2 sabol cost estimating

8/3/2019 2 Sabol Cost Estimating

1/16

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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Design+ConstructionStrategies ChallengesinCostEstimatingwithBuildingInformationModeling

Page2

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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Page3

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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Page4

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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Page5

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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Page6

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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Page7

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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Page8

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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Page9

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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Page10

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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Page12

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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Page13

Figure10InnovayaVisualEstimatingapplicationscreen

Figure11:Structuralcomponentcosting,BuildingExplorerapplication


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Page14

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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Page15

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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Page16

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.

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