JANCREMERS*

ENVIRONMENTALIMPACTOFMEMBRANEANDFOILMATERIALSANDSTRUCTURES

–STATUS QUOANDFUTUREOUTLOOK

WPŁYWMEMBRANORAZMATERIAŁÓWISTRUKTURFOLIOWYCHNAŚRODOWISKO–STATUS QUO

I PERSPEKTYWYA b s t r a c t

Inearlytimesanduntilthe1970smostofthemembranestructuresbuiltweremeanttobetemporary.ThisappliestoearlyRomanshadingsystems,military,nomadandcircustents,aswellastoFreiOtto’searlyoeuvres.Theglobalbuildingsectorasawhole,isofgreatimportancewithregardtoafuturesustainableuseofourplanet’sresources:Here,approx.50%ofallprimaryresourcesand40%ofallprimaryenergyareused,and30%ofallgreenhousegasesareproduced.Also,thesectorisresponsibleforupto40%ofallsolidwaste1.Thispaper2providesanoverviewonthecomplexaspectsofenvironmentalimpactsofmembranematerialsandstructures,andhowtomeassurethemusinglifecycleassessmentmethodology.Itbrieflyshowswherethiskindofinformationisused(e.g.,forbuildingassessmentsystems/ratingschemes)andfinallyindicatesthecurrentstatusinthemembranesector.

Keywords: Membranes, PTFE/glass, ETFE Foil, PVC/PES, Photovoltaics (PV), Life Cycle Assessment (LCA), Grey Energy, Environmental Product Declaration (EPD), Building Assessment Systems, Building Rating Schemes

S t r e s z c z e n i e

Ażdo1970rokuwiększośćkonstrukcjimembranowychbyłotraktowanychjakotymczasowe.Odnosisiętodowczesnychrzymskichsystemówosłonprzeciwsłonecznych,wojskowych,pasterskichicyrkowychnamiotów,jakrównieżdowcze-snychkonstrukcjiFreiaOtto.Globalnysektorbudowlanyjawisięjakoniezwykleistotnywkwestiiprzyszłegozrównowa-żonegowykorzystania zasobównaszej planety. Jest odpowiedzialny zawykorzystanie około50%pierwotnych zasobównaturalnych,40%pierwotnejenergiiizaprodukcję30%gazówcieplarnianych.Znimjestzwiązanarównieżprodukcja30%stałychodpadów.Artykułstanowikompleksowyprzeglądaspektówwpływówśrodowiskowychmateriałówikonstrukcjimembranowych,jakrównieżporuszazagadnieniesposobuichcharakterystykimetodąocenyichcyklużyciowego.Wskazujerównież,gdzietakainformacjajestwykorzystywana(np.wsystemachocenybudowlanej,metodachklasyfikacji)iostatecz-nieoceniaobecnystatussektoramembran.

Słowa kluczowe: membrany, PTFE/szkło, folie ETFE, PVC/PES, ogniwa fotowoltaiczne, ocena cyklu życiowego (LCA), szara energia, deklaracja produktu środowiskowego (EPD), systemy oceny budynków, systemy klasyfikacji budynków

* Prof.Ph.D.Eng.JanCremers,UniversityofAppliedSciences,Stuttgart.1 AccordingtoM.Atif,ChairmanIEABuildings&Communities,CISBAT2007.2 Thispaperbuildsonmaterialpartlypublishedbeforein[1–4],itreflectsthestatusonthesubjectofmid2013.

TECHNICAL TRANSACTIONSARCHITECTURE

7-A/2014

CZASOPISMO TECHNICZNEARCHITEKTURA

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1. Introduction, key environmental issues affecting architectural fabric structures and the global picture

Increasingenergyefficiencyintheoperationofbuildingsisamajorchallengeofourtime.Thisnormallyreferstotheenergydemand(non-renewable)torunthebuilding.Butwealsohavetofocusontheenergyconsumption(“greyenergy”)andenvironmentalimpactofthematerialsandstructuresusedforourbuildings,withregardtotheirfulllifecycle,fromtheproductiontorecyclingordisposal.Thismeans,toaddthetopicsoflimitedresources,wasteandenvironmentalimpactsofmaterialsandprocessestothebalancesheetandtherefore,totheagenda.It is important tounderstandthat theeffectsofourplanningdecisionsextenddeeply into thefuture.Andwith increasingenergyefficiency, therelative impactof‘greyenergy’ofbuildingmaterialsandprocessesbecomesmuchmoreimportant(cp.Ill.2).

Mostbuildingsusingfoilandcoatedtextilematerialstodayaremeanttolastfordecades.Themembraneindustryisproudtoalsoofferthisperspectivetoitsclientswhentheyembarkonitsmaterialsandstructures.Inparallel,theplanet’sresourcesareshrinkingandbecomemoreandmorecontestedandhard-fought.Comparedtootherindustrybranches,thebuildingsectorisstilllackingefficiencyintheuseofmaterialsandrationalizationbecausetheoverallrecyclingrateisverylow.

Withregardtothemembraneindustryweseeatwo-faceddiscussion:Ontheonehand,weapplypolymersthatuseoftheenormousamountsofenergyfortheirpro-duction.Theycontainahighamountofprimaryenergyinrelationtotheirmassandemissionsfromsomeofthematerials,canpresentdangersfortheenvironmentandusers.Thisisaglobalissue:Membranematerialsaperceivedasbeingpartoftheworldofpolymers(“plastics”).Andplasticdebrisiseverywhere–onlandandatsea,andondifferentscales:frombigandvisiblethingslikePETbottlesandplasticbagstoextremelysmall,sand-sizedthingswhichgetintothefoodchainandbecomeathreattomanyanimals(fish,birdsandothers).Andincontrasttoacommonexpectation,polymersintheenvironmentareaverylonglastingtypeofmaterial.

Ontheotherhand,theyhaveanundoubtedpotentialforgeneratingresourceandenergysavingsthroughtypesofconstructionthatutilisethesematerialsveryefficiently.

2. Traditional reasoning why membrane strcutures are beneficial to the environment

Whenitisarguedthatmembranestructuresandmaterialsareenvironmentiallyfriendly,people commonly refer to the very low mass per area of membrane material. There isasignificantweightreductioncomparedtoalternativetransparentortranslucentmaterials:

ETFEfoil ~0,5kg/m2

coatedfabric <1,8kg/m2

PC/PMMA(6–8mm) ~5kg/m2

glass(10mm,laminated) ~25kg/m2

membrane/foilvs.PC ~1:3upto1:10membrane/foilvs.glass ~1:10upto1:50

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But therearemorereasonswhy theuseofmembranematerialpotentially reduces theweightofabuildingstructurepersquaremeter:Theuseofmembranesasacovermaterialallowforhighdeflectionwithintheprimarystruc-ture.Thisapplies to thebuidlingenvelope, i.e. facades,butmostofall toroofstructures.Membranematerialsthemselvesarefarlighterthanrigidalternativematerials.Thisleadstoareductionofdownloads,alsoincombinationwithsnowloadsandthustoalighterprimarystructure.Comparedtoothertranslucentmaterials,secondarystructurescanbesignificantlyreduced (due to larger spanpotential and/or reduced safety issues).Typically, increaseofsecondarysteelofanon-membranesolution3:100–200%.

Combiningmembranematerialswithcablestructures,offerahighpotentialforfurtheroptimizing: Soft membrane materials allow for larger deflections compared to glass orpolycarbonate(PC).Theyallowforlargespanwidthsofmaintrusses.Noexpansion/movementjointsareneededwithinmembranecoveringcomparedtorigidsolutions.Membranecablestructurescanbedesignedtobevirtuallymaintenancefreedependingontheproperchoiceofmaterials(e.g.,aluminiumextrusions,stainlesssteelfittings),installationprocedures,etc.Thismightbeakeybenefit,aslatermaintenanceworkonconventionalstructurestendtobeagreatdealandeffort(forexample,attheinterfaceoftrussesandcoveringmaterials).Thesebenefitsofcombinedcableandmembranestructuresarecommonlyusedandhaveleadtoagreatvarietyofprojectsusingthistechnology(cp.Ill.1).

Here,someselectedstadiumexamplesarelisted.Whenlookingattheresultingfiguresfor roofarea relatedweight,differentboundaryconditionshave tobe taken intoaccount:Differences in size of the roof, in applying snow loads (Maracana: none,Warsaw: veryhigh),additionalloads(videoscreencubeatWarsaw)orfixed/retractableroofstructure.Asaresult,theweightfiguresprovidedcannotbecomparedonetoone.Thesampleprojectsalsoshowveryclearlythatthe‘engineeringintelligence’ofastructure,additionallyholdsahighpotentialtosaveweight(andthereforedrasticallyreducesitsenvironmentalimpact).

Otheraspectsofmembranestructuresalsohaveaninfluenceonthelifecycleassessmentofamembranestructure.Theseare,forexample,theexpectedlife-time,demandoncleaningandmaintenance:• Servicelife-timeofdifferentpotentialcovermaterials:

– Polycarbonate(inchallengingclimatelikeMiddle-East,Brasil)<15years, – PTFE/glass,ETFEfoil~30years, – Glasslastslonger,butrequirescomplexandcostlysub-structure, – Metalsheetroofsarecheap,butnottranslucentandthereforerequireartificiallighting,alsomaintenanceforwaterproofing,

• Cleaning/Maintenance; – PTFE/glassandETFEfoilare‘self-cleaning’(ifthereisrain), – othermaterialswhichrequirecleaning(water,energy,cleaningagents),mightleadtofasteraging(PC,forexample),

– GlassandPCroofsmightneedsignificantlymoremaintenanceafter10–15yrs,com-paredtoPTFE/glassandETFE(mainlyduetoagingofthewatertightjoints,ascom-paredtoahomogeneousmembranesurface).

3 Samplecalculationbasedon:Maintrussesatadistanceof15m,membranearches~10kg/m2, PC incl.sec.struct.~30kg/m2.

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Ill.1.Comparisonofselectedstadiaprojects:Weightofroofstructureperarea.DataSource:HightexGmbHandKnutGöppert,sbp–SchlaichBergermannundPartner(5–2013)

OlympicStadium,Berlin(2004) •27000m²PTFE-coatedglassfabric,28000m²Meshfabric,6000m²glass

•cantileveredstructure,twomembranelayers•weightofsupportstructureexcludingcladding(33000m²roof)

~106kg/m2

GottliebDaimlerStadium,Stuttgart(1993) •34000m²PVC-coatedpolyesterfabric•spoked-wheelstructure,secondaryarchstructure

•weightofsupportstructureexcludingcladding(incl.compressionring)

~91kg/m2

StadiumMárioFilho(Maracanã),RiodeJaneiro(2013)

•43800m²PTFE-coatedglassfabric/roofarea45500m²

•steelandcablestructure2900t+840t=3740t•weightofsupportstructureexcludingcladding(incl.compressionring)

~82kg/m2

NationalStadium,Warsaw(2011) •55000m²PTFE-coatedglassfabric,10000m²PVC-coatedpolyesterfabric

•spoked-wheelstructure,secondaryarchstructure,largeretractableroof

•weightofsupportstructureexcludingcladding,includingpillarsandfacadesubstructure

~200kg/m2

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Inthediscussionoflifecycleassessment,energyefficiencyetc.,theaspectofamaterialortechnology’sperformance,mustnotbeforgotten.Thisrepresentstheonesideofthecoinwhichcouldbecalled‘value’(vs.‘price’ontheotherside).Theperformanceispartofthe‘use’stage(cp.Ill.3).Here,membranematerialsprovidealotofpotentialwhichcannotbedescribedhere(e.g.,lighttransmissioninabroadrange,highstrength,durability,etc.,cp.[5]).Thisincludesinnovativefunctionalcoatingsonmembranes(e.g., transparentlow-E-coatings),evenactivesolartechnologywhichcanbeintegratedincoatedtextilesandETFEfoils(cp.Ill.4).

Ill.2.TheRelevanceofconstructionmaterialsgrows (source:J.Cremers/PEInternational2012)

Ill.3.AspectsandImportanceoftheUseStageforMembraneMaterialsandStructures (source:J.Cremers)

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Ill.4.FlexiblePVintegratedonETFE(left) andPTFE/glass(right)

(source:J.Cremers/HightexGmbH)

Ill.5.ShoppingMallDolceVitaTejo,desginedbyPromotorioArchitects.Realizedandlow-E-ETFE-developmentbyHightexGmbH.Photograph:HightexGmbH,Bernau

2. Life Cycle Assessment (LCA)

In2011,anewTensinetworkinggrouphasbeenfoundedbyaninitiativeoftheauthor,whichfocuseson thesubjectofLifeCycleAssessment(LCA)in themembrane industry.The aimof this group is to review the current status onmembranematerials and typicalmembrane structureswith regard to LCA issues,which can be used as a key evaluationcriterion,intheobjectificationofthediscussiononmembranematerialsthattheindustryisbasedon.TheLCAapproachaimsforatransparentevaluationofthecomplexenvironmentalimpactsofproductsandprocessesinvolved.Itlooksatthestagesofmaterialorstructure’slife,suchasobtainingtherawmaterials,production,processingandtransport,andalsouse,reuse and disposal if applicable. LCAmeasures environmental impact across a range ofissuessuchasimpact:onairquality,onwaterusageandwaterquality,ontoxicitytohumanlife and to ecosystem functioning, on impact on globalwarming aswell as resource use (cp. Ill. 6). There are not only “cradle-to-grave” assessments that investigate the entirelifecycleofaproduct,butalso“cradle-to-gate”assessmentsthatconsideronlythelifeofaproductuptothetimeitleavesthefactory.DINENISO14040describestheLCAmethodwhichcanbesplitintofourphases:definitionofgoalandscope,inventoryanalysis,impactassessment and interpretation.Finally, all results like reports anddeclarations have to bescrutinisedbyanindependentgroupofexperts,whichisessential,ifcomparativestatements,e.g.,withrespecttorivalproducts,aretobemadeortheresultstobepublicized.

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3. Environmental Product Declarations (EPD)

Drafting a product LCA is a time-consuming and expensive process that is generallycarriedoutfortheproductmanufactureroragroupofmanufacturersbyaspecialistcompany.Theecologicalcharacteristicsofaproductarecommunicated in the formofenvironmentaldeclarations.According to the ISO14020 family, these environmental product declarations(EPD)areclassifiedassocalled“typeIII”environmentallabels,whicharehighlyregulated.Here,themostimportantenvironmentalimpactsofproductsaredescribedsystematicallyandindetail.Thestartingpoint isaproductLCA,but further indicatorsspecific to theproduct(e.g.,contaminationoftheinteriorair)arealsoincluded.Inthisformofdeclaration,itisnottheindividualresultsofmeasurementsthatarecheckedbyindependentinstitutes,butratherconformitywiththeproductcategoryrules(PCR)drawnuptoensureanequivalentdescriptionwithin thatproductcategory.AnEPDdescribesaproduct throughout itsentire lifecycle–allrelevantenvironmentalinformation(cp.Ill.7.Theyarethirdpartyverifiedandguaranteereliabilityoftheinformationprovided.CalculationRulesforEPDsaredefinedbyEPDprogramholders–forbuildingproducts,EN15804isintroducedasarespectivestandardinEurope.

Lifecycleimpactassessmentindicators

Globalwarmingpotential(GWP)Depletionpotentialofthestratosphericozonelayer(ODP)Acidificationpotentialoflandandwater(AP)Eutrophicationpotential(EP)Summersmogpotential(POCP)Abioticdepletionofnonfossilresources(ADPelements)Abioticdepletionoffossilresources(ADPfossilfuels)

Energyindicators Nonrenewableprimaryenergy,excludingfeedstockInputofnonrenewablefeedstockTotalinputofnonrenewableprimaryenergyRenewableprimaryenergy,excludingfeedstockInputofrenewablefeedstockTotalinputofrenewableprimaryenergy

Waterindicator Inputofnetfreshwater

Useofrecycledmaterials InputofsecondarymaterialInputofrenewablesecondaryfuelsInputofnonrenewablesecondaryfuels

Wasteindicators HazardouswastedisposedNonhazardouswastedisposedRadioactivewastedisposed

Exportedmaterials Componentsforre-useMaterialsforrecyclingMaterialsforenergyrecoveryExportedenergy

Ill.6.LifeCycleImpactAssessment/EnvironmentalIndicatorsaccordingtoEN15804 (source:J.Cremers,EN15804)

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EPDshelpinearlyplanningstage,theyshowenvironmentalperformanceofaproductoraproductgroup,theyareoftenusedinpoliticaldiscussionandcanbeabasisforacompany’sinternalbenchmarkandimprovement.

Ill.6.EPDFramework–EN15804(Systemboundaryandmodularityofproductlifecycle).TypesofEPDwithrespecttolifecyclestagescoveredandlifecyclestagesandmodulesforthebuilding

assessment(source:JanCremers/PEInternational)

Ill.7.SampleResultofDGNBassessmentandinteractionofcriteriawithEPDs (source:DGNB/PEInternational)

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4. Impact of LCA to the Membrane Sector

Thereareanumberofdriverstopre-activelyaddresstheLCAissuenow,forexample:• Building assessment systems with country-specific priorities for indicating the build-

ing’s,likeforexample,LEED(LeadershipinEnergyandEnvironmentalDesign),BREE-AM(BuildingResearchEstablishmentEnvironmentalAssessmentMethod)andDGNB(DeutscheGesellschaft fürNachhaltigesBauen/GermanSustainableBuildingCouncil).Thelatter,wasoneofthefirstmethodstoprescribeacertificationsystemthatlooksattheentirelifecycleofabuildingandalsoincludesatypeofbuildingLCAbasedonEPDsoftheindividualconstructionproducts(cp.Ill.8).Thisputsthefocusofplanners,usersandinvestorstotheenvironmentalimpactofawholebuilding(includingtheLCAsofcon-structionproducts).“GreenBuilding”isahighlygrowingmarketshare.

• Competitive situation by comparingmembranematerials and structures to alternativeswithLCAdataavailable.

• Defenceagainstprejudicesbasedonmissing,insufficient,misleadingorwrongLCAdata.• Customersawareness.Communication,onenvironmentalproductperformance,gainsim-

portanceformanufacturersandwillstrengthencustomerrelationship.• LCAdatawillbecomemoreandmoreimportantintenderingandawardprocedures.This

alsoappliestotheuseforConstructionProductRegulation(CPR).• Existingandfuturelegalregulationsonwasteconcerningthebuildingindustry.

Although,theimportanceofthevarioussustainabilitycriteriamayvary,issuesconsideredtobeimportantinclude:• Energyandcarbondioxideemissions(frombuildingoperation).• Materialsandresourceuse(includingembodiedenergy).• Wasteminimisation,includingrecycling.• Transport(inrelationtotheuseofthebuilding).• Waterconservationanduse(withinthebuilding).• Landuseandecology.• Minimisingpollution.• Constructionandbuildingmanagement(includingsecurity).• Healthandwell-beingwithinthebuilding.

Materialandbuildingcomponentselectionhasadirectimpactonthebuildingdesignandperformance,andhenceaffectstheoperationalenergyuseandthehealthandwell-beingofitsoccupants.Therefore,themembraneindustryneedstoquantifythesebenefitsinordertomaximiseitssustainabilitycredentials.

5. Additional Political Background Information

WiththeadventoftheEuropeansinglemarketforconstructionproducts,theEuropeanCommissionbecameconcerned thatnationalEPDschemesandbuilding levelassessmentschemes would represent a barrier to trade across Europe. The EU therefore, soughtamandatefromtheEUMemberStatestodevelopEuropeanstandardsfortheassessmentofthesustainabilityperformanceofconstructionworksandofconstructionproducts.ThismandateiscalledCEN/TC350.From2010,Europeanstandardsbegantoemergefromthis

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processandStandardBSEN15804waspublishedinFebruary2012providingcorerulesforconstructionproductEPD.

TheConstructionProductsDirectiveof1989,wasoneofthefirstDirectivesfromtheEUCommissiontocreateacommonframeworkfortheregulationsonbuildingsandconstructionproducts.IthasbeenreplacedbytheConstructionProductsRegulation(CPR)andislegallybindingthroughouttheEU.TheCPRincludesrequirementsforthesustainableuseofnaturalresources,thereductionofgreenhousegasemissionsoverthelifecycleandtheuseofEPDforassessingand reporting the impactsofconstructionproducts. If anEUMemberStatewishestoregulateintheseareasofsustainability,itmustuseEuropeanstandardswheretheyexistwhenregulatingandmustwithdrawnationalstandards.Thismeans,thatinthecaseoftheCPR,aMemberStatemustusetheCEN/TC350suiteofstandards.

AnEPDprovidesrobustandconsistent informationthatcanbeusedinbuildinglevelassessmentsandtheguideelaboratesonthevarietyofwaysthatthiscanbedone.Inaddition,anumberofbuildingleveltoolsareemergingaimedatimprovingdecisionsat thedesignstage by combining embodied environmental impact data and whole life cost data (i.e.,economic)andlinkthemtoBIM(BuildingInformationModelling)data.

AcrossEurope,thevariousenvironmentalratingschemesareseekingtoharmonisethewaysinwhichtheyassessproductsandbuildings.Increasingly,modelsareemergingtolinkembodiedimpactswithoperationaldatathusenablingabetterunderstandingofthetrade-offbetweenoperationalandembodiedimpacts,andintime,benchmarksfordifferenttypesofbuildingswillemerge.Allofwhichcontributesgreatlytothegoalofalowcarbon,moreresourceefficient,sustainablebuiltenvironment[7].

6. Current status on LCA on membrane materials and structures

With regard to the status on scientific research on LCA onmembranematerials andstructures,itcanbestatedthatsomerecentpublicationsaddresstheissue[1,4,5,12–19],butthenumberofpublicationsisstillverylow.Also,andmaybemostimportantly,itbecomesobviousfromastudyonexistingliteraturethatthereseemstobeahighuncertaintyintheusability of the LCA data worked with. For example, the values for‚ total input of nonrenewableprimaryenergy’forETFEfoilthatcanbefound,differsignificantly:From26.5MJ/kg[16:325]to210MJ/kg[15].ThevaluesprovidedintheonlyEPDonETFEpublishedsofar4isevenhigher(>300MJ/kg).WhereasthedatasituationonPCV/PESiscomparablysatisfying,therestillishardlyanydataavailableonPTFE/glass.

With regard to fullLCAandEPDs, there are some forerunners, for example, there isafirstcompanyspecificEPDonETFEbythecompaniesVECTORFOILTEC,NOWOFOLand DYNEON (mentioned before). For PVC/PES, LCA-information has been alreadyprovidedin2009provided5bySERGEFERRARIandwascompiledbyEVEAaccordingtoISO14040.ThiscompanyisalsostronglypromotingarecyclingprocessforPVC/PEScalled

4 EPD-VND-2011111-E, 10-2011, Source: Institut Bauen und Umwelt e.V., Webpage: http://ibu-umwelt.de[5-2013].

5 Life cycle assessment of PRECONTRAINT®1002S according to ISO14040 (byEVEA, 2009)(source:SergeFerrari).

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“TEXILOOP”,whichisalreadyinoperationforyearsalreadyandwhichhelpstoimproveLCA-values.A specificwebsite for the recycling process [10] shows the potential of thesubjectformarketingincludingacomparison-tooltoshowthebenefitagainstanincinerationscenario(conventionalend-of-life).

Thecurrentstatus(mid2013)onthesubjectofrecyclingofthemostimportantmembranematerials isas follows:ForPVC/PESthere isa recyclingprocessavailablewhich isalsoinuse(e.g., theTEXYLOOPprocesswhich isalsoopentoFerrari’scompetitors).ETFE,as a copolymer, can be recycled in principle. Currently, we see only downcycling fromETFEfoilcut-offsandwastetoETFEtubessuchasdirt,dust,etc.,wouldlimittheopticalandmechanical properties of the ETFE foil. For PTFE/glass there is a lab-scale process(developedbyDyneon/3MandBayreuthUniversity),whichiscommerciallynotactivesofar,butshowsthefuturepotential.Currently,PTFE/glass,beinganinertmaterial,iscurrentlylandfilled.

Onthelevelofstructuretypes,thereisverylittlepublishedinformationavailablesofar.Somesingleproject-basedcalculationshavebeencarriedout,butduetothelackofproperLCAdata,theyaredifficulttoassessandcompare.Oneexampleforthisappoachhasbeenconductedwithin a largeR&D-project, inwhich the author has been involved in6.Here,acomparingcalculationonprimaryenergy intensityhasbeencarriedout foraglass-roofvs.anETFE-cushion-roof includingspecificlyoptimisedsteelsub-structures(roofareaofapprox.27×33.5m):

Massincl.substructure PrimaryEnergy“invest” (excl.operationandreplacment)

Glass-roof 180t 1270000kWh

Steelandsubstructure 114t 880000kWh

Glazinglayer 66t 390000kWh

ETFE-roof 80 t 693 000 kWh

Steelandsubstructure 78t 640000kWh

ETFE-cushions 1.3t 53000kWh

Inbothscenarios,thereisaneedformaintenance,repairandtypicalreplacementduringtheperiodofoperation.Additionally,theETFE-roofvarianthasaquasiconstantenergydemandforthecushionairsupplysystem(keeping-upinternalpressureanddehumidification).Thisdemandhighly depends on project-specific issues, i.e., fabrication quality (seam tightness), cushiongeometry, typeofclamping,air supplysystem(w/oaircirculation). In thestudy, theenergydemandthereforehasbeenconsideredinthreedifferentvariants(3.65/7.3/11kWh/m2a).Thesignificanceofthisassumptiononan80-year-LCAcalculationisdepictedinIll.9.

6 Cp.projectwebsiteathttp://www.mesg.info[6-2013].

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Ill.8.LCA-resultsofETFEandglassroofvariantsofMESGproject7

R e f e r e n c e s

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[4] Knippers J.,CremersJ.,GablerM.,LienhardJ.,Construction Manual for Polymers + Membranes, Institut für internationaleArchitektur-Dokumentation,Munich/ NewYork:DETAIL/BIRKHÄUSER,2011,cp.Chapter7,124-131.

[5] MollaertM.,Environmental aspects in textile architecture,TeniNet/VrijeUniversiteitBrussel,TRA2003.

7 Source:originalgraphbyKlausPuchta(LHR)publishedin[8,German],thisupdatedversionin[9,English].

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[6] CremersJ.,Soft skins – innovative foil and textile architecture’, Proceedings,vol. I, 21–29, IX-th International Scientific Conference “New building technologies anddesignproblems”,TechnicalUniversityofCracow,Poland,2011.

[7] Anderson J., Thornback J., A guide to understanding the embodied impacts of construction products,ConstructionProductsAssociation,2012.

[8] ManaraJ.etal.,Schlussbericht des BMWi-geförderten Projekts “Membrankon-struk-tionen zur energetischen Sanierung von Gebäuden”(“MESG”).F12B2437,TIBHan-nover,2012,10-15.

[9] LangW.,RamppT.,PuchtaK.,CremersJ.,Examination of Membrane Structures in Building Exteriors Using Typological and Constructive Considerations, StructuralMembranes2013,VI InternationalConferenceonTextileCompositesand InflatableStructures,Proceedings,Munich,2013.

[10] Website for the Texyloop process by Serge Ferrari SA, http://www.texyloop.com(capturedin4.12.2012).

[11] CremersJ.,Kapitel ‘Textiles for insulation systems, control of solar gains and thermal losses and solar systems’ im Buch ‘Textiles, polymers and composites for buildings’ (Ed.byGPohl),WoodheadPublishing/UK,351-374.

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[14] FournierF.,LCAofprecontraint,compositemembranes&Texylooprecyclingcasesstudies.TensinetSymposium2013[Re]thinking lightweightstructures,Proceedings,MimarSinanFine-ArtUniversity,Istanbul,May2013,487-496

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[16] Robinson-GaylesS. et al.,ETFE foil cushions in roofs and atria,Construction andBuildingMaterials,Elsevier,15,2001,323-327

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