,NRC(50%)=0.37,NRC(100%)=0.31

0

0.2

0.4

0.6

0.8

1

160 1600



αs(SpiderPlant100%cov) αs(SpiderPlant50%cov) αs(SpiderPlant25%cov)

160200250 315400 5006308001000125016002000250031504000

85

frequencies,relativetothedifferencebetween50%coverageand100%coverage.

Thesoundabsorptionaverageincreaseswithdensityoftheplants.Itis0.11,0.31

and0.33for25%,50%and100%respectively.7

(a)

(b)

(c)

Figure72.Themeasurementconditionof100mmsubstratewithFern.(a)25%vegetationcoverage,(b)50%vegetationcoverage,(c)100%vegetationcoverage

Figure73.AbsorptioncoefficientofFern,differentvegetationcoverage(25%,50%&100%)

7Fern;NRC(25%)=0.1,NRC(50%)=0.3,NRC(100%)=0.33

0

0.2

0.4

0.6

0.8

1

160 1600



αs(Fern100%cov) αs(Fern50%cov) αs(Fern25%cov)

160200250 315 400500630800 1000125016002000250031504000

86

5.3.1. Thescatteringcoefficientofplantspecieschangeswithdifferentpercentagecoverageofvegetation

Thisseriesofthetestsinthissectioninvestigatesscatteringpatternofthesix

availablespeciesandinvestigatestheimpactofthepercentagecoverageof

vegetationonsoundscattering.Theevaluationmethodisdiscussedinsection4.5.3.

InFigure74scatteringcoefficientofGoldenPothoswiththreedifferentlevelsof

vegetationcoverageisshown.Itcanbeseenthat,ingeneral,scatteringcoefficient

increaseswithfrequencyandpercentageofcoverage.GoldenPothos’saverage

scatteringcoefficientatmidfrequencies(200-2500Hz)with25%,50%and100%

coverageis0.05,0.13and0.14respectively.ScatteringcoefficientofGoldenPothos

with50%coverageisaround0.14higherthan25%,whilethereisnotmuch

differencebetweenthescatteringcoefficientat50%and100%coverage,whichis

about0.04.

AsshowninFigure75,averagescatteringcoefficientofIvy(200-2500Hz)is0.005

at25%,anditis0.01with50%coverageand0.05with100%coverage.The

scatteringcoefficientofIvyincreaseswithincreasingfrequencyandvegetation

coverage.25%and50%coverageofIvy,isalmostsameintermsofscattering

sound,100%coveragescattersmoreatfrequenciesabove800Hz.

Figure76showsthescatteringcoefficientofPileawithdifferentvegetation

coverage.Itcanbeseenthatscatteringcoefficientisalmostthesameatfrequencies

below500Hz.At100%coveragescatteringincreasesabove2000Hz.Andthe

averagesoundscatteringforPileais0.015,0.04and0.014for25%,50%and100%

coveragerespectively.

InthecaseofCreepingFig,itcanbeseenthattheoveralltrendisupwardandthe

scatteringcoefficientgraduallyincreaseswithfrequencyabove800Hz,especiallyat

87

100%coverage(Figure77).Theaveragescatteringcoefficientis0.10,0.11and0.19

at25%,50%and100%coveragerespectivelybetween200and2500Hz.

Figure78suggeststhatthescatteringcoefficientofFernwithdifferentcoverage

percentagesfluctuatesaround0.05atfrequenciesbelow630Hz.Abovethat,it

graduallyincreasesandtheaveragesoundscatteringofFernis0.05,0.06and0.17

for25%,50%and100%coveragerespectively.

Figure79showsavariationofthescatteringcoefficientcurvesofSpiderPlantover

differentfrequencies.Thedifferencesbetweenthescatteringcoefficientofthe

differentpercentcoveragesismorepronouncedthantheotherplantspecies.Inthe

lowerfrequencies,aswellastheaveragesoundscatteringofSpiderPlantis0.07,

0.05,and0.1for25%,50%and100%coveragerespectively.

Clearlyabove630Hzscatteringisincreasingwithcoverageanditisinterestingto

seeincreaseconsistencyata100%coverage.

Figure74.ScatteringcoefficientofGoldenPothos,differentvegetationcoverage(25%,50%&100%)

0

0.2

0.4

0.6

0.8

1

120 1200



s(GoldenPothos,100%cov) s(Goldenpothos50%cov) s(Goldenpothos25%cov)

1602002503154005006308001000125016002000250031504000

88

Figure75.ScatteringcoefficientofIvy,differentvegetationcoverage(25%,50%&100%)

Figure76.ScatteringcoefficientofPilea,differentvegetationcoverage(25%,50%&100%)

0.0

0.2

0.4

0.6

0.8

1.0

120 1200

Scatteringcoefficient


s(Ivy100%cov) s(Ivy50%cov) s(Ivy25%cov)

16020025031540050063080010001250160020002500 31504000

0.0

0.2

0.4

0.6

0.8

1.0

120 1200



s(Pilea,100%cov) s(Pilea,50%cov) s(Pilea,25%cov)

1602002503154005006308001000125016002000250031504000

89

Figure77.ScatteringcoefficientofCreepingFig,differentvegetationcoverage(25%,50%&100%)

Figure78.ScatteringcoefficientofFern,differentvegetationcoverage(25%,50%&100%)

0.0

0.2

0.4

0.6

0.8

1.0

120 1200



s(CreepingFig,100%cov) s(CreepingFig,50%cov) s(CreepingFig,25%cov)

160200250315400500630 8001000125016002000250031504000

0.0

0.2

0.4

0.6

0.8

1.0

120 1200



s(Fern,100%cov) s(Fern,50%cov) s(Fern,25%cov)

1602002503154005006308001000125016002000250031504000

90

Figure79.ScatteringcoefficientofSpiderPlant,differentvegetationcoverage(25%,50%&100%)

0

0.2

0.4

0.6

0.8

1

120 1200



s(SpiderP,100%cov) s(SpiderP,50%cov) s(SpiderP,25%cov)

1602002503154005006308001000125016002000250031504000

91

6. DiscussionTheabsorptionofthelivingwallpanelinSabinewasdeterminedfirstfortheempty

carrierwhichareconstructedwithsignificantlydifferentmodules.Secondlyforthe

carrierswithsubstrate,thesubstrateevaluatedincludeda30/70mixtureofpumice

andpottingsoilanda20/80mixtureofthesame.Additionally,theeffectofthe

watercontentofthe30/70mixturewasevaluated.Finally,theabsorptionofthe

fullyvegetatedpanelwasevaluated.

Thematerialsandconstructionofthecarriersdonotdominatetheabsorption

performanceofthesystemoncethesubstrateisinstalled.Althoughthe2Dpanelsize

ofthecarrierAistwicetheareaofcarrierB.Thesubstratemassofthetwonon-

hydroponicsystemsarewithin10%ofeachother.Andthetwosystemperformed

similarlyinthemidfrequencyandwithin1Sabineinlowfrequencyand0.5Sabine

inhighfrequencies.Theresultsalsoshowtheincreaseinorganicmatterofthe

20/80ofpumiceandpottingsoilrelativetothe30/70didnotaffectabsorption.

6.1. AbsorptionoflivingwallpanelmeasurementTheabsorptionofthelivingwallpanelinSabinewasdeterminedfirstfortheempty

carrierwhichareconstructedwithsignificantlydifferentmodules.Secondlyforthe

carrierswithsubstrate,thesubstrateevaluatedincludeda30/70mixtureofpumice

andpottingsoilanda20/80mixtureofthesame.Additionally,theeffectofthe

watercontentofthe30/70mixturewasevaluated.Finally,theabsorptionofthe

fullyvegetatedpanelwasevaluated.

Thematerialsandconstructionofthecarriersdonotdominatetheabsorption

performanceofthesystemoncethesubstrateisinstalled.Althoughthe2Dpanelsize

ofthecarrierAistwicetheareaofcarrierB.Thesubstratemassofthetwonon-

hydroponicsystemsarewithin10%ofeachother.Andthetwosystemperformed

similarlyinthemidfrequencyandwithin1Sabineinlowfrequencyand0.5Sabine

92

inhighfrequencies.Theresultsalsoshowtheincreaseinorganicmatterofthe

20/80ofpumiceandpottingsoilrelativetothe30/70didnotaffectabsorption.

6.1.1. Effectofmoisturecontentandvegetationonthecarries’absorption AccordingtoFigure41,theabsorption(Sabine)oftheemptyCarrierA,madefrom

ABSplastic,islowest,CarrierB,madefromstainlesssteel,ismoreabsorptiveand

CarrierC,madeofinsulationmaterial,itexhibitssignificantlyhigherabsorption.8

Resultsindicatedthatusingamixof70%pottingsoiland30%pumicethe

differenceinabsorption(Sabine)betweenthepanelswithdrysubstrateandthe

panelswithsubstrateinfieldcapacityintheexperimentisconsiderableintwo

substratebasedsystems.Inthehydroponicsystem,whichrequiresirrigationonthe

hour,absorptiondecreasesrelativetoitswetness,aligningwiththeadditionalofthe

plantstothecarriersandsubstrateagainaffectsabsorption.

Above400Hz,thesubstrateatfieldcapacityislessabsorptivethanthedry

substrate.Theresultofthisstudyiscomparablewiththeresultoftheprevious

experiment[11].

Yang’sinvestigationsoftheabsorptioncoefficientforavegetationsubstrateitwas

reportedthathighlyporoussubstratesmaintainahighabsorptionevenwithhigh

moisturecontent[11].

Theadditionoftheplantstothecarriersandsubstrateagainaffectsabsorption.At

midandhighfrequencies,theresultsuggeststhattheplantedpanel,carrierAandB

islessabsorptivethanthepanelthatisfilledwithsubstrateonly,measuredatfield

capacity.Also,thedifferencebetweenplantedpanelsandsubstrate-onlypanels

absorptionincreaseswithfrequency,especiallyafter1600HzforCarrierAand

8Carrier A: recyclable ABS plastic; Carrier B: stainless-steel; Carrier C: isolative rock wool material used as a substrate.

93

CarrierB.TheabsorptionofCarrierCisthesamefortheemptypanelandthe

plantedpanel.Thevegetationimprovesthelowfrequencyabsorptionofcarrier

howeveritinverselyinfluencesthemidandhighfrequencyabsorption.

Theeffectofplanttypeontheabsorptionofasinglepanelwasevaluatedoncarrier

C.Thesixplantspeciesandamixofspeciesaffectabsorptionsimilarlyinthelow

andmidfrequencies.Athigherfrequenciesabove1000Hzthevariancein

absorptionincreaseswithfrequency.

6.2. Absorptionandscatteringof1/3scalemodel;thespeciestypeeffectonabsorptionandscatteringcoefficientatdifferentcoveragedensity

Themeasurementresultsoftheabsorptionandscatteringcoefficientofthefoliage

componentsofsixlivingwallspecies,withvariouslevelsofvegetationcoverage,

showedthatgenerally,theabsorptionandscatteringcoefficientsincreasewith

increasingvegetationdensity.

PriorinvestigationsbyNavarroetal[38]showedagreatereffectofscatteringon

thereverberationtimeformaterialswithlowerabsorptioncoefficients.

TheresultsofstudybyHurberandBednarsuggestedthatthelowscattering

coefficientsproducehighreverberationtimesinthesimulation.Reverberationtime

isincreasedwhentheabsorptioncoefficientisnotuniform[35].

Followingisacomparisonoftheeffectofplantspeciesandpercentagecoverageof

theplantsontheabsorptionandscatteringpropertiesofvegetation.

94

Table7illustratestheabsorptioncoefficientof6differentplantspeciesforeach

vegetationcoverage.Table7showsthattheabsorptioncoefficienttrendsof

differentspeciesaremoresimilarasthecoveragedensityincrease.

Table7.Absorptioncoefficientofallspecieswith100%,50%&25%vegetationcoverage(Frequenciesbetween(1000-4000Hz)

0

0.25

0.5

0.75

1

1000

AbsorptionCoefficient


6Species(100%cov)

α(Ivy100%cov) α(GoldenPothos100%cov)

αs(Pilea100%cov)

αs(CreepingFig100%cov)

αs(Fern100%cov)

αs(SpiderPlant100%cov)

α(Substrate70%/30%)

1000125016002000250031504000

0

0.25

0.5

0.75

1

1000



6Species(50%cov)

α(Ivy50%cov)

αs(GoldenPothos50%cov)

αs(Pilea50%cov)

αs(CreepingFig50%cov)

αs(Fern50%cov)


10001250160020002500 3150

0

0.25

0.5

0.75

1

1000



6Species(25%cov)

αs(Ivy25%cov)

αs(GoldenPothos25%cov)

αs(Pilea25%cov)

αs(CreepingFig25%)

αs(Fern25%cov)


αsSubstrate70%/30%

1000125016002000250031504000

95

Withtheleastvegetationcoverage(25%),thedifferencebetweenspeciesonsound

absorptionismorepronounced. At50%coverageitisclearthatatfrequencies

above1000Hz,thetrendsaremoresimilar.At1600Hzfrequencyallspecieswith

50%coveragehaveaboutthesameabsorption.Atfrequencieshigherthan1600and

with50%vegetationcoverage,SpiderPlantisthemostabsorptiveandPilea,

CreepingFig,Fern,GoldenPothosandIvyarethenextabsorptiveonesrespectively.

At100%coverage,thetypeofspeciesissignificantonlyathighfrequencies.

Between1000Hzand2000Hz,thetypeoftheplantdoesnotmakeanydifferencein

termsofabsorption.Theresultsalsoindicatethattheplantpropertiesaremore

significanthigherfrequenciesthevarianceinabsorptionincreaseswithincreasing

frequencybutisdimensionascoverageincrease.(Table7)

Table8belowshowstheabsorptioncoefficientresultbetween200Hzand2500Hz.

ASoundAbsorptionAverage(SAA)valueisasinglenumberratingthatindicatesthe

levelofsoundabsorptionprovidedbytheproductbeingtested[28].

TheSAAvalueistheaverageofthesoundabsorptioncoefficientsattwelve1/3-

octavefrequenciesrangingfrom200to2500Hertz.TheresultsshowninTable8

indicatethatat100%coverage,differentspeciesbehavedifferentlyintermsof

absorptivityatdifferentfrequencies.

96

Table8.Absorptionvaluefor6plantspeciesplantedontheturningtableatthreedifferentcoveragepercentages

Species 200 250 315 400 500 630 8001000

1250

1600

2000

2500 SAA

NRC

GoldenPothos25%cov 0.24 0.26 0.17 0.22 0.29 0.33 0.41 0.34 0.37 0.37 0.36 0.39 0.31

0.3


0.31


0.36

Ivy25%cov 0.08 0.13 0.19 0.17 0.21 0.18 0.31 0.33 0.30 0.33 0.33 0.41 0.250.25

Ivy50%cov 0.09 0.16 0.26 0.16 0.25 0.20 0.32 0.29 0.31 0.36 0.37 0.45 0.270.27

Ivy100%cov 0.18 0.29 0.37 0.27 0.31 0.28 0.37 0.35 0.38 0.41 0.43 0.45 0.340.34

Pilea25%cov 0.28 0.36 0.26 0.11 0.21 0.45 0.42 0.38 0.39 0.41 0.33 0.45 0.34

0.32

Pilea50%cov 0.14 0.18 0.48 0.24 0.23 0.38 0.40 0.40 0.40 0.40 0.40 0.47 0.340.34

Pilea100%cov 0.20 0.26 0.52 0.41 0.46 0.36 0.44 0.41 0.39 0.40 0.44 0.49 0.400.40

CreepingFig25% 0.15 0.13 0.18 0.23 0.33 0.29 0.38 0.34 0.37 0.39 0.40 0.43 0.30

0.30

CreepingFig50%cov 0.19 0.29 0.12 0.32 0.29 0.24 0.48 0.40 0.38 0.37 0.34 0.42 0.32

0.32

CreepingFig100%cov 0.26 0.14 0.10 0.33 0.33 0.33 0.48 0.40 0.35 0.38 0.44 0.49 0.34

0.33

SpiderPlant25%cov 0.51 0.53 0.37 0.43 0.51 0.45 0.58 0.50 0.44 0.45 0.44 0.56 0.48

0.40

SpiderPlant50%cov 0.29 0.53 0.09 0.32 0.30 0.42 0.43 0.44 0.41 0.37 0.41 0.50 0.38

0.37

SpiderPlant100%cov 0.00 0.17 0.00 0.36 0.43 0.23 0.43 0.37 0.41 0.44 0.38 0.53 0.31

0.31

Fern25%cov 0.08 0.06 0.09 0.09 0.11 0.12 0.12 0.11 0.12 0.14 0.14 0.17 0.11

0.1

Fern50%cov 0.30 0.22 0.00 0.19 0.42 0.33 0.42 0.33 0.33 0.36 0.33 0.43 0.31

0.3

Fern100%cov 0.25 0.21 0.00 0.18 0.35 0.48 0.44 0.39 0.35 0.40 0.42 0.50 0.33

0.33

97

Averagingtheabsorptionfromthesixplantspeciesatdifferentlevelofcoverageitis

illustratedthat,ingeneral,theabsorptioncoefficientincreaseswithincreasingthe

plantspeciesdensityofcoverage(Figure80).

Figure80.Averageabsorptioncoefficientof6differentspecieswith3differentvegetationcoverage,Emptyroom

andturningtableintheroom

0

0.5

1

1.5

80 800



α(Substrate70%/30%) α(AveragePlantSpecies100%cov)

α(AveragePlantSpecies50%cov) α(AveragePlantSpecies25%cov)

α(Turningtableintheroom) α(EmptyRoom)

1602002504005006308001000125016002000250031504000

98

6.2.1. ScatteringTheimpactofplantcoverageonsoundscatteringwasinvestigatedforeach

vegetationspecies.Asexpectedtheoveralltrendissimilartoabsorption,scattering

increaseswithfrequency.However,thevarianceinscatteringbetweentheplant

speciesincreasewithincreasingcoverage.Table10comparesthescattering

coefficientof6differentplantspeciesatthesamevegetationcoveragefor

frequenciesbetween1000Hzand4000Hz.

Table9illustratestheNRC(Scattering)ofsixspeciesunderstudyat25%,50%and

100%coveragerespectively.

AccordingtoTable10itisclearthatat100%coverage,SpiderPlant,CreepingFig,

FernandGoldenPothosscattermoresoundenergyatmidfrequencies(between

1000and2500Hz)withtheaveragesoundscatteringof0.24,0.19,0.187and0.14

respectivelyincomparisonwithIvyandPileawith0.5and0.4soundscattering

averagerespectively.

Table10showsthatthescatteringcoefficientresultsfor6specieswithadensityof

50%coveragefollowsasimilartrendto100%coverage.Soundscatteringaverage

forSpiderPlant,GoldenPothos,CreepingFig,Fern,PileaandIvyis0.15,0.13,0.11,

0,06,0.04and0.01respectivelyatfrequenciesbetween1000Hzand2500Hz.With

evenlessvegetationcoverage(25%),thedifferencebetweenspeciessound

scatteringismorepronounced.

99

Table9.NRC(Scattering)ofdifferentspeciesat25%,50%and100%coverage

NRC(Scattering)

Golden

Pothos

Ivy

Pilea

Creeping

Fig

Fern

Spider

Plant

25%cov 0.07 0.002 0.008 0.18 0.09 0.19

50%cov 0.17 0.02 0.13 0.07 0.18

100%cov 0.16 0.05 0.05 0.26 0.2 0.26

Table10.Scatteringcoefficientof6differentspecies,100%,50%&25%vegetationcoverage

0

0.2

0.4

0.6

0.8

1

820



6PlantSpecies(100%cov)

s(Ivy100%cov)

s(GoldenPothos,100%cov)

s(Pilea,100%cov)

s(CreepingFig,100%cov)

s(Fern,100%cov)

s(SpiderP,100%cov)

sSubstrate30%-70%

10001250160020002500315040000

0.2

0.4

0.6

0.8

1

820




s(Ivy50%cov)

s(Goldenpothos50%cov)

s(Pilea,50%cov)


s(Fern,50%cov)

s(SpiderP,50%cov)

1000125016002000250031504000

0

0.2

0.4

0.6

0.8

1

820




s(Ivy25%cov)

s(Goldenpothos25%cov)

s(Pilea,25%cov)


s(Fern,25%cov)

s(SpiderP,25%cov)

1000125016002000250031504000

100

Figure81illustratesthatscatteringcoefficient(averagedbetweenallspecies)

increaseswithvegetationcoverageabove500Hz.Itcanbeconcludedthatthe

vegetationdensity,evaluatedascoveragepercentageisimportantinincreasingthe

scatteringcoefficient.

Figure81.Averagescatteringcoefficientof6differentspecieswith3differentvegetationcoverage,andturningtableintheroom

0

0.2

0.4

0.6

0.8

1

120 1200


One-thirdOctaveBandsFrequency(Hz

s(AveragePlantSpecies100%cov) s(AveragePlantSpecies50%cov)

s(AveragePlantSpecies25%cov) sbase

------ssubstrateonturningtable

101

6.2.2. Therelationshipbetweentheabsorption&scatteringcoefficientandthepropertiesofsixavailablespecies

Absorptionandscatteringandplantpropertiesmeasurementswerecompletedon

plantspeciesat1/3-scale.Fromthemeasurements,itwasinvestigatedhow

significantlyplantcharacteristics(section5.3)canaffectabsorptionandscattering

coefficients.

Therelationshipbetweentheacousticalcharacteristicsofabsorptionand

scattering)andthepropertiesofthesixplantspecieswasexaminedusingsimple

scatteringplotstoidentifypossiblecorrelations.

Therelationshipsbetweentheabsorptioncoefficientsandscatteringcoefficientsto

propertiesoftheplantsarepresentedinAppendix6. Theplantscharacteristics

Height,leafthickness,stemdiameter,leaflength,drymass,wetmassandleafarea

areindependentvariables.Additionally,compoundedvariableswereexamined

including;LeafNumber*LeafArea,LeafNumber*LeafArea*LeafThickness,Leaf

Number*LeafArea*StemDiameter,LeafNumber*LeafArea*StemDiameter*

Height,LeafNumber*LeafArea*WetMass,LeafNumber*LeafArea*DryMass.

RecallthatLeafNumber*LeafAreaisthetotalleafareawhichisnotequaltoLAI.

Ingeneral,thecorrelationsuggeststhat,LAI*Mass(dryandwet)predictsscattering

coefficientsatmid-frequencies(200-2500Hz)andabsorptioncoefficientathigh

frequencies(2500-5000).

Thereisaweakindicationthattotalleafareaandmassintherangeof200and2500

Hzhaveanimpactontheabsorptioncoefficientofthevegetation(Appendix6-Table

A).Athighfrequency,thecorrelateoftotalleafareaandabsorptionisslightly

stronger(Appendix6-TableB).Atthespecificfrequencyof1333Hz(Appendix6-

TableC),thereisclearerindicationofrelationbetweenabsorptioncoefficientand

102

totalleafareaandwiththecompoundvariablesofLN*LAMassandalsoLN*LA*

Leafthickness.Thoseappearstronglyrelatedtoscatteringat1333Hzthough

(Appendix6-TableE).

Withrespecttothecorrelationofplantproperties,totalleafarea*massmayrelate

totheaveragescatteringcoefficient(Appendix6-TableD-F). Thereisaweak

indication,whichasksforfurtherinvestigation.

Inordertohaveresultsfrommultipleregressionsmodelling,moresamplesare

required.Thisisafurtherexplorationofthestudyby Attenborough[3],thatfound

theabsorptionbyleavestobeimportantathighfrequenciesabove1kHz,whereas

below1kHzthereislittlesoundabsorptionbyleaves.

103

6.3. Solvingfortheacousticalcoefficient

Livingwallpanelsareusuallyusedinacombinationofgeometricarrangementsand

becausethereisadiversityofapplicationofLivingWallSystems,itisdesirableto

haveanabsorptioncoefficientforpredictivemodelling.Thereforeconvertingthe

measuredSabinetoanabsorptioncoefficientvalueisrequired.

ResultindicatesthatforbothCarrierAandCarrierBtheabsorption(Sabine)does

notincreaselinearlywiththenumberofpanels(Figure59).Thepanelsareina3-

dimensionalshapewithcomplexsurfaces.Theunusualshapeofthepanelsandthe

factthattheeffectiveareachangeswithanassemblyofmultiplepanelsmustbe

takenintoaccount. Twomethodswereattemptedtoderivetheabsorption

coefficientofthelivingwallsystems.Thefirstmethodcalculatestheabsorption

coefficientbydividingtheareaofthetestspecimenintothemeasuredSabine

(Equation7).

Thesecondmethodinvolveddevelopingfrequencydependentlinearregression

equationstoresolvethecoefficient.

Itwasconsideredthattheacousticaleffectivearea,maybedifferentfromthe

architecturalareaofthelivingwallunitandthattheacousticaleffectiveareacould

bedetermined.

104

6.3.1. Attemptedmethodone

Theratioofabsorption(Sabine)overareashouldbethesameregardlessofthe

numberofpanels.However,usingarchitecturalarea(definedas2Darea)ofthe

panelsintheratioresultedinamismatchbetween3and1CarrierAasshownin

Figure82.Toaddressthisproblem,aneffectiveacousticalareawasderived.

Thefirstapproachsimplysummedthetotalexposedsurfaceareasofthepanelsina

livingwallgeometricconfiguration.

Figure82.measuredabsorptioncoefficientof1CarrierA

0

0.5

1

1.5

2

177 1770

AbsorptionCoefficientofMG


1MGpannel 3MGPannelsαfrom1CarrierA αfrom3CarrierA

105

SimplegeometricalapproachTheeffectiveacousticalarea(Equation10)formultiplepanels(1,2,3,…,n)each

livingwallsystemis:

EffectiveArea=n1(ab)+n2(bc)+n3(ca)Equation11

Wheren=numberofexposedsurfacesofageometricandconfiguration

Anda,b,c=thedimensionofthepanel

Usingthissimplegeometricapproachtodidnotresultinaconsistentabsorption

coefficient.

Complexgeometricapproach

Thesecondapproachusedcomplexgeometrytodescribethecarrierandleafarea

indextodescribetheexposesurfacesoftheplantsanddrivetheacousticaleffective

area.Thisareaiscalculatedbymeasuringthesidesandthemainareaofthepanel.

ThesubstrateandleafareasarebothestimatedusingtheLeafAreaIndex(LAI)of

40potsforeverypanel.Butevenwiththiscalculation,theacousticaleffectivearea

didnotresultinaconsistentabsorptioncoefficient(Sabineoverarearatio)for3

and1CarrierApanels.

Neithergeometricalapproachprovidesvalidmethodtoderivetheabsorption

coefficientoverthefrequencyspectrum(125Hzto4000Hz).Furtheraccordingto

a

b

c

Figure83.Samplebox

106

Figure58and59(section5.2.3),theratiobetweentheabsorptionofdifferent

numberofcarriersvarieswithfrequency.Thissuggeststhattheeffectiveacoustical

areaisfrequency-dependent.

6.3.2. Resolvingequation

Thegoalhereistoderivetotalabsorptionforaspecificnumberofpanels.Figure84

illustratestheplottedaverageSabineabsorption(rangefrom200to25001/3

octavedata)fromallthreetypesoflivingwallsystem.Usingalinearapproximation,

Equation12,canbederivedforcalculatingfortheaverageSABINEpanel.The

numberofpanelsusedintotaltherewere15measurementofasinglepanel,6

measurementsofthreepanels,3measurementsoffourpanelsand3measurement

ofeightpanels.RepeatingthesameprocedureforNRCrange(one-octaveband250

and2000HzleadstofindingEquations14-19.

Figure84.relationshipbetweentheaverageSabineandquantityofpanels

*TheR2=0.95792indicatesthatthelinearregressionmodelhasahighleveloffit

withthemeasureddata.Althoughthereisalimitedstatisticalpowerduetothe

numberofsamples.

y=0.4369x+0.6748R²=0.95792

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 1 2 3 4 5 6 7 8 9

AverageSAAofallsystems

NumberofPanels

Series1 Linear(Series1)measuredabsorption bestfit

107

Sabine(200-2500Hz)=0.4369N+0.6748Equation12

Sabine(200-2500Hz)=0.4577N+0.7167Equation13.

N=Numberofpanels

However,theabsorptionofthepanelsarefrequency-dependent.Therefore,using

thesamemethodsmentionedabove(Figure86),thefollowingequationswere

derivedforeachfrequency.

Theseequationsarebasedonpanelsizebetween0.36and0.72whereNisnumber

ofpanel.

Sabine125=(0.1054N+0.1435)Equation14.






Equation14to19wereusedfortheroomsensitivityanalysis(section6.4)

108

6.3.3. ScatteringcoefficientforapplicationinOdeonSurfacescatteringfunctionsusedinOdeonarederivedfromRindaltheory. InOdeon

thescatteringcoefficientforthemiddlefrequencyof707Hz,isrequiredasaninput

forthematerialslist,Odeonexpandsthiscoefficientintovaluesforeachoctave-

band[43].

Inordertofindthe707Hzscatteringcoefficientvalueforeachspeciesthe

scatteringcoefficientresultsfromlabmeasurementforeachspecieswasplottedina

graphalongwiththevaluesgeneratedbyRindalalgorithm(figure87).

Odeonresultsvs.labmeasurementsScatteringcoefficientof6differentspeciesismeasuredatdifferentfrequenciesas

showninFigure85.

Figure85.ScatteringcoefficientofsixspeciesresultsfromLabmeasurements

Figure86belowillustratestheaveragescatteringcoefficientofthesamespecies

excludingtheCreepingFig.Theaveragescatteringcoefficientis0.11forthemiddle

frequencyof707Hz(averageof500-1000Hz).AsOdeon,thecoefficientis

0.0

0.2

0.4

0.6

0.8

1.0

120 1200


Frequency(Hz)s(Ivy100%cov) s(GoldenPothos,100%cov)

s(Pilea,100%cov) s(CreepingFig,100%cov)

s(Fern,100%cov) s(SpiderP,100%cov)

2002505001000 2000

109

expandedintoscatteringcoefficientsvaluesforeachoctaveband–byinterpolation

orextrapolation.Thegraphlabeled0.11inFigure87bshowstheresult.

Figure86.ScatteringresultsfromLabmeasurements&Odeonsuggestedscatteringcoefficients(FrequencyfunctionsforPlantsat707Hz)[43])

Comparingtheaveragescatteringcoefficientfromthelabmeasurementswith

Odeonsoftware’sexpandedscatteringcoefficients,itwasdeterminedthatgraphs

alignwellinthemidandhighfrequencies.Althoughthelabresultssuggestssome

morescatteringinthelowandhighfrequenciesthantheOdeonmodel.

0

0.2

0.4

0.6

0.8

1

125 1250


Frequency(Hz)

0.11 Labresult

707 1000

Odeon

110

6.4. RoomsensitivityanalysisOdeonwasusedtoestimatethereverberationtimeofa56m2roomsizespace,with

andwithoutthelivingwalls.Theeffectofdifferentconfigurationsoflivingwall

systemsintheroomweremodeled.Inaddition,thesensitivityofusingthe

empiricallymeasuredscatteringcoefficientvaluetothelivingwallsurfaceswas

analyzed.

6.4.1. RoomdefinitionThecasestudycouldbeatypicalofficeorsmallclassroomsizespace.Theroom

dimensionsweresetat7.5m*7.5mandheight3.5withthebasedrywallcondition

developedwasonallwallsurfacesandconcreteforthefloorandceilingsurfaces.

Thepointsourcewaslocatedinthemiddleoftheroomat1-meterheight.One

sourceintheroomandfive-receiverlocationswererandomlylocated.

First,thebaseconditionwasmodeled.Second,theroomwasmodeledwithonewall

coveredwithlivingwallsystems(211-m2panels).Third,theroomwasmodeled

with2wallscoveredwithlivingwallsystemsparallelandperpendiculartocheck

theeffectofdifferentconfigurationsoflivingwalls.Finally,thecasestudywasalso

modeledwithall4wallscoveredwiththelivingwallsystem.Themodelswere

repeatedwithandwithoutconsideringscatteringcoefficient.TheOdeonmodel

defaultforscatteringwasnotused.Thescenariosmodeledincludedscattering

coefficientof0forallsurfaces,scatteringcoefficientof0forwall,floor,andceiling

surfaces,andscatteringcoefficientvaluederivedfromlabdataforlivingwalls

surfaces.

ForthefirstseriesofOdeonmodels,theassignedabsorptionwasderivedfrom

equations13to18.TheassignedscatteringcoefficientwastakenfromSection5.3.3.

Forthesecondseries,bothabsorptionandscatteringcoefficientofthelivingwall

surfacesweretakenfrom1/3-scalemeasurementsonaturningtable(Section5.3).

111

(a) Oneside

(b)Parallel

(c)Perpendicular

(d)Allsides

Figure87.Livingwallsdifferentconfigurationsinroom.

112

6.4.2. Modeltheroomeffectoflivingwalls

ThevegetatedlivingwallsystemsintheroomweremodeledinOdeonusingabsorptionvaluesandscatteringcoefficientfoundfromlabmeasurements(5.3.3)

Figures88,89and90illustratethatthedifferencebetweentheresultof

reverberationtimelivingwallswithandwithoutthescatteringcoefficient,ismore

dramaticfortheroomwith1livingwall,21panelwith2livingwalls,42panelsor4

livingwalls,84panels.

AsseeninFigure88,Odeonresultshowsthesignificantdifferenceinreverberation

timebetweenthemodelthatincludesthescatteringcoefficientofthelivingwall

areaandthemodelwithscatteringcoefficientsetto0forallsurfaces.Reverberation

timevaluesincreasebyabout0.25throughallfrequencieswhenscatteringis

considered.Thisemphasizestheimportanceofconsideringthescatteringcoefficient

whenusingOdeonsoftwaremodellingfortheacousticalevaluationofthespace.

Figure90illustratesthatwhenallthefourwallsoftheroomarecoveredwithliving

walls,applyingthescatteringcoefficienttothelivingwallssurfacesdoesnotmakea

significantdifferenceintermsofreverberationtimeintheroom.

113

Figure88.Reverberationtimeoftheroomwithlivingwallononeside;sc=0vs.scvalue

Figure89.Reverberationtimeoftheroomwithlivingwallsontwosides;sc=0vs.scvalue

0

0.5

1

1.5

2

2.5

125 1125 2125 3125 4125 5125 6125 7125

ReverbrationTime(T20)


EmptyRoom 1MGLWinroom(NoS) 1MGLWinroom(S)

010002000300040005000600070008000

1LWinroom(S) 1LWinroom(NoS)

0

0.5

1

1.5

2

2.5

125 1125 2125 3125 4125 5125 6125 7125

ReverberationTime(T20)


EmptyRoom 2perpendicularMGLWsinroom(Nos)

2perpendicularMGLWsinroom(s) 2parallelMGLWsinroom(Nos)

2parallelMGLWsinroom(s)

010002000300040005000600070008000

2PerpendicularLWsinroom(NoS)

2ParallelLWsinroom(NoS)

2PerpendicularLWsinroom(S)

2ParallelLWsinroom(S)

115

wallsreducesreverberationtimebyabout0.3atlowfrequenciesand0.2at

frequenciesafter4000Hz. Thegraphshowsthat,ingeneral,increasingthenumber

oflivingwallsdecreasethereverberationtimeoftheroomandkeepingthewalls

perpendicularismoreefficientthanhavingtheminparallel.Thesemodelisinclude

theabsorptionvaluesderivedfromequation12-19andtolabmeasuredscattering

coefficient.

Figure91.Reverberationtimeoftheroomwithdifferentconfigurations(Emptyroomisbaseline)

Figure92showsreverberationtimeofplantspecieswithtwodifferentabsorption

coefficients.TheOdeonmodelisimplementedforspeciesonturningtableandthe

onesonlivingwallpanels.

Thegraphslabeled“S”showstheresultofreverberationtimewithscattering

coefficientappliedtothelivingwalls.Reverberationtimeincreasesbyapplying

scatteringcoefficientinbothcases.

0

0.5

1

1.5

2

2.5

0 1000 2000 3000 4000 5000 6000 7000 8000


One-thiredOctaveBandsFrequency(Hz)-Series1

EmptyRoom 1MGLWinroom(S)

2perpendicularMGLWsinroom(s) 2parallelMGLWsinroom(s)

4MGLWsinroom(s)

1LWinroom(S)

2ParallelLWsinroom(S)

Emptyroom

2PerpendicularLWsinroom(S)

4LWsinroom(S)

116

Figure92.Reverberationoftheroomwithdifferentabsorptioncoefficientvaluesforlivingwalls.

0

0.5

1

1.5

2

2.5

0 1000 2000 3000 4000 5000 6000 7000 8000 9000



1EGLWinroom(NoS) 1EGLWinroom(S)

1MGLWinroom(S) 1MGLWinroom(NoS)

1LW(S)series2 1LW(NoS)serries2

1LW(NoS)serries1 1LW(S)serries1

117

7. CONCLUSIONSANDOUTCOMESInthisinterdisciplinaryresearchthebasisofthedataanalysiswastofindoptimal

carrierpropertiesforefficientsoundabsorptionininteriorlivingwalls.

Experimentaldataforsoundabsorptionpropertiesofmaterialsisanessentialtool

fornoisecontrolspecialists.Inthisresearch,acousticalcharacterizationsofinterior

livingwallsaremeasured.Theevaluationgoalistoquantifytheimpactofthe

interiorlivingwallsonindooracousticalquality.Aseriesofmeasurementswere

carriedoutinareverberationchambertoexaminerandom-incidenceabsorption

coefficientsoffulllivingwallsystem,alsorandom-incidenceabsorptionand

scatteringcoefficientofavarietyofvegetation,consideringvariousfactorssuchas

vegetationtypesandvegetationcoverage.Thefinalstepwasmodellingthecase

studybyusingthedatafromthelabmeasurementstoinvestigatethemodel

sensitivitytothedata.

Twomethodswereestablishedforobtainingdataontheacousticalcharacteristicof

livingwallsinreverberationchamber.Firstoneistheabsorptionmeasurementof

livingwallsystematfullscaleandsecondoneisthe1/3scaleabsorptionand

scatteringmeasurementsoflivingwallplantspecies.

Whencomparingabsorption(Sabine)ofempty,vegetatedandcarriersfilledwith

substratetooneanother,itisclearthattheabsorptionofalllivingwallpanelshave

thesametrendwithvariationinabsorptionduetodifferentmaterialsandgeometry

ofthepanel.Addingsubstrateandplanttocarrierschangestheirrelative

performanceandforthesubstratebasesystemnegatesthedifferencesofpanel

construction.Theresearchconfirmedthatdriersubstratemixabsorbssignificantly

moresoundthanthesubstrateinfieldcapacity.Atmidandhighfrequencies,the

resultshowedthattheplantedpanelislessabsorptivethanthepanelthatisfilled

withsubstrate.Thevegetationimprovesthelowfrequencyabsorptionhoweverit

inverselyinfluencesthemidandhighfrequencyabsorption.

118

Theimpactofthethreedifferentlevelsofplantcoverageinsoundabsorptionand

soundscatteringwasinvestigatedforeachplantspecies.Fromtheresultsitcanbe

concludedthattheabsorptioncoefficientandscatteringcoefficientincreaseswith

increasingtheplantspeciesdensityofcoverage.Withlessvegetationcoverage,the

differencebetweenspeciessoundscatteringismorepronounced.Whilethe

absorptioncoefficienttrendsofdifferentspeciesaremoresimilarasthecoverage

densitydecreases

Inthisstudytherelationshipbetweentheabsorptioncoefficientandscattering

coefficientandthepropertiesoftheplantswaspresented.

Thereisanindicationthatatmidfrequenciestotalleafareaandmasshavean

impactontheabsorptioncoefficientofthevegetation.Itcanbeconcludedthat

LAI*Mass(dryandwet)predictsscatteringcoefficientsatmid-frequencies(200-

2500Hz)andabsorptioncoefficientathighfrequencies(2500-5000).

TwoseriesofOdeonmodelswithconsideringdifferentmethodofassigning

absorptionandscatteringvaluesforlivingwallsurfaceswasusedtoestimatethe

reverberationtimeofaroom,withandwithoutthelivingwalls.Theresultusing

datafromthemeasurementoffullyestablish,ratherthanplantspeciesdataismost

plausible.Resultsshowthatvegetationdecreasesthereverberationtimeand

increasingthenumberoflivingwallsdecreasethereverberationtimeofthe

modeledroom.Resultsalsoillustratetheimportanceofconsideringthescattering

coefficientwhenusingOdeonsoftwaremodellingandscatteringcoefficientdatais

moreessentialforsmallerlivingwallinstallations.Alsodifferentconfigurationsof

livingwallsystemsweremodeled.

Somedifferenceswithpreviousstudieswerefoundintermsofthesoundabsorption

coefficient,mostlikelyduetothedifferencesinthetestedconstructive.However,

despitethesedifferences,thepotentialofthegreenwallsoundabsorptiontoolfor

buildingscanbeconfirmed.Itcouldbeconcludedthatgreenwallscanbeusedasa

soundabsorptivematerialsinsidethebuildings.Wealsoconcludedthattheeffectof

119

thetypeoftheplantonabsorptionandscatteringofthelivingwallsisnotnoticeable

inpractice.

Thepracticalconsiderationfordesignersofsoil-basedlivingwallsystemsisthatthe

primarydeterminingfactorsinabsorptionandscatteringistheamountofsoiland

plantcoverageforagivenlivingwallsystem’ssurfacearea.Thisistrueevenwhen

emptycarriershavedifferentabsorptionandscatteringcharacteristic.Itshouldalso

benotedthattypeoftheplantspecieshaslimitedimpactonabsorptionand

scatteringofthelivingwallsystem.

Themaincontributionofthisresearchistocharacterizeandintroduceinterior

livingwallsasasustainableandacousticallybeneficialmaterialtothedesignerteam

andtoprovidethedesignerswithpracticalmeanstoevaluateaninstallationofthe

livingwallsystems.Absorptionandscatteringcoefficientsarenowavailablefor

roomprediction.

8. FUTUREWORKThisinterdisciplinaryresearchgoalistolookatthepotentialoftheinteriorliving

wallandenablemoresophisticatedandmatureuseofit.Theresultsofthese

evaluationsprovideuswithenoughinformationtoexplaintheacousticalbenefitsof

usinginteriorlivingwalls.Eventually,withanunderstandingofallthementioned

factorsandparameters,theefficiencyoflivingwallscanbeoptimizedtoimprove

theacousticalenvironmentofaroom.

Todeterminetheexactinfluenceofthescatteringcoefficientonthereverberation

time,furtherstatisticalanalysisisnecessary.Todeterminethevalidityofthe

measureddataacrossexaminationofroompredictionmodellingandfield

measurementsarerequired.

120

GLOSSARYANDABBREVIATIONSAbsorption coefficient:A value that shows how efficient a material absorbs

incidentsound.

Diffuse sound field: Sound field in which the incident sound intensity on a plane

surfaceisequallydistributedoverallsolidanglescoveringahemisphere[17].

Hydroponic:Thetechnologyofgrowingplantswithoutsoil.

Interruptednoisemethod:Methodofobtainingdecaycurvesbydirectrecording

of the decay of the sound pressure level after exciting a room withbroadband or

band-limitednoise[18].

Integrated impulse response method:Method of obtaining decay curves by

reverse-timeintegrationofthesquaredimpulseresponse[18].

Impulseresponse:Temporalevolutionofthesoundpressureobservedatapoint

inaroomasaresultoftheemissionofaDiracimpulseatanotherpointintheroom

[18].

MoistureContent(MC):Theamountofwaterinamateriallikesoil[42].

NoiseReduction(NR): Noise level measured at source position minus noise level

measuredatreceiverposition.

NRCorNRCC:NationalResearchCouncilofCanada.

RealTimeAnalyzer(RTA):Instrumentformeasuringanacousticproperty.

121

ReverberationTime(RT):Thetimeittakesforsoundlevelstoattenuateby60dB

withinaspace,importantacousticallyforcalculationofroomsoundabsorption[41].

SAA:The SAA value is the average of the sound absorption coefficients at twelve

1/3-octavefrequenciesrangingfrom200to2500hertz.[62]

soundabsorptionaverage,SAA—asinglenumberrating,theaverage,roundedoffto

thenearest0.01,ofthesoundabsorptioncoefficientsofamaterialforthetwelve

one-thirdoctavebandsfrom200through2500Hz,inclusive,measuredaccordingto

thistestmethod.

SoundAttenuation:Decreaseinsoundlevel.

Soundpressurelevel(SPL):istheratiooftheabsolute,SoundPressureanda

referencelevelwhichisthethresholdofhearing.SPLispresentedinalogarithmic

valueofdecibels(dB)[41].

Specularreflection: reflection that obeys Snells law, i.e. the angle of reflection is

equaltotheangleofincidence[17].

Speech Transmission Index (STI): A value to evaluate the speech transmission

quality. Measuring some physical characteristics of a transmission channel, for

instance a room, telephone line, etc. can determine the effect of transmission

channelcharacteristicsonspeechintelligibility.

Speechintelligibility:Ameasuretopredicthowclearlyspeechcanbeunderstood

inaroom.(Vorland,Michael,Eckard)

Scattering:Thedifferencebetweenthetotalreflectedenergyandthespecular

reflectedenergy

122

AKNOWLEDGEMENTSSpecialthankstoDr.MaureenConnellyandtomyfellowgraduatestudentRosaLin

andIvanCheungandtothecommitteemembers,Dr.KarenBartlettandMichel

LabrieMAIBCandeveryonewhohashelpedmealongthewaytomakethisthesis

projectpossible.

123

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126

APPENDICES

Appendix1:Theconsideredacousticalstandardsandcriteriainthisresearch

Table11.Standards

Acoustical Measurement Standards

Primary Measurement Standards

- ANSI S12 :Measurement of sound

pressure(indoors)

Laboratory Measurement Standards

- ASTM C-423: Sound absorption of materials

Field Measurement Standards

- ANSI S12.2: Criteria for evaluating room

noise

- ASTM E-1574: Sound pressure level in

residential spaces

- ASTM E-1130: Speech privacy in open

offices

- ASTM E-336: Airborne sound attenuation in

buildings

Table12.Criteria

Noise Level Criteria

Lw, LwA Sound power levels of a source

dB, dBA, dBC Sound pressure levels at a receiver

NC Indoor noise criteria, in octave bands

RC Indoor room criteria, in octave bands

RC Mark II Indoor room criteria in octave bands

NCB Indoor balanced noise criteria, in octave bands

RNC Indoor room noise criterion, in octave bands

ISO226 One of available criteria for evaluating low frequency noise

127

Appendix2:IrrigationsystemTable13.Systemswaterflow(Irrigationsystem)

Wall(everythinginkg) Water(kg)in5min WaterFlow(Lit/Day) Litofwaterin1min

Modulogreen-All 2.604 3.1248 0.5208

Modulogreen-Topleft 0.942 1.1304 0.1884

Modulogreen-Bottomright 0.894 1.0728 0.1788

Plantconnection-Toprow 2.844 3.4128 0.5688

Plantconnection-Middlerow 3.047 3.6564 0.6094

Plantconnection-Bottomrow 2.195 2.634 0.439

Evergreen-All 2.748

Appendix3:1/3scaledturningtableparametersTable14.Parametersanddimensionsofturningtable[45]

Parameters & Dimension of Turntable

ISO 17497-1 Standard

1/3 scale model

Actual Represents Diameter of Turntable 3.0 m 1.2 m 3.75 m Area of Turntable 7.065 m2 1.23 m2 3.7 m2 Thickness of Turntable - 1.5 cm 4.5 cm Air gap below the table As small as possible 9 cm 27 cm Volume of chamber Min 197 m3 88.78 m3 2397.06 m3 Frequency Range 40-5000 Hz 53-2333 Hz 160-5000 Hz

Figure93.Sectionofturningtable

128

Appendix4:EquipmentandfacilitiesTheacousticchamberusedforabsorptionandscatteringevaluation.Theequipment

requiredincludes:

• Omni-directionalspeaker(mustbeimplementedtoachieveanexcited,uniform,

measuredspace.),

• RTA(realtimeanalyzer),

• Testsignalnoisegenerator,

• Powersupplyandpower,

• Pressuremicrophone,

• Computertoanalyzethedata,

• Scatteringtable

• Odeonsoftwaretobeusedforanalyses.

129

Appendix5:ThemeasurementconditionofCarrierA&B

(a)1Panel (b)3Panels

Figure94.Themeasurementconditionof(a)1Modulogreenpaneland(b)3ModulogreenPanels

3.56

4.46

S

0.50

0.50

1.06

0.79

3.56

4.46

S

0.50

0.50

2.14

0.79

0.73

1.06

1.03

1.221.14

12

3

130

1Panel 8Panels

Figure95.ThemeasurementconditionofMultipleplantconnectionpanels

3.56

4.46

S

0.50

0.50

0.60

0.51

1.06

2.11

1.11

3.56

4.46

S

0.50

0.50

1 2 3

4

7

5

8

6

1.90

1.901.06

1.25

1.37

131

Appendix6:TableA.SAASoundAbsorptionCoefficient(Averageof200to2500Hz)&PlantProperties

PlantProperties

LN:LeafNumberofplantsundermeasurementsonscatteringtable.LA:LeafArea(mm2).SD:StemDiameter

y=-0.0002x+0.3916R²=0.10685

0

0.5

130 180 230

SAA

(mm)

Height&SAA

0

0.5

1.2 1.7 2.2 2.7 3.2

(mm)

StemD&SAA

y=-0.0351x+0.357R²=0.12886

0

0.5

0.00 0.20 0.40 0.60 0.80

(mg)

Wetmass&SAA

0

0.5

0.00 0.02 0.04 0.06

SAA

(mg)

Drymass&SAA

y=0.0001x+0.332R²=0.1709

0

0.5

0 100 200

LN

LeafNo&SAA

y=-0.2758x+0.3658R²=0.32397

0

0.5

0 0.1 0.2

(m)

Leaflenght&SAA

y=0.1344x+0.2894R²=0.20258

0

0.5

0.3 0.4 0.5 0.6

SAA

(mm)

ThichnessofLeaf&SAA

y=4E-05x+0.332R²=0.1709

0

0.5

0 500

LAI

LAI&SAA

y=-0.0884x+0.3657R²=0.20991

0

0.5

0 0.2

(mm)2

Leafarea&SAA

y=-0.0055x+0.3951R²=0.48606

0

0.5

5 10 15

SAA

(mm)2

LeafNo*Leafarea&SAA

y=-0.008x+0.3807R²=0.29188

0

0.5

1.8 3.8 5.8 7.8

(mm)3

LN*LA*LeafThicnes&SAA

0

0.5

0 20 40 60

(mm)3

LN*LA*Stem&SAA

y=-3E-06x+0.3665R²=0.23656

0

0.5

0 5000 10000

SAA

(mm)4

LN*LA*Stem*Height&SAA

y=-0.0043x+0.3625R²=0.40152

0

0.5

0 5 10

(mm)2mg

LN*LA*Wetmass&SAA

y=-0.0527x+0.3676R²=0.40364

0

0.5

0 0.5 1

(mm)2mg

LN*LA*Drymass&SAA

132

TableB.SoundAbsorptionCoefficient,HighFrequencies,(Averageof2500to5000)&PlantProperties

PlantProperties

HF:SoundAbsorptionCoefficientAverageofHighfrequencies(2500-5000)

y=-0.0027x+2.253R²=0.19035

1

1.5

2

2.5

130 180 230

HF

(mm)

Height&HF

1

1.5

2

2.5

0 1 2 3 4

(mm)

StemD&HF

R²=0.16269

1

1.5

2

2.5

0 0.2 0.4 0.6 0.8

(mg)

Wetmass&HF

y=-2.8664x+1.8359R²=0.076

1

1.5

2

2.5

0 0.02 0.04 0.06 0.08

HF

(mg)

Drymass&HF

y=0.0009x+1.6435R²=0.10188

1

1.5

2

2.5

0 100 200 300

LN

leafNo&HF

y=-2.6049x+1.9186R²=0.38749

1

1.5

2

2.5

0 0.05 0.1 0.15 0.2

(m)

Leaflenght&HF

y=-0.2203x+1.8446R²=0.0073

1

1.5

2

2.5

0.3 0.4 0.5 0.6

HF

(mm)

Leafthickness&HF

y=0.0003x+1.6435R²=0.10188

1

1.5

2

2.5

0 200 400 600 800

LAI

LAI&HF

y=-0.8948x+1.93R²=0.28819

1

1.5

2

2.5

0 0.1 0.2 0.3 0.4

(mm)2

LeafArea&HF

y=-0.0377x+2.0927R²=0.33591

1

1.5

2

2.5

4 9 14

HF

(mm)2

LN*LA&HF

1

1.5

2

2.5

1 3 5 7

(mm)2

LN*LA*LeafThickness&HF

y=-0.0064x+1.9391R²=0.346

0

1

2

0 20 40 60

(mm)2

LN*LA*stemd&HF

y=-3E-05x+1.9328R²=0.3532

1

1.5

2

2.5

0 5000 10000 15000

HF

(mm)4

LN*LA*Stem*Height&HF

y=-0.0415x+1.8898R²=0.49971

1

1.5

2

2.5

0 13

(mm)2mg

LN*LA*Wetmass&HF

y=-0.5468x+1.9546R²=0.58348

1

1.5

2

2.5

0 0.2 0.4 0.6 0.8 1

(mm)2mg

LN*LA*Drymass&HF

133

TableC.SoundAbsorptionCoefficient(At1333Hz)&PlantProperties

PlantProperties

y=0.0017x+0.5625R²=0.27136

0

1

130 180 230

At1333Hz

(mm)

Height&1333Hz

0

1

0.5 1.5 2.5 3.5

(mm)

Stemdia&1333Hz

y=0.3307x+0.7931R²=0.55213

0

1

0 0.2 0.4 0.6 0.8

mg

Wetmass&1333Hz

y=3.1268x+0.7844R²=0.32634

0

1

0 0.02 0.04 0.06

At1333Hz

(mg)

Drymass&1333Hz

y=-0.0005x+0.939R²=0.11776

0

1

0 100 200

LN

leafN&1333Hz

y=1.8097x+0.7615R²=0.67496

0

1

0.01 0.06 0.11 0.16

(mm)

Leaflenght&1333Hz

y=0.1573x+0.811R²=0.01342

0

1

0.3 0.4 0.5 0.6

At1333Hz

(mm)

Leafthickness&1333Hz

y=-0.0002x+0.939R²=0.11776

0

1

0 200 400 600 800 1000

LAI

LAI&1333Hz

y=0.6026x+0.7574R²=0.47162

0

1

0 0.1 0.2 0.3

(mm2)

LeafArea&1333Hz

y=0.0313x+0.6214R²=0.72153

0

1

5 10 15

At1333Hz

(mm2)

LN*LA&1333Hz

y=0.0579x+0.6602R²=0.69134

0

1

1.8 3.8 5.8 7.8

(mm)3

LN*LA*LeafThickness&1333Hz

y=0.0027x+0.7835R²=0.32518

0

1

5 25 45

(mm)3

LN*LA*stemd&1333Hz

y=1E-05x+0.7858R²=0.33759

0

1

500 5500 10500

At1333Hz

(mm)4

LN*LA*Stem*Height& 1333Hz

y=0.0264x+0.7899R²=0.72821

0

1

0 5 10

(mm)2mg

LN*LA*Wetmass&1333Hz

y=0.3085x+0.7633R²=0.67024

0

1

0 0.2 0.4 0.6 0.8 1

(mm)2mg

LN*LA*Drymass&1333Hz

134

TableD.SoundScatteringCoefficient(Averageof200to2500Hz)&PlantProperties

PlantProperties

y=0.0008x-0.0045R²=0.17574

0.0

0.3

130 170 210 250

Avgs.c

(mm)

Height&Avgs.c

0.0

0.3

0 1 2 3 4

(mm)

Stemdia&Avgs.c

y=0.155x+0.0985R²=0.38327

0.0

0.3

0.0 0.2 0.4 0.6 0.8

(mg)

Wetmass&Avgs.c

y=1.3552x+0.0978R²=0.19366

0.0

0.3

0.00 0.05

Avgs.c

(mg)

Drymass&Avgs.c

0.0

0.3

0 100 200 300

LN

LeafNo&Avgs.c

y=0.8723x+0.0821R²=0.49545

0.0

0.3

0 0.05 0.1 0.15 0.2

(m)

Leaflenght&Avgs.c

0.0

0.3

0.00 0.50 1.00

Avgs.c

(mm)

Leafthichness&Avgs.c

0.0

0.3

0 200 400 600 800 1000

LAI

LAI&Avgs.c

y=0.296x+0.079R²=0.35954

0.0

0.3

0 0.1 0.2 0.3 0.4

(mm2)

Leafare&Avgs.c

y=0.0164x+0.0024R²=0.63319

0.0

0.3

4 9 14

Avgs.c

(mm)2

LeafNo.*Leafarea*Avgs.c

y=0.0282x+0.0307R²=0.52235

0.0

0.3

1.5 3.5 5.5 7.5 9.5

(mm)3

LN*LA*Leafthickness&Avgs.c

y=0.0016x+0.0878R²=0.25538

0.0

0.3

0 20 40 60

(mm)3

LN*LA*Stemdia&Avgs.c

y=8E-06x+0.0898R²=0.25114

0.0

0.3

0 5000 10000

Avgs.c

(mm)4

LN*LA*Stem*Height&Avgs.c

y=0.013x+0.0949R²=0.55784

0.0

0.3

0 5 10

(mm)2mg

LN*LA*Wetmass&Avgs.c

y=0.1534x+0.0813R²=0.5232

0.0

0.3

0 0.5 1

(mm)2mg

LN*LA*Drymass&Averages.c

135

TableE.SoundScatteringCoefficient,HighFrequencies,(Averageof2500to5000)&PlantProperties

PlantProperties

y=-0.0023x+0.9058R²=0.16364

0.0

1.0

130 180 230

s.cHF

(mm)

Height&Avgs.cHF

0.0

1.0

0 1 2 3 4

(mm)

Stemdia&Avgs.cHF

0.0

1.0

0.0 0.2 0.4 0.6 0.8

(mg)

Wetmass&Avgs.cHF

0.0

1.0

0 0.05 0.1

s.cHF

(mg)

Drymass&Avgs.cHF

0.0

1.0

0 100 200 300

LN

LeafNo&Avgs.cHF

y=-0.9487x+0.5411R²=0.06176

0.0

1.0

0 0.05 0.1 0.15 0.2

(m)

Leaflenght&Avgs.cHF

0.0

1.0

0.3 0.5

s.cHF

(mg)

Leafthichness&Avgs.cHF

y=0.0002x+0.4031R²=0.06404

0.0

1.0

0 200 400 600 800

LAI

LAI&Avgs.cHF

y=-0.6176x+0.6043R²=0.16493

0.0

1.0

0 0.1 0.2 0.3 0.4

(mm)2

Leafare&Avgs.c

0.0

1.0

0 5 10 15 20

s.cHF

(mm)2

LeafNo.*Leafarea*Avgs.c

0.0

1.0

0 2 4 6 8

(mm)3

LN*LA*Leafthickness&Avgs.cHF

y=-0.0049x+0.5895R²=0.15723

0.0

1.0

0 20 40 60

(mm)3

LN*LA*Stemdia&Avgs.c

0.0

1.0

0 5000 10000

s.cHF

(mm)4

LN*LA*stem*Height&Avgs.cHF

y=-0.016x+0.5336R²=0.08929

0.0

1.0

0 5 10 15

(mm)2mg

LN*LA*Wetmass&Avgs.c

y=-0.2765x+0.5833R²=0.17915

0.0

1.0

0 0.5 1

(mm)2mg

LN*LA*Drymass&Avgs.c

The Absorption and Scattering Characteristics of Interior ...

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