Towards a circularity indicator to assess products’ materials and lifetime : in-use occupation

Procedia CIRP 90 (2020) 10–13

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Procedia CIRP

journalhomepage:www.elsevier.com/locate/procir

Towards a circularity indicator to assess products’ materials and lifetime: In-use occupation

Gustavo Moraga

, Sophie Huysveld

, Steven de Meester

, Jo Dewulf

aResearch Group Sustainable Systems Engineering (STEN), Ghent University, Coupure Links 653, 90 0 0, Ghent, Belgium

bDepartment of Green Chemistry and Technology, Ghent University, Graaf Karel de Goedelaan 5, 8500, Kortrijk, Belgium

a rt i c l e i nf o

Keywords:

Circular economy Circularity Indicator Resource Lifetime

a b s t ra c t

Slowingandclosingloopstrategieshavetheultimategoalofavoidingmaterials’losses,hibernation,and emissions,thereforeallkindofactions thathamperusefulapplications.Consequently, thereisaneed todevelopindicators thatcandealwithmassand time.Away toindicatecircularityisbymeasuring thein-useoccupationofresources,thatis,keepingmaterialsinausefulstate,avoidingdissipation,and adverseeffects,suchasburdentransfer.Theobjectiveofthisworkistoadvancein-useoccupationasan indicatorforthecircularityofproducts;therefore,weschematicallypresentaframeworkandparameters forsuchindicators.

© 2020TheAuthor(s).PublishedbyElsevierB.V.

ThisisanopenaccessarticleundertheCCBY-NC-NDlicense.

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1. Introduction

Circular Economy (CE) is an umbrella concept (Blomsma and Brennan,2017;CIRAIG2015)thatcoversthereductionofmaterial inputandwastegeneration(EEA2016)to decoupletheeconomic growthfromtheuseofnaturalresources(Pauliuk,2018).Although CEmaynotbeconsideredanewconcept(BSI2017),itincludesthe useofexistingstrategiesinanewway,promotingaparadigmatic shiftintheeconomy(BlomsmaandBrennan,2017;BSI2017).Indi- catorsareusefultoolstoassesstheprogresstowardsCEtransition (Gengetal.,2012).However,a reviewshowedthatonlyalimited fractionof recentCE studies focuseson the developmentor dis- cussionofindicators(Ghisellini etal., 2016). Mostoftheexisting indicatorsevaluatenations,regions andindustrialparks,butindi- catorstoevaluatecircularityinbusiness andproductsareappear- ing(Pauliuk,2018).Recently,theEuropeanUnion(EU)established anactionplantoimplementCE(EC2015).

Consideringthe pluralityofCEmeanings, lackofclarity inin- dicators may drive to different or incoherent outcomes. To bet- ter understand what CE indicators are measuring, Moraga et al.

(2019) developed a framework to classify indicators accordingto CE strategies and measurement scope. The authors applied the frameworkonseveralCEindicatorsattheproductlevelasarepre- sentationforthemicro-scaleassessment.Theirframeworkshowed

∗ Corresponding author.

E-mail address: [email protected] (G. Moraga).

that severalindicatorsanalyseonly materials,andthere areindi- cators yet to be built. Pauliuk (2018) claimsthat material cycles (natural resource depletion, in-usestock, and lifetime) should be thefoundationofCEindicators.Noticeably,although CEconsiders lifetimeasessentialtokeepproductsinausefulstate,fewindica- torsdealwithtimeasaparameter.

Wearguethattwomaincomponentsarenecessarytomeasure thecircularity ofproducts:thematerials’ massandthetime that productsareinthein-usestate.Thispaperproposesapossibleap- proach for an alternative indicator that captures mass and time.

Theoutlineisasfollows:RevisionofexistingCEindicatorsmeasur- ingtime (Section 2),in-useoccupationasalternative CEindicator measuringtimeandmass(Section3),thedefinitionofparameters andpreliminaryindicatorforin-useoccupation(Section4),andfi- nallyweaddressconclusionsandfutureperspective(Section5).

2. CEindicatorsthatconsidertimeasaparameter

Mass related indicators are commonly used to assess CE in products,e.g.withrecycling,collection,andrecoveryratesorother resourceefficiencymetrics.Manyofthoseindicatorsarebasedon worksthat areprevious to theterm‘circular economy’.Indeed,a review ofthe periodbetweenthe1970sand1990sshowedarel- evant development of material flows indicators (Fischer-Kowalski andHüttler,1998).BlomsmaandBrennanreasonthatstrategiesin thisperiodevolvedfromhandlingwasteanditspollution effects, e.g. waste-to-energy, to considering waste as a resource in more complexsolutions,e.g.cascading(BlomsmaandBrennan,2017).

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G. Moraga, S. Huysveld and S. de Meester et al. / Procedia CIRP 90 (2020) 10–13 11

As CE intends to retain materials for aslong aspossible, the timedimensionisalsoofconcern;however,thisdimensionhasre- ceived lessattention. Nonetheless,researchersandcompanies de- velopedsome indicatorstodealwiththelifetimeofmaterialsand products in closed-loopsupply chainsprior to the‘circular econ- omy’term.Forexample,thenumberoftimesmaterialsareusedin differentproductswascalculatedthroughMarkovchain(Matsuno etal.,2007;EckelmanandDaigo,2008);companiesdevelopedspe- cificindicatorstoestimatethepercentageofreturnedproductsand lifetime of products and distribution systems, such ascontainers and crates (Flapper et al., 2005). More recently, despite a grow- ingnumberofnewcircularityindicatorsonproductlevel(Pauliuk, 2018),indicatorsoftendonot taketime asacentral aspectofCE.

Ontheproductlevel,twonotableexamplesconsidertime(Moraga etal.,2019).First,theMaterialCircularityIndicator(MCI)fromthe EllenMcArthurFoundation(EMF2015)and,second,theLongevity indicator (Figgeetal.,2018).We usethose worksasexamples of currentlydevelopedcircularityindicatorsincludingtime,otherin- dicators before theuse of ‘circular economy’term existbut they arenotdescribedhereforthesakeofbrevity.

The MCI (dimensionless) aims to improve decision-making in thedesignphaseofproducts.MCI(Eq.(1))measurescircularityby aggregatinginadimensionlessindicatortheso-calledLinearFlows Index(LFI),lifetime andtheintensityofuse.LFIisarelationofthe usedvirginmaterialandgeneratedwastedividedbytheproduct’s total mass andthe wastefraction fromthe upstream anddown- streamprocesses.Thelifetimeistheratiooftheproduct’s lifetime (L)overtheindustryaverage(Lav).Theintensityofuseistheratio oftheproduct’sfunctionalunit(U)overtheindustryaverage(Uav).

MCIresultscanbe showndisaggregatedpermaterialorinthefi- nalindexfortheentireproduct(weightingthematerials ontheir mass contribution). Eliaet al.(2017) found that amongother in- dicatorsandmethodologies, MCIisthe onlyonethat attemptsto assess theloss ofmaterials andproduct durability. The indicator, however,focusesonlyontherestoration ofmaterials and‘failsto addressothercirculareconomyissues’(CIRAIG2015).Indeed,MCI only analyses the product in its lifetime perspective and misses howtheproductcontributestosavingresourcesinabroadertime horizonperspective.

MCI=1−LFI×

Lav

Uav

(1)

Longevity(intime,e.g.monthsoryears)isaneco-efficiencyin- dicatorthatmeasurestheamountoftimearesourceisused;that is,accordingtotheauthors,avalue-orientedapproachratherthan burden-orientedone,suchastheapproachesconsideringenviron- mentalimpacts.The indicator(Eq.(2))isasumofthelifetimeof the product’s first use (L^A), the increased lifetimeif the product returnsforremanufacturing(L^B),andtheincreasedlifetimeifthe material is recycledin a newbut sameproduct by the company (L^C).Longevityindicatorisfocusedontheanalysisoftheresource useconsideringthedecisionmakingfromacompanyperspective, but disregard the burdens from material losses inside the com- panyoralongthevaluechain.SimilarlytoMCI,thisindicatordoes notaccountfortheproduct’scontributiontosavingresourcesina widertimeperspective.

Longe

v

A perspective with a broader time horizoncould show perti- nent informationwithprevious orfutureproducts’cycles,thatis, material circularity in differentcycles. Furthermore, a time hori- zonlongerthanoneproduct’scyclecoulddeliverthecallmadeby BlomsmaandBrennan(2017),i.e.tomoveawayfromassessments ofsingularCEstrategiesbyshowingtheminsequenceandparallel configurations.Indicatorsthatassessstrategieswithinoneproduct or business levelcould help decision inthisparticular boundary,

butthey are less helpful on policymakingand social level.Simi- larly,Eliaetal.(2017)highlightedthattheyarestillintheinfancy in measuring CE, and most of the indicators are related to the resource-usedimension,butthatCEcallsforabiggerpicture.We understand that more comprehensive monitoring of CE could be madethroughindicatorsmeasuring theuseofresources inprod- uctchains.

3. In-useoccupationasalternativeCEindicatormeasuring timeandmass

Scarcityofnaturalresourcesisofproperimportanceasthegoal ofCEis‘tomanageallnaturalresourcesefficientlyand,above all, sustainably’ (EEA 2016). Particularly forthe micro-level, the ulti- matescarcity ofmaterials relates to earth’s stockof virgin natu- ralresources (Figgeetal.,2017). Therefore,managingresources is vital,principally,fornon-renewableabioticones. Althoughabiotic resources cannot be destroyed (except by energy transformation andone-way spacemissions), they can indeedbe dispersed into eitherenvironmentortechnosphere(Frischknecht,2016).Meaning thattheextractionprocessdoesnotnecessarilyimplyunavailabil- ity: the not-yet-dispersed abiotic resources are rather borrowed and could be potentially restored thereafter (Frischknecht, 2016; ZamporiandSala,2017).Insteadofdepletion,wecouldassessthe inaccessibilityofresourcescausedbyhuman-made‘compromising actions’ (van Oers et al., 2019). Those actions regard e.g. explo- ration, environmental dissipation, technosphere hibernation, and in-useoccupation.

In-use occupation is a concept of particular interest for CE.

Managingresourcesefficientlymeans,inotherwords,maximising theoccupationinuse,thatis,avoidingdispersionandlossesofany kind. Occupyaresource inin-useproducts isthe purposeofany extracted resource (van Oers et al., 2019). In-useoccupation be- comesofincreasedrelevance to CEbecausesimilarly to‘landoc- cupation’ itcould be assessed withthe aidof a time dimension.

Forexample,asproposedbyvanOersetal.(2019),kg•year.

Moreover,theinclusionofdifferentcyclesofproducts,oracas- cading of materials in a sequential use of products, could show specific details fordissipation of resources, as specific character- istics of products can influence the dissipation, e.g. design, use, reparability,collectionsandtreatmentsystem.Inthatsense,prod- uctcycleswithhighercircularityavoiddissipationofresourcesand increasetheirin-uselifetime.Weclaimthatcircularityshouldcon- tributetomorein-useoccupationofresources,thatis,keepingma- terials ina usefulstate, avoiding dissipation, andadverse effects, suchasburdentransfer. Weaimto elaboratefurtheron thecon- ceptofin-useoccupationwithpossibleparametersandleadingin- dicators.Forthemoment,we restrictthescope totheanalysisof materialandtime,butfutureworkwillconsiderthepotentialad- verseeffects(increasedenergyuse,emissions,etc.)ofcircularity.

4. Definitionofparametersandpreliminaryindicatorfor in-useoccupation

Foravirgin-rawmaterialretainedinacascadingofproducts,at leastthree occupationphasescan be depicted ineach cycle(Fig.

1):supply,in-use,andhibernation.Supplyoccupationincludesall processes of transformation of resources (primary or secondary) intoin-useproducts. Inthelife cycleassessmentframework, this wouldcloselyrelatetoacradle-to-gratesystemboundarythatin- cludesmarketactivities, suchasretail.Similarly,thesupplyoccu- pationencompassesthereverseandforwardchannelsofdistribu- tionofreversesupplychainmodels,thatis,producers,distributors, collectors,andrecyclers(seee.g.Fleischmannetal.,1997).Thein- useoccupationisthephasewheretheproductiseffectivelyused;

it startsafterthe retail process andends before thehibernation.

12 G. Moraga, S. Huysveld and S. de Meester et al. / Procedia CIRP 90 (2020) 10–13

Fig. 1. Input and output mass (m), material losses (l) and time duration ( t) parameters for n cycles of a material in a product j.

Thehibernationphasestandsfortheproductsthatare notin-use butwaitingforanewsupplyphaseorend-of-life,e.g. aPET bot- tlebetween thediscard (in thetrash bin) andthe EoL collection foreitherfinaldisposalortreatment,oraforgottennon-functional batteryinashelfalsorepresentsthehibernationphase.

Notethatsupplyphaseofthe2ndproductandfollowingprod- uctscanincludeanystrategiestoincreasethelifetimeofproducts (e.g.repair, reuse,andrefurbishment)oranystrategiesto recover thematerialintheproducts(e.g.recycling).Therefore,afterthehi- bernationphase,aproduct could virtuallygo tothein-usephase (e.g. stockpiled mobile phone that is reused without any repair activity). In this way, the cascading ofproducts can consider CE strategiesinasequentialconfiguration.

For each occupationphase, it is possibleto trackthe mass of virginrawmaterial(m)dedicatedinitiallytothefirstproductthat is kept into the economy in other products. The supply phase beginswith raw-material productionas definedby Dewulfet al.

(2015).Eachphase has anidentifier forthisinput massof mate- rial (mS,mU, mH). Also, each occupation canhave lossesby the dissipation/dispersionof the evaluated material (lS, lU, lH). Most ofthe lossesare likelyto happen in the supply phase; however, somelossesmayalsohappen intheother phases,andtheyneed tobe takeninto account (e.g.oxidation). Moreover, each occupa- tionhas associatedtime durations(^{tS, tU, tH) measured in} accordancewiththeirtimeoccurrence.

After thisschematicdefinitionoftheparameters,itpossibleto drafta preliminary indicator forthe in-use occupationthat con- sidersbothmassandtime(Eq.(4))andtheadditionaloccupations (Eqs.(3)and(5)).OccS_j,OccU_j,andOccH_jarerespectivelythesup- ply,in-use, andhibernationoccupationofa materialinproduct j (kg.year).mS_j,mU_j,andmH_jare respectivelytheinputmassofa materialintothesupply,in-use,andhibernationphaseofproduct j(kg).lS_j,lU_j,lH_jarerespectivelythelossofamaterialduetothe supply, in-use, and hibernationoccupation (kg). ^tUj,^tUj, and ^tUjarerespectivelythesupply,in-use,andhibernationtimeofa productj(year).

OccSj=

mSj−lS_j 2

·

OccUj=

mUj−lU_j 2

·

OccHj=

mHj−lH_j 2

·

Theequationsshow twocomponents: amassrelationandthe timeparameter.Thosecomponentsareatwo-dimensionalrelation withtimeasx-axisandmassasy-axis(Fig.1)thatresultsinthe occupation‘area’.Therefore,thecalculationissimilartotheright- trapeziumarea(tworightangles)inwhichparallelsidesrelateto themass,andnon-parallelsidesrelatetotime.Thetrapeziumarea equationistheproductoftheaveragelengthsoftheparallelsides (mass)bythedistancebetweentheparallelsides(time).Themass relationcomponentintheEqs.(3)–(5),massattheinitialtimeof occupationminushalfofthelosses,ismathematicallyequaltothe averageofmassattheinitialandfinaltimeofoccupation.

5. Conclusionandperspectives

Circularityshould gobeyondthe measurementofthe massof resources; the lifetime of products is essential to indicate CE in the micro-scale. In this paper, we present a brief review of in- dicators that includetime asparameter, both MCI andLongevity presentscope limitationsthat needto be addressed,such as, the product’s contribution tosaving resources anda wider time per- spective. Here we presenta rationale forin-use occupation as a startingpointforthedevelopmentofaCEindicatorthataddresses theseissues.Weexpectthatthisindicatorcouldbeusefulfortwo stakeholders: (1) to industry for the design of products and the acknowledgement of the occupation of materials in each phase;

therefore, improving the occupation ofone product cycle. (2) To policymakersfortheassessmentoftheuseofmaterials indiffer- entcascadingscenarios;therefore,prioritisingpolicythatcouldin- creasetheoccupationofmaterialsinmorethanoneproductcycle.

This paper depicts the ongoing development of a research projectaimed toassess thecircularity of products. Moreover, we proposeandadvancethein-useoccupationasan indicatorofthe

G. Moraga, S. Huysveld and S. de Meester et al. / Procedia CIRP 90 (2020) 10–13 13

circularity of materials in products. For the time being, the in- troduced indicators could be used in one product cycle to test the importance of the in-use occupation concerning the supply and hibernationoccupations. Forexample, a one-useplastic gro- cerybagwouldhavealower in-uselifetimethanareusableplas- tic grocery bag; if the supply time were the same,the reusable bag wouldhave a better in-useoccupation. Futurework can ex- pandtheassessmentthroughperformanceequationsabletocom- parethewholeoccupationofmaterialsindifferentcyclesofprod- uctconsideringacascadingperspective.Forexample,theindicator couldmeasuretheoccupationoftheplasticbagthatwouldbere- cycled or reused in different cyclesconsidering specific lifetimes andlosses.

Other aspects are necessaryto advance, i.e.the transitionbe- tweencyclescouldbemadewithperformance indicatorscompar- ingeachcycle;theoverallcascadingofmaterialsindifferentprod- uct cycles could indicate the fraction of materials retained over a specifictime horizon;theassessmentofenergy-using products, environmentalimpacts, andenergytrade-offsforeachoccupation could improvethemeaningfulnessoftheresultsby includingen- vironmental concerns. Additionally, we intend to extend this re- search with case studies from literature andindustry. Therefore, itwillberelevanttoincreasetheliteraturereviewtocomprehend productdevelopmentandmanagement,e.g.lifetimeprediction,re- verse logistics,andcannibalisation,that willaffectthecasestudy examples.

CRediTauthorshipcontributionstatement

Gustavo Moraga: Conceptualization, Methodology, Investiga- tion,Visualization,Writing-originaldraft,Writing-review&edit- ing.SophieHuysveld: Conceptualization,Writing-review& edit- ing. Stevende Meester:Conceptualization,Supervision,Writing - review & editing. Jo Dewulf: Conceptualization, Funding acquisi- tion,Supervision,Writing-review&editing.

Acknowledgements

The authors are very grateful for full financial support re- ceived from the Flemish administration via the ‘Steunpunt Cir- culaire Economie’ (Policy ResearchCentre Circular Economy).The authors declareno competingfinancial interests. This publication containsthe opinionsofthe authors,not that oftheFlemish ad- ministration.The Flemishadministrationwillnotcarry anyliabil- itywithrespecttotheusethatcanbemadeoftheproduceddata orconclusions.

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