Environmental Life-Cycle Assessment of an Innovative Multifunctional Toilet

Abstract

Innovative toilets can save resources, but have higher embodied impacts associated with materials and electronic components. This article presents an environmental life-cycle assessment (LCA) of an innovative multifunctional toilet (WashOne) for two alternative configurations (with or without washlet), comparing its performance with those of conventional systems (toilet and bidet). Additionally, two scenario analyses were conducted: (i) user behavior (alternative washlet use patterns) and (ii) user location (Portugal, Germany, the Netherlands, Sweden and Saudi Arabia). The results show that the WashOne with washlet has a better global environmental performance than the conventional system, even for low use. It also reveals that the use phase has the highest contribution to impacts due to electricity consumption. User location analysis further shows that Sweden has the lowest environmental impact, while Germany and the Netherlands have the highest potential for impact reduction when changing from a conventional system to the WashOne. Based on the overall results, some recommendations are provided to enhance the environmental performance of innovative toilet systems, namely the optimization of the washlet use patterns. This article highlights the importance of performing a LCA at an early stage of the development of innovative toilets by identifying the critical issues and hotspots to improve their design and performance.

Full text

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Energies2021,14,2307.https://doi.org/10.3390/en14082307www.mdpi.com/journal/energies
Article
EnvironmentalLife‐CycleAssessmentofanInnovative
MultifunctionalToilet
CarlaRodrigues
1,
*,JoãoAlmeida
2,3
,MariaInêsSantos
2
,AndreiaCosta
4
,SandraAlém
5
,EmanuelRufo
5
,
AntónioTadeu
2,6
andFaustoFreire
1
1
ADAI‐LAETA,DepartmentofMechanicalEngineering,FacultyofSciencesandTechnology,Universityof
Coimbra,RuaLuísReisSantos,PóloII,3030‐788Coimbra,Portugal;fausto.freire@dem.uc.pt
2
Itecons—InstituteforResearchandTechnologicalDevelopmentinConstruction,Energy,Environmentand
Sustainability,RuaPedroHispano,3030‐289Coimbra,Portugal;joao.almeida@itecons.uc.pt(J.A.);
mariaines.santos@itecons.uc.pt(M.I.S.);tadeu@dec.uc.pt(A.T.)
3
ChemistryCentre,DepartmentofChemistry,FacultyofSciencesandTechnology,UniversityofCoimbra,
RuaLarga,PóloI,3004‐535Coimbra,Portugal
4
OLI—SistemasSanitários,S.A.,TravessadoMilão,Esgueira3800‐314Aveiro,Portugal;
andreiac@oli‐world.com
5
Sanindusa—IndústriadeSanitáriosS.A.,ZonaIndustrialAveiroSul,RuaAugustoMarquesBranco,84,
3810‐783Aveiro,Portugal;sandraalem@sanindusa.pt(S.A.);emanuelrufo@sanindusa.pt(E.R.)
6
ADAI,DepartmentofCivilEngineering,FacultyofSciencesandTechnology,UniversityofCoimbra,
RuaLuísReisSantos,PóloII,3030‐788Coimbra,Portugal
*Correspondence:carla.rodrigues@dem.uc.pt;Tel.:+351‐239‐790708
Abstract:Innovativetoiletscansaveresources,buthavehigherembodiedimpactsassociatedwith
materialsandelectroniccomponents.Thisarticlepresentsanenvironmentallife‐cycleassessment
(LCA)ofaninnovativemultifunctionaltoilet(WashOne)fortwoalternativeconfigurations(withor
withoutwashlet),comparingitsperformancewiththoseofconventionalsystems(toiletandbidet).
Additionally,twoscenarioanalyseswereconducted:(i)userbehavior(alternativewashletuse
patterns)and(ii)userlocation(Portugal,Germany,theNetherlands,SwedenandSaudiArabia).
TheresultsshowthattheWashOnewithwashlethasabetterglobalenvironmentalperformance
thantheconventionalsystem,evenforlowuse.Italsorevealsthattheusephasehasthehighest
contributiontoimpactsduetoelectricityconsumption.Userlocationanalysisfurthershowsthat
Swedenhasthelowestenvironmentalimpact,whileGermanyandtheNetherlandshavethehighest
potentialforimpactreductionwhenchangingfromaconventionalsystemtotheWashOne.Based
ontheoverallresults,somerecommendationsareprovidedtoenhancetheenvironmental
performanceofinnovativetoiletsystems,namelytheoptimizationofthewashletusepatterns.This
articlehighlightstheimportanceofperformingaLCAatanearlystageofthedevelopmentof
innovativetoiletsbyidentifyingthecriticalissuesandhotspotstoimprovetheirdesignand
performance.
Keywords:bidet;eco‐design;energysavings;life‐cycleassessment;toilet;userbehavior;washlet;
watersavings

1.Introduction
Buildingsarerecognizedasoneofthehighestusersoffreshwater,consuming
enormousamountsofenergyandwaterresourcesand,ultimately,generatinghigh
environmentalimpacts.Thewatercycleofbuildingsrequiresagreatamountofenergy
duetorawwatertreatmentanddistribution,useinbuildings(domestichotwater),and
wastewatertreatment[1].Waterheatingrepresents13%ofenergyconsumptionin
residentialbuildings[2],withconventionaltoiletsystemshavingasignificantshare[3].
Citation:Rodrigues,C.;Almeida,J.;
Santos,M.I.;Costa,A.;Além,S.;Rufo,
E.;Tadeu,A.;Freire,F.Environmental
Life‐CycleAssessmentofanInnovative
MultifunctionalToilet.
Energies2021,14,2307.
https://doi.org/10.3390/en14082307
AcademicEditor:IoanSarbu
Received:2March2021
Accepted:15April2021
Published:19April2021
Publisher’sNote:MDPIstays
neutralwithregardtojurisdictional
claimsinpublishedmapsand
institutionalaffiliations.

Copyright:©2021bytheauthors.
LicenseeMDPI,Basel,Switzerland.
Thisarticleisanopenaccessarticle
distributedunderthetermsand
conditionsoftheCreativeCommons
Attribution(CCBY)license
(http://creativecommons.org/licenses
/by/4.0/).


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Innovativetoiletsystemscansavewaterandenergy,buthavehigherembodied
impactsassociatedwithmaterialsandelectroniccomponents.Environmentallife‐cycle
assessment(LCA)canbeappliedtoevaluateandcomparealternativetoiletsystems
(conventionalandinnovative),providingaholisticassessmentfromcradletograveand
avoidingburdenshifting.Inparticular,itisimportanttoanalyzetrade‐offsbetween
increasedembodiedimpactsandoperationalsavingsofinnovativetoiletsystems.
Additionally,LCAperformedinearlydesignstagesofthedevelopmentofproductscan
supportdesigndecisionsbeforeinnovativeproducts’oremergingtechnologies’entryinto
themarket,revealingthebenefitsofconsideringenvironmentalperformanceasadesign
constraint[4,5].EmployingLCAsininnovativeproductsenablesimprovedproducteco‐
designthroughearlyhotspotdetectionallowingoptimizationofmaterialchoicesanduse‐
phaseefficiency.LCAshavebeenusedtoassesstheenvironmentalperformanceofseveral
innovativesystems/products,particularlyinthebuildingsector[6–9].
LCAmethodologyallowstheidentificationofhotspotsbyquantifyingthebenefits
ofaproductorsystemandimprovementopportunitiesfortheirenvironmental
performance.SomeLCAstudiesoftoiletsystemsavailableintheliteraturefocusedonthe
productionphaseofceramicsanitaryware(cradle‐to‐site)[10,11].ThereareseveralLCA
studiesfocusedonwastewatertreatment(WWT)forconventionaltoiletsandsource‐
separationsystems[12–15],whileothersexaminealternativewatersourcesfortheflush
system(rainwater,seawater,greywaterreuse)[16–23].Lametal.,2017assessedthe
energyefficiencyofnon‐potablewatersystems(includingtoilets)fordomesticuse[24].
Gnoattoetal.,2019evaluatedthelife‐cycleimpactsofdifferentsolutionsfortoiletflush
systems,particularlycomparingsingleanddoubleflush[25].Theproductionphaseofa
toiletsystemisoftenneglectedinLCAstudiesoftoiletsystemsbecauseitscontribution
tothetotallife‐cycleimpactsisusuallylow(takingintoaccounttheextendedlife‐timeof
thesesystems),butalsobecauseincomparativestudiesofalternativeWWTsystemsitis
usuallyassumedthatthetoiletisthesame,sotheimpactofthesanitarywareisthesame
inallscenarios.Regardingthe“washlet”system,therearenocomprehensiveLCAstudies
onthesetypesofsystems.
Severalgapswereidentifiedregardingtheenvironmentalassessmentofinnovative
toiletsthathaveneverbeenaddressedintheliterature.Firstly,therearenostudies
performingacradle‐to‐gravelife‐cycleassessmentoftoilets,particularlytheinnovative
ones.Additionally,thereisaneedtoaddressthetrade‐offsbetweenthepotentialenergy
efficiencyofinnovativetoiletsandtheincreaseintheenvironmentalimpactsdueto
energyconsumption,particularlyinthenewwashingfunctions,aswellastheuseof
criticalmaterialsinelectroniccomponents.Finally,thesetoiletshaveaworldwidemarket,
differentfromconventionalmodels,whichcanhighlyinfluencetheirenvironmental
performanceduetotransportationimpacts,aswellasaffectingthecountry‐specific
electricitymixthatcanvarydependingonthefinaluserlocation.Tosumup,innovative
toiletshaveneverbeenstudiedinalife‐cycleperspectivetoassesstheirenvironmental
performanceandpotentialenergyefficiencybenefitsduetotheirmultifunctionality.
WashOneisaninnovativemultifunctionaltoiletthatincorporatesaself‐cleaning
system(calledawashletsystem,toreplacetheconventionalbidet),andanintegrated
waterstorageandflushsystem[26].ArenderingoftheWashOnetoiletsystemis
presentedinFigure1.ThismultifunctionaltoiletisbeingdevelopedbyaPortuguese
consortiumcomprisingtwocompaniesfromthesanitarywareindustry(OLIand
Sanindusa),acompanyprovidingelectronicengineeringsolutions(Evoleo)andseveral
highereducationinstitutions(UniversityofAveiroandUniversityofCoimbra)and
appliedresearchinstitutions(Itecons,PortugueseAssociationforQualityinBuildings’
WaterInstallations‐ANQIP).

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Figure1.Renderingoftheinnovativemultifunctionaltoilet(WashOne).Source:Developedbya
subsetofauthors.
The“washlet”systemincorporatesconventionalbidetfeaturesintothetoilet,
respondingtoarecentmarkettrendforhighstandardsofcomfortandhygiene.Thewater
storageandflushsystemintegratedintothetoiletmeetsthecompactnessneedsrequired
bycurrentdesignsolutions(reducingthevolumeoccupied)andallowstheoptimization
oftheflushingsystemandconsequentlytheuseofwater.
Thegoalofthisarticleistopresentanenvironmentallife‐cycleassessmentofan
innovativemultifunctionaltoiletsystem(WashOne),fromcradletograve,considering
twoalternativeWashOneconfigurations(withorwithoutwashlet)comparedwith
equivalentconventionalsystems(toiletandbidet,orjusttoilet,respectively).
Additionally,twoscenarioanalyseswereconductedtoinvestigatetheperformanceofthe
innovativetoiletwithwashletwhenvariationsareintroducedintermsof:(i)user
behaviorand(ii)userlocation.
2.MaterialsandMethods
TheLCAmethodologyappliedtoassesstheenvironmentalperformanceofthetoilet
systemsfollowstheISO14040:2006andISO14044:2006standardstoguidethemethods,
modeldevelopmentandinventorycalculationsinthisresearch.LCAisdevelopedinfour
interrelatedphases:goalandscopedefinition;life‐cycleinventory(LCI);life‐cycleimpact
assessment(LCIA);andinterpretation.Section2.1presentsthegoalandscopedefinition,
includingthelife‐cyclemodel,andSection2.2presentsthelife‐cycleinventoryanalysis.
2.1.GoalandScopeDefinition
Acradle‐to‐gravelife‐cycle(LC)modelwasdevelopedfortheWashOnetoilet.The
systemboundariesarepresentedinFigure2andencompassalllife‐cyclephasesincluding
wastewatertreatmentduringusephaseandtransportationbetweenandwithineach
phase.ThemainLCphasesofatoiletsystemare:(i)productionofthetoilet,auxiliary
systemsandsystem’sinfrastructure(piping,etc.);(ii)distributiontothefinaluser(in
Portugal,asreferencescenario);(iii)useinaresidentialbuilding;and(iv)end‐of‐lifeof
thecomponentsafter15yearsofservicelife(accordingtotheproducers).

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Figure2.Life‐cyclemodel(“cradletograve”)ofWashOne.Source:Developedbyasubsetof
authors.
TheWashOnetoiletincorporatesmultiplefunctions,particularlythe“washlet”,a
self‐cleaningsystem(toreplacetheconventionalbidet),andanintegratedwaterstorage
andflushsystem.Regardingthe“washlet”system,itaimstoreplacethebidetfunctions
withinthetoiletinordertoaddresshighcomfortandhygieneconditions.Itis
incorporatedinthelidandincludesthefollowingfunctions:lidlifterfunction,remote
control,WCseatwithseatheating,dryerarmwithdryernozzle,sprayarmwithspray
nozzleandladyshowernozzle,sprayshield,andodorremoval.
ThescopeofthestudyincludestwoWashOneconfigurations:WashOnewithand
withoutwashlet(WO1andWO2,respectively),bothofthemwithanintegratedwater
storageandflushsystem.TheWO1iscomparedwithaconventionaltoiletandbidet
(high‐end),whiletheWO2iscomparedonlywithjusttheconventionaltoilet,assuming
thatthereisnoadditionalcleaningsystemasabidet.Additionally,twoscenarioanalyses
wereconductedforWO1andtheconventionalsystem:(i)userbehaviorscenarioanalysis
and(ii)userlocationscenarioanalysis.Fortheuserbehavior,twoalternativewashlet
usagepatternswereassessed:onewherethewashletisusedinalltoiletvisits(W100);and
anotherwherethewashletisonlyusedinmajorvisits,i.e.,onevisitperdayperperson,
representing25%ofthedailyvisits(W25).Fortheuserlocationscenarios,fouralternative
locationswereassessed(Germany,theNetherlands,SwedenandSaudiArabia)and
comparedwithPortugal(referencescenario).Thefunctionalunitselectedistheuseofa
toiletsystem(conventionaltoiletandbidetorWashOne)bya4‐personfamily(twoadults
andtwochildren)livinginasingle‐familyhouseforoneyear(family×year)fortwotypes
ofuse:(a)withcleaningsystem(WO1)and(b)withoutcleaningsystem(WO2),assuming
aconventionaldailyusagepattern(definedinSection2.2.2).
2.2.Life‐CycleInventoryAnalysis
TheLCinventorywasdevelopedusingprimarydatafromthecompaniesinvolved
inthedevelopmentoftheWashOnetoilet(materialcharacteristicsandquantitiesof
mechanical,plasticandelectroniccomponents),complementedwithsecondarydatafrom
theliteratureandtechnicalreports,aswellaslife‐cycledatabases(Ecoinvent)[27–30].The
energyandwaterusedatawereprovidedbythemanufacturerandcollectedbasedon
experimentaltests.Section2.2.1detailstheinventorydataforproductionanddistribution

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fromproductionsitetothebuildingsite(users’location).Section2.2.2presentsusephase
andend‐of‐lifeinventoryanalysis.
2.2.1.ProductionandDistribution
Theproductionphaseofthetoiletsystems(WashOneandconventional)includes
productionofcomponentsandfinalproductassemblage.TheWashOnesystemhasa
ceramicstructureinvitreouschina,flushmechanismsandtwoplasticstoragetanks
(severalmechanicalcomponents(motors,pumps,etc.),andelectronics.Thecorestructure
ismadeofceramic(vitreouschina)withaseatmadeofduroplast.Theconventionaltoilet
includesaceramicstructure,alsoinvitreouschina,aseat(madeofduroplast),aceramic
storagetankandaflushmechanism(madeofpolystyrene(PS)).Table1presentsthemain
inventorydataofmaterialsandcomponentsoftheWashOneandconventionaltoiletand
bidet.Thisdataisaggregatebymaterialorcomponent(whenthematerialscomposition
ofeachcomponentisnotavailable),inthiscaseproxydatawasused.Primarydata
(materialcharacteristicsandquantities)wereprovidedbythecompanies.Detailed
informationofeachcomponentwasnotpresentedduetoconfidentialityissues.
Secondarydataforcomponents,materials(thermoplasticpolymers)andplastic
transformationprocesses(injectionforacrylonitrilebutadienestyrene(ABS),and
polypropylene(PP),polycarbonate(PC)andduroplast,andthermoformingforPS)were
obtainedfromEcoinventv3.1database[27–30].Theproductionoftheceramicstructure
(vitreouschina)wasmodelledusingEcoinventv3.1database[27]andEnvironmental
ProductDeclaration(EPD)databases.TheplasticcomponentsoftheWashOneare
producedonsite,intheplantwherethefinalassemblingisperformed,locatedinAveiro,
Portugal.Theelectronicandmechanicalcomponentsandceramicstructureareproduced
off‐sitebyseveralsuppliers.Thisinnovativetoiletisstillcurrentlyinaprototypephase;
however,accordingtotheassemblageschemedevelopedbythecompanyforafuture
productionline,thecomponentswillbeassembledmainlymanually,sotheenergy
neededforthisprocesswillberesidual(~0.01kWhperfinalproduct)andcanbe
neglected.
Table1.BillofmaterialsofWashOne(WO1andWO2)andconventionalcounterparts(toiletand
bidet).Source:DevelopedbytheauthorsusingdatacollectedbytheauthorsaffiliatedwithOLI
andSanindusacompaniesandfromtheliterature.
Materials/ComponentsWO1WO2ToiletBidet
(kg)
AcrylonitrileButadieneStyrene(ABS)4.142.76‐ ‐
Aluminum0.050.00‐ ‐
Battery0.100.00‐ ‐
Cardboard8.508.5055
Ceramic(vitreouschina)17.017.050.427.6
Controlunit0.300.00‐ ‐
Copper0.040.00‐ ‐
Duroplast3.603.882‐
Fans0.070.05‐ ‐
Motors12V0.570.37‐ ‐
Polypropylene(PP)0.101.98‐ ‐
Polystyrene(PS)0.500.501‐
Polycarbonate(PC)0.010.01‐ ‐
Pumps40W3.003.42‐ ‐
Rubber0.060.06‐ ‐
Electronics(sensors)0.020.02‐ ‐
Steel0.910.66‐ ‐
Waterheater0.140.00‐ ‐
Totalweight41395833
TheWashOnetoiletsaredistributedbyroadusinglorriesand/orship(sea
containers)fromtheproductionsite(Aveiro,Portugal)tilltheend‐userdestination(200

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km).Alternativeuserlocationshavebeenmodeledinascenarioanalysisforfivepotential
marketsidentifiedbythemanufacturerconsortium:inEurope(Portugal,Germany,the
NetherlandsandSweden);andintheMiddleEast(SaudiArabia,relevantconsumersof
advancedtechnologytoiletsystems).Foreachlocation,transportationdistances,
distributionmodesoftransportation,andcountry‐specificelectricitymixesfortheuse
phasewereassessed.Transportationdistanceswerecalculatedbasedonthedistance
betweentheproductionsiteandapotentialfinaluserlocatedinthecapitalofeach
country.ForlocationsinEurope,themodeoftransportationwasa16‐tonlorry,but
distributionbyshipwasalsoconsideredforSwedenandtheNetherlandsduetoport
areas’proximity.FortheMiddleEast,distributionwasassumedtobebyboatandalorry
forinlanddistance.Transportbyplane,trainandshipweremodelledusingprocesses
fromtheEcoinventv.3.1database[31].Transportationdataforthealternativelocations
arepresentedinTable2.
Table2.Transportcharacterizationfordistribution,consideringalternativelocationscenariosfortheWashOnetoiletwith
washlet(WO1)andrespectiveconventionalsystem(toilet+bidet).Source:Developedbytheauthorsusingdatacollected
bytheauthorsaffiliatedwithOLIandSanindusacompaniesandfromtheliterature.
UserLocationModeofTransportationDistanceWO1
(41kg)
Conventional
ToiletandBidet
(91kg)
(km)(tkm1)
Portugal(PT)Lorry16ton—EURO5200818
Germany(DE)Lorry16ton—EURO52700111246
TheNetherlands(NL)Lorry16ton—EURO5210086191
Boat(+lorry16ton—EURO5)1800(+130)74(+5)164(+12)
Sweden(SE)Lorry16ton—EURO53500144319
Barco(+lorry16ton—EURO5)3500(+150)144(+6)319(+14)
MiddleEast
(SaudiArabia—SA)Boat(+lorry16ton—EURO5)10000(+230)410(+10)910(+21)
1Tonne×kilometer.
2.2.2.UsePhaseandEnd‐of‐Life
TheWashOneandconventionalsystemsusephaseweremodeledforaconventional
usagepatterndefinedassumingadailyuseofa4‐personfamily,twoadultsandtwo
children(inequallynumberofbothgenders,necessarytocharacterizethetypeofvisits),
inasingle‐familyhouse.Detailedassumptionsfollowadailyuseoffivevisits,including
fourminor(urine)andonemajor(feces)foreachperson.Thewholefamilyusesonlyone
toilet.Thetoiletisused351daysperyear(assumingthat14daysarespentawayfrom
homeonvacation).BoththeWashOneandconventionaltoiletshaveadualflushsystem,
withfull(6L)andhalfflush(4.5L)formajorandminorvisits,respectively.The
consumptionoftoiletpaperiseightsheetsforminorvisitsand15sheetsformajorvisits.
Theuseofbidetintheconventionalsystemisonlyformajorvisits(onevisitperdayper
person).Dataregardingtimeofuse,waterconsumptionandenergyconsumptionwas
basedonexperimentaltestsaswellasdatafromtheliteratureandEPDdatabases
assumingastandardusepattern.Tables3and4presenttheWashOne’selectricityand
wateruseperfunctionandvisit(majorandminor).Thebidetsystem’scharacteristicsand
energyandwaterconsumptionaredescribedinTable5.


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Table3.WashOneelectricityuseperfunctionpervisit(majororminor).Source:Developedbytheauthorsusingdata
collectedbytheauthoraffiliatedwithOLIandfromtheliterature.
FunctionComponentsPower(W)TimeofUse(s)ConsumptionPerUse
(kWh)
AutomaticlidlifterMotor3636.0×10−5
SeatheatingElectricalresistance603005.0×10−3
WashletnozzlecleaningPump1241×10−5
User’scleaning
Pump12**
**
Motor284.4×10−6
Waterheater1444**
**
WashletnozzleoscillationMotor2603.3×10−5
DryingFan5304.2×10−5
Electricalresistance122301.02×10−3
OdorremovalFan53004.2×10−4
Fullflush(majorvisits)Pump10851.5×10−4
Halfflush(minorvisits)Pump1082.928.8×10−5
*Dependsonthetypeofvisit(seeTable4).
Table4.WashOnewaterandenergyuse(washletandtoilet)pertypeofvisit(majororminor).
Source:DevelopedbytheauthorsusingdatacollectedbytheauthoraffiliatedwithOLIandfrom
theliterature.
WashletandToiletUseParametersTypeofVisit
MajorMinor
Washlet(rearposition)(feminine/frontposition)
Waterusageduration1(s)4520
Waterflowrate(L/min)0.65
Usedwatervolume(L)0.490.22
Waterheaterefficiency10.95
WatertemperaturedifferenceΔT1(K)30(40–10°C)
Waterheatingenergy2(Wh) 18.068.03
Airdryerusageduration1(s)30
Airflowrate(L/s)3.33
Airheaterefficiency10.98
AirtemperaturedifferenceΔT1(K)30(45–15°C)
Airheatingenergy3(Wh)1.02
Totalenergyconsumption(Wh)19.089.05
Toilet
Flushwaterusage(L)6.0(fullflush)4.5(halfflush)4
Flushflowrate(L
/
s) 1.20
Flushduration(s)5.002.92
Pumpmotorpower(W)108.0
Energyconsumption(Wh)0.1500.088
1Estimatedrealisticassumption.2Pumpmotorandwaterheater.3Airblowermotorincluded.4
EuropeanNormEN14055.
Auserbehaviorscenarioanalysiswasperformedtoassessalternativewashletusage
patterns.Thewashletuseischaracterizedintermsofuseintensity(numberofusesper
day).FortheWO1(WashOnewithwashlet)configuration,thefollowingtwoscenarios
wereanalysed:W100—washletusedin100%oftoiletvisits;W25—washletusedonlyin

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majorvisits(25%ofdailyvisits).W25scenarioassumesthatinminorvisitsthefemale
userwillusetoiletpaper.WO2configurationconsiderstheuseoftoiletpaperinallvisits.
TheelectricitymixwasmodeledusingspecificliteraturedataforPortugalbasedon
[32,33].Fortheothercountries,specificcountrymixeswereusedbasedonliteraturefrom
theEcoinventv.3.1database[34,35].
Table5.Toiletandbidetenergyandwateruseinventory.Source:Developedbytheauthorsusing
datacollectedbytheauthoraffiliatedwithOLIandfromtheliterature.
BidetSystem’sInfrastructure
Waterheater’sefficiency0.8
Pipinglength1(m)8
Waterflow(L/min)6.4
Watertemperaturedifference2—
∆
T(K)30
Hotwaterquantity(L) 4
BidetUsePerVisit
Energyuse(kWh)0.2
Wateruse(L)8
ToiletWaterUsePerVisit
Flushwateruse(L)
Halfflush(minorvisits)4.5
Fullflush(majorvisits)6
1Fromtheheatingsourcetillthebidet.2Differencebetweenroomtemperatureandthewarm
temperaturedefined.
TheWashOneandconventionalsystemsusephasesweremodeledassuminga
conventionalWWTsystemwithoutthetertiarytreatment(notincludedinmostWWT
plants)andassumingacountry‐specificenergymixdependingontheuser’slocation.For
thesecondarytreatment,ananaerobicprocess(sludgetreatmentwithoutoxygen)was
considered.Itwasassumedthatallthesanitaryresiduesfromthetoiletandbidet,
dependingonthesystem(urine,feces,toiletpaperandgreywater),areroutedfromthe
sewertoamunicipalWWTplantineachlocationassessed.Wastewatertreatmentswere
modelledusingtheEcoinventv.3.1database[36].
Fortheend‐of‐lifeofthecomponents,itwasconsideredthattheceramicmaterialis
disposedofinlandfillforinertmatter,steelcomponentsarerecycled,andtheelectronic
componentsareincineratedorrecycleddependingontheircomposition.Plasticmaterial
isrecycledorincinerated(withenergyrecovery)dependingonitsstructure.The
cardboardofthepackageisassumedtoberecycled.Theremainingmaterialsand
componentsareincinerated.WastetreatmentsweremodelledusingtheEcoinventv.3.1
database[29,36].
3.Results
3.1.ComparativeAssessmentandUserBehaviorAnalysis
EnvironmentalimpactswereassessedusingtwocomplimentaryLCIAmethods:
CED(CumulativeEnergyDemand)wasusedtocalculatethenon‐renewableprimary
energy(NRPE),toaddressfossilenergyresourcedepletion;andtheCML‐IAwasusedto
evaluatefivemid‐pointcategories:GlobalWarming(GW),followingIPCC2013foratime
horizonof100years,Acidification(A),Eutrophication(E),OzoneDepletion(OD)and
PhotochemicalOxidation(POC).Thesecategorieswereconsideredtobethemostrelevant
bytheEU[37,38],aswellasrecommendedbyseveralproductcategoryrules(PCR),
namelyPCRofsanitarywareandbuildingproducts[39,40].Figure3showstheresultsfor
thetwoWashOneconfigurations(WO1andWO2,withandwithoutwashlet,
respectively),includingthetwowashletusescenarios(W100andW25),comparedtothe

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conventionalsystems.Theconventionalsystem(toiletandbidet)presentshigherimpacts
thanWO1(inbothwashletusescenarios)forallimpactcategories.However,whenthe
WashOnedoesnotincludethewashletsystem(WO2),ithashighertotalLCimpacts(1–
8%)thantheconventionaltoiletinthreeoutofsiximpactcategories(acidification,
eutrophicationandphotochemicaloxidation).Whencomparingtheusescenarios,the
W100hashigherimpactsthanW25inallimpactcategoriesassessed.Theenvironmental
impactsareshowntobedrivenbytheusephase(71–95%oftotalLCimpactsforthe
WashOneand92–98%fortheconventionaltoilet)inalltoiletsystemoptionsforallimpact
categoriesassessed,followedbymaterialsproductionandcomponentsmanufacturing(5–
29%fortheWashOneand2–7%fortheconventionaltoilet).
Usephaseresults,presentedinFigure3b,showthatforWO1‐W100,thehigh
contributionoftheusephaseisduetoelectricityuseofthewashlet(climatechange,ozone
depletionandphotochemicaloxidation),wastewatertreatment(acidificationand
eutrophication)andflushwater(non‐renewableprimaryenergy).ForWO1–W25,the
processeswiththehighestimpactaretoiletpaper(climatechange,ozonedepletion,
photochemicaloxidationandnon‐renewableprimaryenergy)andwastewatertreatment
(acidificationandeutrophication).Themaincontributortotheconventionalsystem(toilet
andbidet)usephaseimpactsaretheelectricityuseofthebidet(climatechange,ozone
depletionandphotochemicaloxidation),toiletpaper(acidificationandnon‐renewable
primaryenergy),andwastewatertreatment(eutrophication).ForWO2andtoilet,theuse
oftoiletpaperhasthehighestcontributionforfiveoutofsixcategories,withtheexception
ofeutrophication,wherewastewatertreatmentprocessisthehighestcontributor.Energy
consumptioncontributesforabout30%ofthetotalLCimpactsofWashOneand30–65%
oftheconventionaltoiletinmostofthecategoriesassessed.Waterconsumption
contributesforabout15–30%oftotalLCimpactsofWashOneandabout10%ofthe
conventionaltoiletinfouroutofsixcategories.


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Figure3.LCIAresultsofthealternativetoiletsystems(WashOneandconventionaltoiletsystem)perfamily×year:(a)LC
impactsand(b)usephaseimpactsbreakdown.
Contributionanalysisoftheproductionphase(includingmaterialsproductionand
componentsmanufacturing)havehighlightedthekeydriversofenvironmentalimpacts
foralternativetoiletsystems.Figure4showsthatthekeycontributorsarethewashlet(26–
36%)followedbytheintegratedflushsystem(15–28%)fortheWO1.Themain
contributorstotheproductionphaseoftheconventionalsystemandWO2aretheceramic
structure(45–69%)andtheintegratedflushsystem(14–18%),makingupover60%ofthe
totalproductionimpacts.Regardingmaterialscontribution,plasticscontributeabout30–
45%totheproductionimpactsoftheWashOnesystem,whileelectroniccomponents
contributeabout30–65%infouroutofsixcategories(GW,NRPE,AandE).Plastics
contributeabout90%oftheend‐of‐lifeimpactsofmaterialsusedfortheproductionofthe
WashOne.Theseresultshighlightthatthereispotentialforimprovementinthe
productionoftheWashOnecomponents,particularlyplasticmadecomponents,for
instance,byincorporatingrecycledrawmaterialandreducingproductionlosses.

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Figure4.LCIAresultsfortheproductionphaseofthetoiletsystems(cradletogate)perfamily×year.
3.2.UserLocationScenarioAnalysis
Theuserlocationanalysiswasperformedforfivealternativelocations.Foreach
location,threeparameterswereassessed:thecountry‐specificelectricitymixthat
influencestheenergyuseduringtheusephase;andthetransportationdistanceandmode
forthedistributionfromtheproductionsite(Portugal)toeachspecificlocation.Results
presentedinFigure5showthattheusephaseisthemaincontributortothetotalLC
impactsinalllocations,duetotheenergyuseineachcountry(andconsequentlythe
country‐specificelectricitymix).Swedenpresentsthehighestdistributionimpactsdueto

Energies2021,14,230712of16
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thelargedistancestraveledbylorry(3500km),butstillwithverylittleinfluenceinthe
totalLCimpacts(lessthan5%).



Energies2021,14,230713of16
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Figure5.UserlocationanalysisLCIAresults,consideringfivealternativelocations(Portugal(PT),Germany(DE),the
Netherlands(NL),Sweden(SE)andSaudiArabia(SA))andtwotransportationmodes(lorryandship).
WO1–W100andconventionaltoiletsystemshavethelowestenvironmentalimpacts
inSweden(SE)owingtothehighpercentageofrenewableenergy(morethan80%)inthe
Swedishelectricitymix,formostcategories(GW,NRPE,AandPOC).WO1‐W25hasthe
lowestimpactsinSaudiArabia(SA)formostcategories(NRPE,A,EandPOC).The
conventionaltoiletsystemhasveryhighimpactsinSAforallimpactcategoriesexcept
eutrophication,duetohighpercentageofoil(about60%)combinedwithnaturalgas
(about40%)usedfortheproductionofelectricity.GermanyandtheNetherlandshavethe
Globalwarming(GW)Non‐renewableprimaryenergy(NRPE)

Acidification(A)Eutrophication(E)

Ozonedepletion(OD)Photochemicaloxidation(POC)

Materialsproductionandcomponentsmanufacturing Distribution Use End‐of‐life

0
50
100
150
200
250
300
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
WO1‐W100 WO1‐W25 ConventionalToilet
+
Bidet
kgCO
2
eq
‐500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
WO1‐W100 WO1‐W25 ConventionalToilet
+Bidet
MJ
‐0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
WO1‐W100 WO1‐W25 ConventionalToilet
+Bidet
kgSO
2
eq
‐0.5
0.0
0.5
1.0
1.5
2.0
2.5
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
PT
DE
NL‐lorry
NL‐ship
SE‐lorry
SE‐ship
SA
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+Bidet
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15
20
25
30
PT
DE
NL‐lorry
NL‐ship
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SE‐ship
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NL‐lorry
NL‐ship
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30
40
50
60
70
80
PT
DE
NL‐lorry
NL‐ship
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eq

Energies2021,14,230714of16
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highestimpactreductionpotentialwhenchangingfromaconventionaltoilettoWashOne
(reductionof52–71%intotalLCimpacts).
4.ConclusionsandRecommendations
Anenvironmentallife‐cycleassessment(cradletograve)ofaninnovative
multifunctionaltoiletsystem(WashOne)wasperformed,consideringalternative
configurations(withorwithoutwashlet),comparedwithconventionalsystems.
Additionally,twoscenarioanalyseswereconductedtoinspecttheimpactofdifferentuser
behaviorsanduserlocationsontheenvironmentalperformanceofthesesystems.Forthe
userbehaviorscenarios,twoalternativewashletusagepatternswereassessed,onewhere
thewashletisusedinalltoiletvisits(W100)andanotherwherethewashletisonlyused
inmajorvisits(W25).Fortheuserlocationscenarios,fouralternativelocationswere
assessed(Germany,theNetherlands,Sweden,SaudiArabia)andcomparedwithPortugal
(referencescenario).
ItcanbeconcludedthattheWashOnesystemwithwashlet(WO1)hasabetter
environmentalperformancethantheconventionalsystem(toilet+bidet),whilewithout
washlet(WO2)presentssimilarperformancetotheconventionaltoilet.Theusephasehas
thehighestcontributiontothelife‐cycleimpactsinbothWashOneconfigurationsand
scenariosassessed.ThehighestcontributiontotheusephaseimpactsforWO1is
electricityuse(washletandintegratedflushsystem),whileforWO2itistoiletpaper.In
theconventionalsystem,electricityuseforthewaterheatersystemofthebidethasthe
highestcontributionfortheusephase.Itisworthnotingthatevenwhenthewashlet
systemhaslowuseintensity(W25),theWashOnesystemhasstillabetterperformance
thantheconventionalone.
UsephaseisthemaincontributortoLCimpactsinalllocations,duetotheenergy
useineachcountryand,consequently,thecountry‐specificelectricitymix.Itisworth
notingthatthemarketwiththehighestpotentialfortheWashOnetobecompetitivein
termsofenvironmentalperformanceistheNorthofEurope,inthisstudyrepresentedby
Sweden,asitpresentedthelowestLCimpactsinmostcategories,independentofthe
modeoftransportationusedfordistribution.AlthoughSwedenpresentsthehighest
distributionimpactsduetothelargedistancestraveledbylorry(3500km),theyhavevery
littleinfluenceintheLCimpacts(lessthan5%).Additionally,Germanyandthe
Netherlandshavethehighestpotentialforimpactreductionwhenchangingfroma
conventionaltoilettoWashOne(reductionof52–71%LCimpacts).
Drawingontheresultsandonlimitationsofthisarticle,recommendationsto
enhancetheperformanceofinnovativetoiletsystemsareprovidedasfollows.Variability
anduncertaintyanalysisshouldbeincorporatedintheLCA,andtheusephase(highest
potentialforimprovement)shouldbecomprehensivelyassessed,astheresultswere
basedonastandardusepattern(fromexperimentaltestsatlabscale).Futureworkshould
alsoassessstrategiestoimproveenergyuseefficiencyandtominimizewateruseineach
visit(e.g.,incorporateaflowreducer,adjusthotwatertemperature).Toiletproduction
canalsobeimproved,inparticularplasticscomponents,byincorporatingrecycled
materialandreducingproductionlosses.Bio‐basedmaterialscanalsobeusedasan
alternativetofossil‐basedpolymers.
ThisarticlehighlightstheimportanceofperformingLCAatanearlystageof
developmentofinnovativeproductsbyidentifyingthecriticalissuesandhotspots(the
maincontributorsforenvironmentalimpacts)toimprovetheirdesignandperformance.
Italsoshowsthesignificanceoftheusephaseintoiletsystems,givingdirectiontofurther
developmentsoftheWashOnesystem.Itisimportanttomentiontherelevanceof
addressingtheusephaseinPCRs(and,consequently,inEPDs)oftoiletsystems.
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AuthorContributions:A.C.providedthedataforthelife‐cyclemodelandinventory;S.A.and
E.R.providedthedataforthelife‐cyclemodelandinventory,aswellastherenderingpresentedin
Figure1;J.A.,M.I.S.andA.T.alsoprovideddata,contributedtothedataanalysisandreviewed
thepaper;C.R.andF.F.performedtheanalysis,interpretedtheresultsandwrotethepaper.All
authorshavereadandagreedtothepublishedversionofthemanuscript.
Funding:ThisresearchhasbeensupportedbyFEDER(EuropeanRegionalDevelopmentFund)
throughCompete2020(OperationalProgramCompetitivenessandInternationalization)underthe
WashOneprojectgrant(POCI‐01‐0247‐FEDER‐017461).Thisworkhasalsobeensupportedby
FundaçãoparaaCiênciaeTecnologia—FCTthroughprojectsCENTRO‐01‐0145‐FEDER‐030570
(SET‐LCA)andM‐ERA‐NET2/0017/2016(CTBBasics).
InstitutionalReviewBoardStatement:Notapplicable.
InformedConsentStatement:Notapplicable.
DataAvailabilityStatement:Thedatapresentedinthisstudyarepartlyavailableonrequestfrom
thecorrespondingauthor.Thedataarenotpubliclyavailableduetoprivacyissues.Detaileddata
regardingcomponentsandfunctionalitiesoftheinnovativetoiletisnotavailableduetopatent
confidentiallyissues.
Acknowledgments:TheauthorsarealsogratefultoallpartnersoftheWashOneprojectfortheir
contribution,andparticularlytoPedroMarquesforhisvaluablefeedbackinconductingthis
research.Theopenaccesspublicationcostswerealsocoveredbytheprojects.
ConflictsofInterest:Theauthorsdeclarenoconflictofinterest.
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