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8/3/2019 2 Sabol Cost Estimating
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ChallengesinCostEstimating
withBuildingInformation
Modeling
LouiseSabol
Contents
Overview
BIM,CostEstimatesandProjectPhasing
SupportingInformationExchangeBIM
and
Costing
Applications
StandardizingDataModelsand
Definitions
BuildingInformationModelsforthe
ProjectLifecycle
Conclusion
References
Abstract
Asavisualdatabaseofbuildingcomponents,BIMcan
provideaccurateandautomatedquantification,andassistin
significantlyreducingvariabilityincostestimates.
ExchangingdataisachallengingaspectofAECinformation
technology.BIMapplicationsareevolvingandstandard
formatstoorganizeandsharebuildinginformationarefar
fromfullymatureaswell.
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Overview
BuildingInformationModeling(BIM)offersapotentiallytransformationaltechnologythroughits
capabilitytoprovideashareddigitalresourceforallparticipantsinabuildingslifecyclemanagement,
frompreliminarydesignthroughfacilitiesmanagement.Asavisualdatabaseofbuildingcomponents,
BIMcanprovideaccurateandautomatedquantification,andassistinsignificantlyreducingvariabilityin
costestimates.
ExchangingdataisachallengingaspectofAECinformationtechnology.BIMapplicationsareevolving
andstandardformatstoorganizeandsharebuildinginformationarefarfromfullymatureaswell.
SoftwareapplicationscanemployseveralmethodsforexchangingdataXML,APIs,ODBCamongthem.
Themethoduseddependsonthephaseoftheproject,detailrequired,andtypeofinteractionneeded
betweenBIMandanexternalapplication.
CostingexercisescanbeconductedthroughouttheprojectlifecyclewithBIM.Thelevelofdetailinthe
modelwillvarydependingontheprojectphase.FirmsemployingBIMwillneedtodevelopmethodsand
standardsforobjectdevelopmentthatsupportthelevelofdetailrequiredforusefulestimates,aswell
asprovideaframeworkforprovidingconsistentinformationfortheBIMcomponentstalliedbycost
estimators.
Figure1:Traditionalcostestimatingtakeoffvs.BIMbasedquantification1
BIM,CostEstimatesandProjectPhasing
Costestimationforbuildingprojectstraditionallystartswithquantificationatimeintensiveprocessof
tallyingcomponentsfromprinteddrawingsets,ormorerecently CADdrawings.Fromthesequantities,
estimatorsutilizemethodsfromspreadsheetstocostingapplicationstoproducetheprojectcost
estimate.Thisprocessispronetohumanerrorandtendstopropagateinaccuraciesthatcreepintothe
tallies.Currently,quantificationisalsotimeconsumingitcanrequire50%to80%ofacostestimators
timeon
aproject.
2
BIMoffersthecapabilitytogeneratetakeoffs,countsandmeasurementsdirectlyfromamodel.This
providesaprocesswhereinformationstaysconsistentthroughouttheprojectandchangescanbe
readilyaccommodated.Buildinginformationmodelingsupportsthefullprojectlifecycleandoffersthe
capabilitytointegratecostingeffortsthroughoutallprojectphases.Theinformationinamodelandtype
1ScreenshotfromUSCostsSuccessApplicationandAutodeskRevit.2123Revit:BIMandCostEstimating,RickRundell,CadalystMagazine,AugustandSeptember2006.
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ofcostestimateneededdependsonthephaseoftheprojectrangingfromhighlevelschematic
modelsduringpreliminaryphases,todetailedestimatesasprojectsenterconstruction.
PreliminaryCostEstimates
Duringtraditional(e.g.manual)projectdevelopment,accurate,actionablecostinginformationhasbeen
difficultto
define
during
preliminary
project
phases.
Greater
project
efficiencies
and
more
accurate
schedulingcanbedevelopedbasedonrealisticcostingfeedbackearlyon.
Architectstypicallydonotprovidecostestimatesonprojectsaspartoftheirstandardservices,butthe
nativecapabilityofBIMtoquantifyandcalculateischangingthenatureofprojectdeliverablesforall
participants.Conceptualortopdownestimatesarethefirstseriousefforttopredictthecostofa
projectandaligndecisionmakingwiththoseestimates.Projectinformationattheseearlystagesis
usuallygeneralandatahighlevel(e.g.numberofoccupants,grosssquarefeetarea,andenclosed
volume).
Preliminarycostingisgenerallybasedontemplatesfrompastprojectexperience,oronstandardsquare
footcostsbasedonprojecttype,region,ortypeofconstruction.Preliminaryestimates,unlikethose
createdduringlaterstages,arepreparedusingconcepts(e.g.hospitalscost$x/sq.ft.orcorporate
spacestandards
require
xsq.
ft.
for
this
project),
and
avoid
counting
of
individual
pieces.
Figure2:ProjectandCostEstimatingProcess
StandardCAD,andnowBIM,applicationshavethecapabilityofmodelingdatafarinexcessofwhatis
neededatpreliminaryprojectphases.Detailedmodelingcanconfusedecisionmakingandscenario
planningratherthanassistit.Determiningwhatthebuildinginformationmodelisduringtheplanning
andschematicphasesofaprojectinvolvesdelineatingwhatinformationisrequiredtosupportthe
decisionmaking
processes
at
the
early
stages
of
aproject.
SchematicBIMmodelsarebasedonsimplegeometriesandneedtobeflexibleandlightweightenough
tosupportmanyiterationsandchangesinherentinearlyprojectphases.Modelsatthisprojectstage
aregeneratedfromfunctionalrulesandprogrammaticrequirementsratherthangeometryand
specifications.Standardobjectsorassemblies(cellsorblocksinCAD)atthisphasearegenericand
lessdetailedinnaturetobereplacedlaterintheprojectastheprojectdevelopsthroughdesign
developmentandconstructiondocumentphases.
ConceptualPhase
Project/BIM
Development
PreliminaryEstimateEstimate
Design/Engineering
Fair CostEstimate
Construction
DefinitiveEstimate
Value Engineering
Fair CostEstimate
DefinitiveEstimateDefinitiveEstimate
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Softwareapplicationsthatdeveloppreliminarybuildingmodelsandcostingestimatesmaynot
necessarilybethesametoolsusedtosupportthedesigndevelopmentanddocumentationprocesses
thatfollow(moretypicallythoughtofasBIM).Thesameprocesschangethatoccursnowduring
projectdevelopmentwillstillexistinfullyautomatedprojects,butimproveddecisionsupporttoolsare
beingdevelopedtoassistprojectprofessionalsearlieron.Preliminaryapplicationsshouldhavethe
capabilitytoexportdevelopedinformationtofullfledgedBIMmodelers.
DetailedCostEstimates
Detailedestimates,alsoknownasbottomup,faircost,orbidestimates,arepreparedfromwelldefined
designandengineeringdata.Theseestimatesaregenerallycarriedoutforbidevaluations,contract
changes,workscoping,permitsandapprovals.Asprojectdevelopmentprogressesfromschematic
designthroughcontractdocuments,quantificationandcostingbecomedependentondeveloping
objectsinthebuildingmodelinincreasinglevelsofdetailandcomplexity.
Figure3:CostEstimatingClassificationMatrix3
ThelevelofdetailencapsulatedwithinaBIMobjectisajudgmentarea.BIMimplementersneedto
developstandardsforrepresentingbuildingelements(objects,families,assemblies)inamodelto
whatlevelofdetail,atwhatphaseoftheproject.Elementscanbemodeledingenericfashion(e.g.
FlushDoor)ortoawelldefinedlevelofdetail(e.g.5PlyParticleCoreWDMAExtraHeavyDutyPC5
FlushDoor).AECprofessionalsneedtodevelopgraphicrepresentationsdetailedenoughtosupport
theirdocumentationeffort,withoutcreatingaBIMmodelthatistoocumbersome(heavy)toupdate
andcoordinate.
Objectsand
assemblies
can
be
encoded
with
data
in
abuilding
information
model
to
some
extent.
Additionalinformationcanbeaffiliatedwithobjectsinanexternaldatabaseaswell.Costingapplications
harvestinformationfromBIMobjectsinvariousmannerseitherenhancingobjectdefinitionswithin
themodel,orusingauniqueidentifiertolinkobjectstomoredetailedinformationstoredexternally
fromtheBIMapplicationinadatabasesuchasMicrosoftAccessorOracle.
3AdaptedfromAACERecommendedPracticeNo.17R97:CostEstimateClassificationSystem,AACE,Inc.,1997.
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Costingeffortsrequireamechanismtocullcomponentinformationfromthebuildingmodelforeach
iteminthemodel identifyinginformationandquantities,andexportingthisdatatoacosting
application.MechanismstoexportinformationfromBIMapplicationsarediscussedinthefollowing
section.Ideally,theexchangeofdatabetweentheBIMandcostingapplicationswouldbebidirectional,
allowingevolvingdesignmodelstoretrieveinformationfromcostingexercisesthatresultintheneed
foralternativesandsubstitutions.Currently,automatedBIMcostingapplicationsdonotaccommodate
bidirectionality.
Valueengineeringefforts,typicallyundertakenduringtheconstructiondocumentationphase,would
greatlybenefitfromthecapabilitytoautomatesubstitutionsinthebuildingmodelfromcosting
analyses.BIMcostingexercisesthroughouttheprojecthavethepromiseofreducingtheneedforvalue
engineeringbysupportingthedecisionmakingprocesswithmoreaccurateinformation,earlierinthe
project.
SupportingInformationExchangeBIMandCostingApplications
Buildinginformationmodelingoffersthepromiseofacommoninformationrepositoryforallproject
participants.MultiplepartiescantapintoaprojectBIMtoderivecomponentinformationforarangeof
taskssuch
as
environmental
compliance,
energy
analysis,
as
well
as
materials
take
off
and
project
costing.Severalstandardsoftwaremethodsareusedbyapplicationsdeveloperstofacilitatethis
informationexchangebetweenBIMmodelsandexternalbuildinganalysisapplications.
ApplicationProgramInterface
AnApplicationProgramInterface(API)isasetofroutines,protocols,andtoolsforbuildingsoftware
applications.SoftwarevendorsprovideAPIstogivethirdpartydevelopersthebuildingblocksto
developaddonapplications.APIsareonemechanismthatcanbeusedtoexportinformationfrom
withinaBIMapplicationforusebycostingapplications.
APIroutinesallowcostingapplicationstotrackthestatusofobjectsimportedfromaBIMmodel.This
allowsuserstodeterminewhetheritemsorassemblieshavebeenupdatedsincetheywerelast
imported,andupdatecostsaccordingly.
Atpresent,somedevelopersarecautiousaboutusingAPItoolkitsforapplicationssinceBIMsoftware
hasbeenundergoingupgradesanddevelopmentatarapidpace(ergo,APIsarebeingenhancedand
changedregularly,requiringdeveloperstoupgradesoftwarebasedonAPIinterchangemorerapidly
thanothermediumssuchasODBCorIFCs).
OpenDatabaseConnectivity
TheOpenDatabaseConnectivity(ODBC)formatisastandarddatabaseaccessmethoddevelopedby
Microsoft.Widelyaccepted,ODBCcanbeconsideredatypeofAPI,offeringavendorneutral
mechanismforexchangingdatabetweenanapplicationsuchasBIMandarelationaldatabase(RDBMS).
ODBCinserts
amiddle
layer,
called
adatabase
driver,
between
acalling
application
(BIM)
and
the
databaseapplication,whichtranslatestheBIMapplication'sdataqueriesintocommandsthatthe
RDBMSunderstands.ThegoalofODBCistoenableaccesstodatafromanyapplicationBIMorothers,
regardlessofthedatabasemanagementsystemused.
ODBCofferstheadvantageofnotrequiringanyspecialprogrammingorinterfaces,aslongasthecalling
applicationandthedatabasesoftwaresupportODBC.Thissimplifiesandreducesthecomplexityof
encodingdatalinkstoBIMelements.StoringdataexternallyfromtheBIMapplicationskeepsthemodel
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lightweightandallowsamoreexpeditiousaccesstoexternalapplications likecostestimating,that
needtousethatinformation.
ODBCislimitedbythefactthatthereisnorealtimesynchronizationbetweenanapplicationsuchas
BIMandthedatabase(i.e.theyarenottightlywrapped).Theusermustexplicitlyrunacommandto
exportdatafromtheBIMapplicationtothedatabase.ThedatabasehasnocontrolovertheBIM(i.e.
changesin
the
database
cannot
drive
changes
in
the
building
model).
StandardizingDataModelsandDefinitions
Aprerequisitetothesuccessofcostestimatingwillbeconsistentdefinitionsanddataformatsfor
buildingobjectsandassemblies.Therearesignificanteffortsunderwaytodevelopconsistent
frameworksfordatainteroperabilityintheAECFMindustry,provingcommondefinitionsinacommon
formatforthemanyparticipantsthroughoutthebuildingprocess.
IndustryFoundationClasses
TheIndustryFoundationClass(IFC)isadatamodeldevelopedbytheInternationalAlliancefor
Interoperability(IAI).Itaimstoprovideasingle,internationallyacceptedframeworktofacilitate
informationexchangeamongparticipantsinthebuildingprocess,throughouttheentirelifecycle.
ThecapabilitiesofbuildinginformationmodelsextendwellbeyondprevioustechnologiesofCADand
generic3Dmodelswhichwerepurelygeometricinnature.Geometryisjustoneofthepropertiesof
buildingentities,butitservesastheprimaryinterfacetointeractwithabuildingdatabaseinBIM.
Buildinginformationmodelstrackinformationonallofthecomponentsthatcompriseabuilding,and
canrangefromtheverygenerictothefullydetailed.
Figure4:CAD(Geometric)vs.BIMElementDescription
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TheIFCconceptisawellregardedcollaborationfacedwithacomplexgoal.Theeffortisbeing
developedbyanallvolunteerorganizationforahighlyheterogeneousindustry.Atpresent,BIM
softwarevendorshaveintegratedIFCexporterswithintheirapplications,butthemajorsuccessofthese
exportsiswiththe3Dgraphicelements.IFCexportinghaslesssuccesstodateexchangingnongraphical
properties,complexgeometries,orparametricallymodeledcomponents.
IFCsmay
never
become
the
standalone
unifying
model
or
translation
medium
for
BIM.
However,
they
mayhavethegreatestpotentialforstandardizingBIMdataexchangebyprovidingacommonsetof
termsanddefinitions.IFCsofferaframeworkfordatadescription,buttherewillnotbeanofftheshelf
coverageofallthecomponentsneededforadetailedcostestimateinallcases.TheusefulnessofIFCs
maybeextendedbybeingusedinconjunctionwithmorecustomizeddatastructuresandexchange
formatsforspecificpurposes,includingcostestimating.Atpresent,commercialcostestimating
applicationsutilizeIFCs,butnotasthesolechannelforinformationexport.
ExtensibleMarkupLanguage
AmoregeneralmeansofexchangingelectronicinformationisofferedthroughtheExtensibleMarkup
Language(XML)format.Thisisatextbased,platformneutralsupersetofwebsoriginalHyperText
MarkupLanguage
(HTML).
Whereas
IFCs
provide
awell
structured
and
detailed
framework
for
building
information,XMLisamoregeneralmeansofformattinginformationthatistobepassedfromone
applicationtoanother.
OneexampleofXMLsuseinaBIMapplicationistoexportquantitytakeoffinformationtoa
spreadsheetapplication.TheXMLformatisusedasanexchangemediumforarangeofbuildingrelated
schemas.AfewoftheseincludegbXML(greenbuilding),AGCxml(constructionrelateddata)and
CityGML(urban3dmodels).BIMdatathatisinIFCformatcanbeexportedviaanXMLframework,but
theresultingfilestendtogetverylarge perhapsprohibitivelyso(asshownintheexampleofasmall
pieceofcodebelow).
Figure5:IFCdefinitionandifcXMLschema4
StandardTaxonomies
4Adaptedfrom:ifcXMLImplementationGuide,N.Nisbet,T.Liebiched.;February9,2005
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Developinganautomatedcostestimateisdependentonusingaconsistentframeworktoorganizethe
manycomponentsthatconstituteabuilding.Severaltaxonomies techniquesofclassification,have
beenusedforyearsintheAECprofessiontoorganizebuildinginformation.Methodschosenforuseare
verydependentontheprojectphaseanddetailrequired.Preliminaryphasesrequireamuchmore
generalizedorganizationthanthedetailedinformationrequiredduringthematurephasesofaproject
cycle.
Figure6:ConstructionInformationStandardsbyPhase5
UniFormatwasdevelopedintheearlyseventiesandenhancedin1993(byCSI,GSA,AACE,R.S.Means
andothers)toorganizeinformationforestimatinganddesigncostinganalysisbyaprojectsmajor
components.Thisframeworkbreaksbuildingsystemsintocategoriessuchasfoundation,
superstructure,shell,andinteriorconstruction,andintosubcategories suchasfloorandroof
constructionandexteriorwallsandwindows.Theformatisusefultocostestimatesbeinggeneratedin
thepreliminaryphasesofaproject.BIMapplications,suchasRevit,useUniFormatfororganizingtheir
objectsandassemblies.Theformat,byitself,willbetoogeneraltocategorizecomponentsfordetailed
cost
estimates
(Figure
7).
MasterFormatisaspecificationswritingstandarddevelopedbytheConstructionSpecificationsInstitute
(CSI)andhasbeeninuseforoverfortyyears.Thisstandardorganizesinformationbyconstruction
requirements,productsandactivities(termedworkresults).Thisframeworkisgenerallyusedduring
theconstructiondocumentationphasesofabuildingproject,whendetailedinformationisdeveloped
andorganized.
5Adaptedfrom:CSIFormatsandBuildingInformationModeling,RogerGrant/CSIforFederalFacilitiesCouncil,
Forum,October31,2006
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Figure7:WalldetailandclassificationbyUniFormatandMasterFormat
OmniClass(OCCS)isanewlydevelopedAECindustrywideinitiativeledbytheConstruction
SpecificationsInstitute(CSI)andendorsedbytheIAI.Itisintendedtobethemostcomprehensive
classificationformat,essentiallyclassifyingtheentirebuiltenvironmentfortheNorthAmericanmarket.
PortionsoftheMasterFormat(forworkresults),UniFormat(forelements)andEPICElectronicProduct
InformationCooperation(forproduct)systemshavebeenadaptedintothisframework.
OmniClassestablishesaterminologylibrarythatcanbeusedtoexplicitlyidentifyobjectsandtheirparts
byassociatingtheirnameswiththeactionsandresourcesthatmakethemup.Inthepracticeofbuilding
informationmodeling,objectsthatareassociatedwithtermsinanOmniClasslibrary,inheritstandard
setsofpropertiesandpredefinedrelationshipswithotherconceptsintheOmniClassdefinition
framework,bythisassociation.
BuildingInformationModelsfortheProjectLifecycle
BuildingInformation
Modeling
offers
the
promise
of
acommon
repository
for
building
information
for
allprojectparticipants.Asanevolvingtechnology,itremainstobeseenwhetherBIMwillconsistofone
consolidatedmodeloraconfigurationofdistributed,yetsomehowaffiliated,datamodels.TheAEC
industryisstillahighlysegmentedbusiness;participantshavedifferentfunctionalrequirements,
deliverablesvaryindetailandpurpose,andavailabletechnologiesandstandardsarestillevolving.
Incurrentpractice,differentBIMmodelsareoftendevelopedfordifferentpurposes,fromplanningto
fabrication.Aschematicmodelusedforpreliminarycostingwillbemoreofamassingorstackand
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blockmodel,withoutdetailedcomponentdefinition.BIMmodelswillneedtobelightenoughtobe
responsiveduringprojectdevelopmentandgenericenoughtofacilitatechange.Somecommercially
availablesoftwaredevelopersareaddressingconceptualcostestimating,notablyTrelligencesAffinity
andBecksDprofilerapplications.
Figure8:
Preliminary
costing
applications
Trelligence
Affinity
(left)
and
Beck
Dprofiler
(right)
Modelsdevelopedtosupportonephaseofthelifecyclewillneedtobepassedalongtothenext,
requiringtheBIMuserbasetoclearlydelineatetheirprocessesanddevelopguidelinesandstandards
(e.g.WhatinformationisincludedinaBIMmodelateachphase?Whendogenericobjectsinamodel
getreplacedbymoredetailedobjects?Atwhatstagearecostestimatesdoneandwhatisincludedin
theproduct?Whohastheresponsibilitiesintheprocessfordoingandoverseeingtheseactivities?).
BIMdevelopmentprocessesneedtosupportthedifferentusesofthemodelindifferentprojectphases.
Thiscanbeaccommodatedwiththeuseofmultipleobjectlibrariesforincreasinglevelsofdetail.For
example howcostscalculationsarederivedfromwallsduringthecourseofaprojectwillvary.
Estimatesduring
earlier
phases
will
use
amore
generalized
cost
per
linear
foot
for
acertain
wall
type.
Forthatsamewall,however,constructorswillneedtoderiveatotalareaforgypsumboard,doublearea
forfinishes,framing,basemoldingandnailquantity.Accuracyofcostestimatingwilldependdirectlyon
howwelldevelopedassembliesandobjectsareinthemodel.
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Figure9:Objectdataforagenericwindow(left)andanAndersonWindow(right)6
MoresophisticatedapplicationsarebeingdevelopedtoenhancetheBIMprocessfordataintensiveusessuchascostestimating,environmentalcompliance,energyanalysis,andcomponentfabrication.
Howcomponentdata,suchascostsandspecifications,istobeassociatedwithBIMcomponentsisa
significantissueinrightsizingaBIMmodelscomplexity(e.g.WhatdataisstoredintheBIMmodel?Is
anexternaldatabasebeingusedforstoringdetaileddata,andifso howisthatdatastructuredand
exchanged?).
Duringprojectdevelopment,objectsinaBIMmodelneedtobepopulatedwithsufficientdatatoallowa
costingapplicationtoaccuratelyclassifythematerialsandassigncosts.Developingdetaileddefinitions
forcostingcantakeseveralpaths.Largefirmsororganizations,suchastheUSCorpsofEngineers
(USACE),candevelopdetailedinhousestandardsforassembliesthatcompriseitsbuildingmodels.
USACEiscreatingadetailedIFCbasedformattobeassociatedwithobjectsinamodel(enhancingthe
baseIFCdefinitionswiththedetailrequiredforstandardcomponentsusedintheirprojects).
CommercialBIMcostestimatingapplicationsworkinvariouswaystoenhancethedetailassociatedwith
aBIMobjectinordertogeneratecostestimates,oftenenhancingobjecttagsortextfieldswithdetailed
assemblyormaterialdescriptions.LightweightmodelsexportedfromtheprimaryBIMapplications
areusefulforarangeofpurposes,severalcurrentusesinclude:NavisWorksimportsBIMmodelstoits
ownformatstructureforclashdetectionandscheduling;Innovayaemploysalightweightmodelformat
tosupportitsvisualestimatingapplication;AutodeskofferstheDWFformatfordesignreview;and
SolibriimportsIFCmodelsforrulesbasedanalysis.
Monolithic,doeverythingsystemshaveyettobeasilverbulletinanyarena.Newinformation
technologiesingeneral,suchasWeb2.0,ServicesOrientedArchitecture,etal,areevolvingtosupport
integrationand
collaboration
between
applications
through
interoperability,
aiming
to
ease
the
flow
of
informationbetweensilos.
6fromAutodeskRevit2008
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BidirectionalUpdating
ThecapabilityforBIMgeneratedcostestimatingapplicationstoupdateandchangetheoriginalbuilding
modelremainsundeveloped.Costingexercisesoftenresultintheneedtosubstitutecomponentsofthe
buildingdesign.Costingapplicationshaventyetdevelopedthefacilitiestoexportthesedecisionsback
toBIMandautomaticallyupdatethebuildingmodeltoreflectthechanges.Currentcostingapplications
dohave
the
ability
to
flag
items
that
have
either
changed,
or
have
been
added
to
the
original
model,
so
thattheestimatorcanmodifytheobjectbaseusedfortheestimate.
Infact,atwowayexchange(roundtripping)ofBIMgeometrybetweenformats(e.g.BIMouttoIFC
andbacktoBIM)isasofyet,problematic.Aprocessthatcouldexchangeandupdatinggeometryand
integratedatadrivenchangesinvolvessignificantcomplexitybeyondcurrentBIMcapabilities.
ImportanceofVisualDataManagement
OneofthemostimportantfeaturesofBIMisitscapabilitytoexplainbuildingdatathrougha3Dvisual
model.Thisrepresentationgivesitsusersaclearerunderstandingofabuildingprojectandreducesthe
chancesformissingormisrepresentingcomponents.Traditionalcostingapplicationsbytheirnature
havebeen
text
oriented
listing,
tabulating,
and
calculating
lists
of
component
assemblies.
Inthecurrentmarket,InnovayasVisualEstimatingapplicationisanexampleofaBIMbasedcosting
applicationthatemploysarobustinterfaceforvisualmanipulatingthemodelanditscomponentsfor
costingpurposes.TheBuildingExplorerapplicationbuildsonRevitsvisualinterfacetocomposea
graphicinterfaceforinteractivecostinganalysis.
Thecapabilitytovisuallyselectobjectstoquantifyordisplaybuildingcomponentsbyuserdefined
groups(beitCSIformats,phase,orcomposition)withcolorcodingofferstheestimatorsapowertoolto
performmoreinformeddecisionsandinvestigatemultiplewhatifscenarios.Contrarytobeingreplaced
bytechnology,costestimatorswillfindtheirrolesenhanced,freedfromthetediumofquantifyingwith
moretimetoperformhigherlevelduties.
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Figure10InnovayaVisualEstimatingapplicationscreen
Figure11:Structuralcomponentcosting,BuildingExplorerapplication
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Conclusion
BuildingInformationModelingoffersthecapabilitytodevelopprojectcostinformationwithmore
accuracythroughouttheentirebuildinglifecycle.ThekeytosuccessfuluseofBIMbasedcostingwillbe
thedevelopmentofprocessesandmethodswithinorganizations.Thelevelofdetailrequiredina
buildingmodelwillvarydependingonprojectphases,frompreliminary(macro)costingmodelstovery
detailedmodels
required
for
micro
costing
activities
during
the
construction
phase
DataexchangebetweenBIMandcostingapplicationscanbeaccomplishedinseveralwaysAPIs,ODBC
andIFCsamongthem.Themannerchosenwilldependonthesoftwaredevelopersintent.Professionals
usingBIMcostingapplicationswillneedtoselectamethoddependingonprojectphaseandthedetail
required,anddevelopinhousestandardsandproceduresforaligningtheirmodelswiththeestimating
processes.
IndustrystandardsfordataexchangeIFCsinparticularandframeworksforinformationclassification
(e.g.OmniClass,UniFormat)areintegraltoindustryinteroperability.Asmanystandardsarestill
developing,soareBIMapplications.ProfessionalsusingBIMwillhavetoadoptstrategiestointegrate
andchangeasthesetechnologiesmature.
BIMoffers
the
promise
of
acentral
detailed
database
for
arange
of
project
applications,
and
its
visual
capabilitiesforallofthemshouldbeanotableadvantagewhenconsideringhowprofessionalscan
changeandmanagebuildinginformationthroughoutaproject.Asnewtechnology,BIMassistedcost
estimatingwillnotobsoleteestimators;rather,itpromisestofreethemtofocusonhighervaluetask
thancounting,returningincreasedvaluetoprojectprocesses.
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References
SpecifyingandCostEstimatingwithBIM,RobertPaulDean,AIA,CSI,CCS,andSusanMcClendon,RA,CSI,
CCS.Architech,April2007
123Revit:BIMandCostEstimating,RickRundell,CadalystMagazine,AugustandSeptember2006.
NewToolsDeliverBIMData,H.EdwardGoldberg,CadalystMagazine,December2003
PreconstructionManagementSoftwareTrendsandStrategy,RiverguideInc.,October2006.
AACERecommendedPracticeNo.17R97:CostEstimateClassificationSystem,AACE,Inc.,1997.
ADifferentApproachtoUsingIFCstoFacilitateInteroperabilityintheBuildingIndustry,JimForester
andIanHowell,AECbytesViewpoint#15,April13,2005.
CSIFormatsandBuildingInformationModels,RogerJ.Grant,AIAEdges,2006.
http://www.aia.org/nwsltr_tap.cfm?pagename=tap_a_200611_CSI_formats
VisualEstimating:
Extending
BIM
to
Construction.
Lachmi
Khemlani.
AECbytes.
March
21,
2006.
http://www.aecbytes.com/buildingthefuture/2006/VisualEstimating.html
BIMCostingApplications:
InnovayaVisualEstimating http://www.innovaya.com
BuildingExplorer http://www.buildingexplorer.com
U.S.CostSuccessDesignExchange http://www.uscost.com
TrelligenceAffinity http://www.trelligence.com
BeckDprofiler http://www.dpearth.com
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AboutLouiseSabol
LouiseA.
Sabol
is
aregistered
architect
with
more
than
25yearsofexperienceinthebuildingandtechnology
professions.AtDesign+ConstructionStrategies,LLC,
Ms.SabolservesasDirectorofTechnology,providing
overalltechnicalplanningforthefirmstechnology
integrationprojectsfororganizationsinvolvedin
complexcapitalprojects.
AboutDesign+ConstructionStrategies,LLC
DCStrategiesis
dedicated
to
business
technology
implementationandthecreationofITenabledculture
intheAECcommunity.
OurclientsincludetheU.S.DepartmentofState,the
GeneralServicesAdministration,theInternational
CodeCouncil,Autodesk,Inc.andGreenwayConsulting.
Moreinformationisavailableatwww.dcstrategies.net.
Design+ConstructionStrategies,LLC
11DupontCircle,Suite601
Washington,DC20036
(202)2220610
www.dcstrategies.net
Copyright2008Design+ConstructionStrategies.All
rightsreserved.
Design+ConstructionStrategiesandtheDesign+
ConstructionStrategieslogoaretrademarksofDesign+
ConstructionStrategies.Othernamesmaybe
trademarksof
their
respective
owners.