Eedi Methodology

8/2/2019 Eedi Methodology

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Methodology:

Shippingefficiency.org–EfficiencyRatingfor

ExistingShips

Summary

Theship“EnergyEfficiencyDesignIndex(EEDI)”hasbeenformulatedbytheIMOMarine

EnvironmentProtectionCommittee(MEPC)asameasureoftheCO 2emissionperformanceofships.

TheshipEEDIiscalculatedoncharacteristicsoftheshipatbuild,incorporatingparametersincluding

shipcapacity,enginepowerandfuelconsumption.

Shippingefficiency.orghasdevelopedamethodtocalculateanEEDIrating–oraswehavenamed

ourversion,EnergyEfficiencyRating‐thatcanbeusedtocomparetheenergyefficiencyofexisting

shipsofaparticulartypeaspartoftheShippingefficiency.orgRatingsystem.Theratingsforan

individualshiparecalculatedbycomparingtheEEDIvaluesforthatshiptooverallaveragevaluesfor

allshipsofthattype(e.g.bulkcarriers)andtoothershipsofasimilarsizewithinthistype.Shiptypes

areconsistentwiththoseusedbyIMOMEPC.

ThemethodforcalculatingtheGHGemissionratingsisdetailedinthisreport.

Introduction

Warmingoftheclimatesystemisnowconsideredtobeunequivocal,andevidentfromobservations

ofincreasesinglobalaverageairandoceantemperatures,widespreadmeltingofsnowandiceand

risingglobalaveragesealevel1.Globalgreenhousegas(GHG)emissionsduetohumanactivitieshave

grownsincepre‐industrialtimes,withanincreaseof70%between1970and2004,andmostofthe

observedincreaseinglobalaveragetemperaturessincethemid‐20thcenturyisconsideredverylikely

1IPPC,2007.ClimateChange2007:SynthesisReport.ContributionofWorkingGroupsI,IIandIIItotheFourth

AssessmentReportoftheIntergovernmentalPanelonClimateChange [CoreWritingTeam,Pachauri,R.K.andReisinger,A.(eds.)].IPCC,Geneva,Switzerland,104pp.



duetotheobservedincreaseinanthropogenicGHGconcentrations1.Discerniblehumaninfluences

alsoextendbeyondaveragetemperaturetootheraspectsofclimate.Carbondioxide(CO 2)isthe

mostimportantanthropogenicGHG.

Tomitigateforecastdestructiveclimatechangeconsequenttofurtherglobalwarming,

anthropogenicGHGemissionsmustbestabilisedandreduced.Thisisaglobalchallengetobe

addressedbyallcountrieswithconsiderationofallsignificantemissionsources.For2007,shipping

wasestimatedtohaveemitted3.3%ofglobalCO 2emissions,towhichinternationalshipping

contributed2.7%,or870milliontonnes2.Althoughinternationalshippingisthemostcarbon

efficientmodeofcommercialtransport,totalemissionsarecomparabletothoseofthe6thlargest

nationGHGemitter,necessitatingemissionreduction3.Moreover,accordingtotheIMO’sGHGStudy

(2009)ifunabated,shipping’scontributiontoGHGemissionscouldreach18%by2050.

TheShippingefficiency.orgRating

Shippingefficiency.orgprovidesafree‐access,betaandcomprehensiveassessmentofanominated

vessel’seco‐efficiencycredentials.TheEEDIassessmenthasan”AtoG”rating,basedonanalysisof

datafromIHSFairplayandprocessedandformulatedbyRightship.

AspartofitsstrategytoaddressCO 2emissionsfromships,IMOMEPChasdevelopedtwoarithmetic

measuresoftheenergyefficiencyofindividualships:theEnergyEfficiencyDesignIndex(EEDI),and

theEnergyEfficiencyOperationalIndicator(EEOI).TheShippingefficiency.orgAtoGratingisbased

oncalculationandanalysisoftheEEDI.

EnergyEfficiencyDesignIndex

TheEEDIwasdevelopedasameasureoftheCO 2emissionperformanceof,primarily,newshipsand

iscalculatedfromdataontheshipdesignandengineperformance.Theintendedapplicationofthis

indexwastostimulateinnovationandtechnicaldevelopmentofallelementsinfluencingtheenergy

efficiencyofashipfromitsdesignphase.TheEEDIiscalculatedbythefollowingformula4:

2IMO,2009.SecondIMOGHGStudy2009.InternationalMaritimeOrganization(IMO)London,UK.

3ICS,2009.Shipping,WorldTradeandtheReductionofCO2Emissions.InternationalChamberofShipping,

London,UK.

4

IMO,2009.InterimGuidelinesontheMethodofCalculationoftheEnergyEfficiencyDesignIndexforNewShips.CircularMEPC.1/Circ.681.InternationalMaritimeOrganization,London,UK.



inwhich:

MEandAE,representMainEngine(s)andAuxiliaryEngine(s);

P,thepoweroftheengines(kW);

C F ,aconversionfactorbetweenfuelconsumptionandCO 2basedonfuelcarboncontent;

SFC,thecertifiedspecificfuelconsumptionoftheengines(g/kWh);

Capacity ,thedeadweightorgrosstonnage(tonnes);

V ref ,theshipspeed(nm/h);and

f j ,acorrectionfactortoaccountforshipspecificdesignelements(e.g.ice‐class)

ThecalculatedEEDIisatheoreticalmeasureofthemassofCO 2emittedperunitoftransportwork(g

CO2/tonne.nm)foraparticularshipdesign.

Shippingefficiency.orgGHGRatingCalculation

DataSources

EEDIvaluesarecalculatedfromdataonshipcharacteristicsandperformanceaccessibleto

Shippingefficiency.org.TodatetheprimarysourcesofdatahavebeenexistingdatawithinSVIS©,

Lloyd’sRegisterFairplay(LRFP)database,andownersdata,butthiswillbesupplantedbyship‐

sourceddataasitbecomesavailable.Weencouragethewebsiteuserstoinputtheirdata.

Assumptions

Whereshipspecificdataarenotavailable(e.g.specificfuelconsumption),thevaluesusedinthe

Shippingefficiency.orgcalculationofEEDIarebasedonthesameassumptionsusedintheIMOGHG

Study2and/ordetailedintheIMOCircularoncalculationoftheenergyefficiencymeasure

4,.

Theseassumptionsare:

• SpecificFuelConsumption(MainEngine), SFC ME :

EngineAge MCRME

(kW)SFCME

(g/kWh)

>15,000 205

5,000to15,000 215Pre‐1983

<5000 225

>15,000 1851984‐2000

5,000to15,000 195



<5000 205

>15,000 175

5,000to15,000 1852001‐2007

<5000 195

• SpecificFuelConsumption(AuxiliaryEngine), SFC AE :

EngineAge MCRAE>800kW MCRAE<800kW

Any 220g/kWh 230g/kWh

• Power(MainEngine),PME : =0.75MCRME

• Power(AuxiliaryEngine),P AE :

MCRME >10,000kW <10,000kW

P AE =(0.025*MCRME )+250 0.05*MCRME

• ShipSpeed,V ref : =DesignSpeed

• Capacity :

o Deadweight,fordrycargocarriers,tankers,gastankers,ro‐rocargoandgeneral

cargoships

o 65%deadweight,forcontainerships

o Grosstonnageforpassengershipsandro‐ropassengerships

• CO2ConversionFactors,C F :

FuelTypeCarbonContent

C F

(t‐CO2/t‐Fuel)

Diesel/GasOil(DGO) 0.875 3.206

LightFuelOil(LFO) 0.86 3.15104

HeavyFuelOil(HFO) 0.85 3.1144

LiquifiedPetroleumGas(LPG)

Propane 0.819 3.000



Butane 0.827 3.030

LiquifiedNaturalGas(LNG) 0.75 2.750

ShipTypesandSizes

ThecategoriesofshipandshipsizesusedforthederivationofcomparativeGHGratingsfollowthose

inIMOdocumentMEPC61/WP.105asfollows:

.1 Passengership

.2 Drycargocarrier

.3 Gastanker

.4a Tanker:Chemical

.4b Tanker:Oil6

.5 Containership

.6 Ro‐rocargoship:Vehiclecarrier

.7 Ro‐rocargoship:Volumecarrier

.8 Ro‐rocargoship:Weightcarrier

.9 Generalcargoship

.9bis Refrigeratedcargoship

.10 Ro‐ropassengership

RatingCalculation

TheEEDIratingsforanindividualshiparecalculatedbyassessingthevaluesforthatshiptooverall

averagevaluesforallshipsofthattype(e.g.bulkcarriers)andtoothershipsofasimilarsizewithin

thistype.Thesizecomparisonistothe50,100or200shipswithinthetypethatareclosestin

capacity(dwt,gt,teuorcbm)totheindividualship(i.e.if100ships,the50shipsinthedatabase

withdwt/gt/teu/cbmclosestto,butlessthantheship,andthe50withdwt/gt/teu/cbmclosestto

butgreaterthantheship).Thenumberofshipschosenforcomparisonisbasedonthenumberof

shipsofthetypeinthedatabaseandtheirsizedistribution.

5IMO,2010.ReportoftheWorkingGrouponEnergyEfficiencyMeasuresforShips,Annex2.Guidelinesfor

calculationofreferencelinesforusewiththeEnergyEfficiencyDesignIndex.PaperMEPC61/WP.10Annex2.

InternationalMaritimeOrganization,London,UK.

6IncludesCombinationCarriers(OBOs)



The‘AtoG”ratingreflectsacomparisontovesselsofsimilarsizewithinatype.The

Shippingefficiency.orgAtoGratingisbasedontheEEDI(Size)Rating(detailedlater),whichindicates

thenumberofstandarddeviationsavesselvariesfromtheaverageforsimilarlysizedvesselsofthe

sameshiptype:

A B C D E F G

>2.0 >1.0 >0.5 >‐0.5 >‐1.0 >‐2.0 <‐2.0

IfthedistributionoflogtransformedEEDIvaluesexactlyfittedanormaldistribution,thescore

rangeswouldmatchfixedpercentilesofthedataset;i.e.<‐2=0to2.5%,<‐1=2.5to16%,<‐0.5=16

to32%,<0.5=32to68%,<1.0=68to84%,<2.0=84to97.5%and>2.0=97.5to100%.However

eachvesselsizegroupisasamplegroupandpercentageswithinasizegroupwillhavesome

variabilityfromthesepercentagesandareonlyindicative.

EEDIvaluesaretransformedbeforestatisticalcomparisontoovercomethestronglyskewed

distributionoftherawdata.Asanexample,thefrequencyofoccurrenceofEEDIvaluesforbulk

carriersispresentedinFigure1.Thedistributionofvaluesforallshipsisseentonotfitanormal

(bell‐shaped)curve,withtheaverageofallvaluesnotcentraltothedistribution.Directcomparison

ofindividualshipvaluestotheaveragevaluewouldtherforehaveabiasagainstaboveaverage

(generallysmaller)ships,bothfortheoveralltypeandwithinshipsizecategorieswithinthetype.

Figure1.Frequencydistributionofcalculatedvaluesforallbulkcarriersinthedatabase,andtwosize

categories:sizeD(35–60,000dwt)andsizeF(<10,000dwt)



ApplyingalogarithmictransformationtothecalculatedEEDIvaluesnormalisesthefrequency

distributionforboththeoverallshiptypeandshipsizecategorieswithintheshiptype(Figure2).

Thisenablesindividualshipvaluestobevalidlycomparedtotheaverageforshiptypeorsize.

Figure2.Frequencydistributionoflogarithmic(ln)transformedEEDIvaluesforallbulkcarriersinthe

database,andtwosizecategories:sizeD(35–60,000dwt)andsizeF(<10,000dwt)

Themethodforcomparinganindividualship’sEEDIvaluetothetypeorsizecategory,andtoderive

theEEDIratingsreportedintheShippingefficiency.orgAtoGrating,isbasedoncalculatinga

statisticalz‐score.Az‐scoreisastandardmeasureofthevariationofanindividualvaluefromthe

average,andiscalculatedbydividingthedifferencebetweentheshipvalueandtheoverallaverage

forthetypeorsizegroupbythestandarddeviationforthetypeorsizegroup.

zscore=(yi–ŷ)/s

where:

yiistheshiplnEEDIvalue,

ŷistheaverageoflnEEDIvaluesforthetypeorsizegroup

sisthestandarddeviationofthelnEEDIvaluedistributionforthetypeor

sizegroup

Azscoreisastandardizedvaluethatrepresentsthevalueofthevariablefromanormaldistribution

withameanofzeroandastandarddeviationofone.Zscorescanthereforebecomparedacross

datasetswithdifferentvaluescoresandranges.

ForthepurposeoftheShippingefficiency.orgGHGrating,thenegativezscoreisused;i.e.thesign,

positiveornegative,ofthecalculatedzscoreisreversed.Thisisdonebecausethezscorecalculation



willgivepositivenumbersforvaluesabovetheaverage(i.e.highEEDI)andnegativenumbersfor

valuesbelowtheaverage(i.e.lowEEDI).BecauselowEEDIvaluesrepresentbetterenergyefficiency,

assigningapositivevaluetothescoreisconsideredtobetterrepresentgoodperformance.

TheGHGRatingfortheEEDIisachievedbytheadditionoftwoscores:thezscoredetermined

relativetothesizeclass(“(Size)Rating”),addedtothezscoredeterminedrelativetotheoverallship

type(“(Type)Rating”).

GHGRating =‐zscoreType+‐zscoreSize

Theincorporationofthetwocomponentsisconsideredimportantbecauseitconsidersboththe

efficiencyoftheshiprelativetoothershipsofthesametypeandsimilarsize,andtheefficiency

withinthetypeoverall.Bydesign,theEEDIgenerallyreturnslowernumbers,indicatingbetter

efficiency,forlargercapacityshipsbecausetheamountofCO 2emittedperunitoftransportwork

dropsasshipsizeincreases.Thisisbecausetheenginepower/fuelconsumptionandcargocapacity

donotincreaseina1:1ratio.Althoughinmostsituationscomparisonswillbebetweenshipsofsimilarsizes,itisimportanttoalsoreflectthevaryingefficiencybetweendifferentsizeclasses.

AgainusingtheEEDIcalculationsforbulkcarriersasanexample,Figure3isascattergramofEEDI

(Size)Ratingsagainstshipsize,Figure4ofEEDI(Type)Ratingsagainstshipsize,andFigure5ofEEDI

Ratingagainstshipsize.

Figure3.ScattergramofEEDISizeRatingsagainstShipSizeforallbulkcarriersinthedatabase



Figure4.ScattergramofEEDITypeRatingsagainstShipSizeforallbulkcarriersinthedatabase

Figure5.ScattergramofEEDIRatingsagainstShipSizeforallbulkcarriersinthedatabase

Whatthesefiguresshowisthat,forthesizerating(Figure3),thereisarelativelyevenspreadof

EEDIaboveandbelowzeroacrossallsizes,whereasforthetyperatingmostsmallships(<50,000t)

havenegativeratingsandalllargeships(>100,000t)haveapositiverating.Combiningthetwointo

atotalrating(Figure5)resultsinamoreevendistributionwithmoresmallshipsstillwithanegative

rating,andmorelargeshipsstillwithapositiverating,butwithpositiveandnegativeratingsevident

acrossalmostthefullsizerange.



DataPresentation

TheShippingefficiency.orgRatingforanindividualshipispresentedinasnapshotgraphicshowing

therelativevalueoftheEEDIintheAtoGRatingscale(Figure6).Adetailedtableisalsoprovided

whichincludesdatausedincalculations,thestandardEEDIvalue,andcriticalnumbersusedinthe

calculationoftheshipGHGRating.

Figure6.ExampleoftheGHGAtoGRatingsnapshotforanindividualship

RatingDatabase

TheShippingefficiency.orgRatinghasbeencalculatedandanalysedacrosssevenofthemajorship

typeswiththenumberofcalculatedvaluesofEEDIforeachselectedmajorshiptypeasfollows:

ShipType EEDI

CrudeOilTankers ~2,900

ProductTankers ~7,300

ChemicalTankers ~1,300

LPGTankers ~1,300

LNGTankers ~350



BulkCarriers ~11,000

GeneralCargo ~15,000

Containerships ~5,800

VehicleCarriers ~980

CruiseShips ~390

ScattergramsofthecalculatedEEDIvaluesforeachoftheseshiptypesagainstcapacity(dwt,cbm,

orteu)showtheEEDI/capacityrelationshiptobebestrepresentedbyapowerregressionline,as

recognisedbyIMOMEPCintheirestablishmentofanEEDI“referenceline”fornewships.Detailed

analysisoftheGHGRatingsacrossshiptypeshasshownthatthemethodusedtodevelopa

comparativeratingofEEDIRatings,asacomponentoftheShippingefficiency.orgEnvironmentalRating,isapplicabletoalloftheseshiptypes.Themethodthereforeprovidesameansofcomparing

theenergyefficiencyofexistingships.

However,itisimportanttonotethatthereliabilityofthecalculatedratingsisadirectfunctionofthe

reliabilityofthesourcedata.AnongoingpriorityofShippingefficiency.orgistoeitherverifybase

dataorsourceaccuratedata,andthiswillbeusedtocontinuallyupgradeandenhancethe

environmentalratingsystem.

Eedi Methodology

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