Building from End-of-Life: An Alternative Approach …...1 Building from End-of-Life: An Alternative Approach for Low-Cost Urban Housing Felix Raspall1, Mohit Arora2 1Architecture

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BuildingfromEnd-of-Life:AnAlternativeApproachforLow-CostUrbanHousing

FelixRaspall1,MohitArora21ArchitectureandSustainableDesignPillar,SingaporeUniversityofTechnologyandDesign,

E-mail:[email protected],SingaporeUniversityofTechnologyandDesign,

E-mail:[email protected]

ABSTRACT

Rapidexpansionofcitiesposesaveryhardchallengetoprovideadequatehousingforthepoor,whileitssocialandenvironmentalpressuresdemandalternativeapproachestolow-costhousing.Ananswertothechallengeofhousing forpoorcitizenscancome fromcities themselves.Urbancentersareconcentratednodeswherevast quantities of materials and energy are consumed in constant cycles of construction, operation anddemolition.Strategicallyinterveningintheurbanmetabolismcanhelptosecureverylow-costorevenno-costconstructionmaterialswhilereducingtheenvironmentalstressesduetoresourceextraction,leadingtomoresustainablecities.

Ourresearchinvestigatesthepossibilitiesoftappingintothelifecycleofconstructionmaterialsasasourceofunexploitedbuildingcomponentsforlow-costhousing.Intheinformalcity,amarketofsalvagedmaterialsisalreadyinplace.However,inthedevelopedworld,reusepracticesinconstructionaretypicallydismissed.Herewe present the current building demolition methods in Singapore and a proposal to divert resources thatcurrentlygotolandfill,toproducelow-costhousingfordevelopingnations.Theresearchhastwocomponents.First,studytheflowofmaterials,processesandrelatedstakeholdersinconstructionanddemolitionactivitiesin Singapore, with focus on their economic and environmental dimensions. Second, weworkwith housingdevelopmentagencies,primarilyHabitatforHumanity,inthedesignoflow-costhousingunitsusingreclaimedbuildingcomponentswithminimumcost.

This research contributes with strategies to secure very low-cost housing units using reused buildingcomponents,focusedonthefunctional,aestheticandeconomicaspects.Inthisway,itproposesandsupportsan alternative approach to the urgent urban housing problems through sustainable end-of-life buildingsmanagement,promotingamoreglobal-inclusivemodelofurbanization.

KEYWORDS:Low-CostHousing,UrbanMining,UrbanMetabolism,ConstructionandDemolitionWaste

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AUTHORBIOGRAPHY:

FelixRaspall isanarchitectanddesignresearcher investigatingtherelationshipsbetweendesign,materialityandtechnology.Currently,heisanAssistantProfessoratSingaporeUniversityofTechnologyandDesign.Hisworkexploresalternativedesignmethodsinwhichmaterialconstraintscreativelyinformprojects.

Beingadoctoralcandidate,MohitAroraisworkingintheareaofresourcesefficiency,urbanminingandreuseincomplexurbansystems.Exploringtheinterdisciplinaryengagementofdesign,technologyandenvironmentremainshiskeyinterestforresearch.

IntroductionCities and buildings remain central to research focus on resources and energy efficiency for reducingvulnerabilitytowardsclimatechange[1].Today,flowofmaterialincitiesishighlyinefficient,asthemajorityofconstructionmaterials come from extraction and, by the buildings’ end-of-life, almost all demolition debrisends up in landfill [2, 3, 4]. Rapid expansion of cities and its social and environmental pressures demandalternativeapproachestolow-costhousing.Citiesthemselvescanprovideananswertothepressinghousingchallenges. Strategically intervening in the urban metabolism can help to secure very low-cost or no-costconstructionmaterialswhilereducingtheenvironmentalstressesduetoresourceextraction[4].Ourresearchinvestigatesthepossibilitiesoftappingintothelifecycleofconstructionmaterialsasasourceofunexploitedbuilding components for lowcosthousing. In the informal city, amarketof salvagedmaterials is already inplace.However,inthedevelopedworld,reusepracticesinconstructionaretypicallydismissed.

Throughour analysis of existingdemolitionpractices in Singapore and low cost housing construction in theASEAN region, we identified main opportunities and challenges to accomplish a very low-cost housingproduction model that taps into the end-of-life of buildings in Singapore. In this ongoing research, weinvestigatetheprocessesandsystemsinplaceaswellasdesignmethodstotakeadvantageofexistingurbanstock,andtesttheimplementationofdesignedprocesses.

BuildingDemolitionandLow-costHousingDue to increase in the rate of building obsolescence, current demolition practices in Singapore involvesubstantial disposal of building components that are still in good condition and suitable for reuse for theconstructionofnewunits[4].AlthoughcurrentSingaporeanpoliciespromotelandfillreductionthroughhighdisposalfee,whichmakediscardingofdemolitionwasteexpensivefordevelopersanddemolitioncontractors,there isnoestablishedpracticeormarketforreusedbuildingcomponents inSingapore.Forthisreason,theprocurement of salvaged building components can be extremely cheap or even profitable, creating anopportunitytoutilizethemintheconstructionofverylow-costhousingunitsfortheimmediateASEANregion,where housing needs are urgent. Image 1 displays the current material flow in Singapore and the targetintervention.

Here,wepresentthecurrentbuildingdemolitionmethodsinSingaporeandhowtobetteremployresourcesthatcurrentlygo to landfill for low-costhousingor refugeeshelters.Thisongoingresearch isorganized intothreemodules: (1) studyof currentdemolitionpractices in Singapore, (2) developmentof low-cost housingemployingreusedcomponentsand(3)implementationofthereuseprocess.

CurrentdemolitionpracticesandstateofartinSingapore

First,westudyindetailtheflowofmaterials,processesandrelatedstakeholdersinSingapore,withfocusontheireconomicandenvironmentaldimensions.Theobjective istounderstandexistingpracticesand identifyareas of opportunity to procure used building components that today end up in landfill with a cost to thedemolitioncontractors.Theresearchwasdonethroughinterviewswiththemainstakeholders,sitevisits,andliteraturereview.

ResearchrevealsthatalthoughSingaporehasahighrateofconcreteandmetalrecycling,reusepracticesarenegligible. Themain reason is the lack ofmarket for reused components due to the perceived decrease inconstructionqualitywithinaveryexpensive realestatemarket, thepreference for sleeknewbuildings,andtheconcentrationofconstructionactivitiesinlargepublicandprivatedevelopers.

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The process of demolition largely remains a machine intensive effort with manual sorting of low valuecomponents.Onceabuildingisdesignatedfordemolition,variousdemolitioncontractorsparticipateinabidtopayforbuildingdemolition.Aqualitativeestimationofmetalscrapinbuildingformsthebasisfornegativeorpositivecostofdemolitionforthebuildingowner.Ifthescrap/metalcomponentsarehigh,mostlikelytheowner will get paid for building demolition. Keeping heavy and voluminous nature of construction anddemolitionwaste inmind, theNationalEnvironmentAgencyofSingapore followsapunitivemeasure for itsreductionwithlandfillgatefeeofS$77/Ton.Undersuchcircumstances,theconstructionanddemolitionwasteisdowngradedforapplicationat landreclamationsitesorashardcorealternativeforbottomlayers inroadconstruction. Although the National Environment Agency estimates 99% recycling of Construction anddemolitionwaste,theactualpercentageofcleanconcreterecoveredandrecycledintostructuralconcreteishardtoestimatebutmostlikelyremainssubstantiallylower.Though,Singaporedemolitionguidelines,SS557(2010), provide systematic approach for building demolition to maximize resources recovery, itsimplementationremainslargelyinvisible.Themajorreasonishigherlaborcostinvolvedinresourcerecovery,absenceofreusemarketandstricttimelinetocompletedemolition.Lackofmarketinmanywaysseemsbighurdleinachievingefficientreuseofbuildingcomponents.Currentdemolitionpracticestargetmetalrecoveryassolesourceofvalue.DuetoSingapore’sGreenMarkrequirements(thelocalbuildingratingtool),someofthe portion of concretewaste reaches recycling plants to become recycle concrete aggregates (RCA)whichmostly find lowvalueapplications in temporary construction.Due to lackof recycling facility anda cost forwaste-to-energyplants,glassandwoodencomponentsaremostlycrushedandmixed intoconstructionanddemolitiondebrisorinsteadsenttoaincineration/waste-to-energyplant.Occasionallyinformalcollectorstakeoutgoodconditionedwoodelementsandfurnitureforsaleinnearbycities.Variouspipingandair-conditionductsareusuallytreatedasmetalsandrecoveredafterdemolition.

Tobrieflysummariesthebuildingdemolitionprocess,demolitionmachinesarelandedontopfloorofbuildingaftercreatingapassingway forvehicles (Image2).A topdownapproach is followed tominimize thespacerequirement for logistics. Lift holes serve as a passage for building debris to ground floor where debris iscrushed to remove metal rebar and other metallic components. To extract smaller magnetic metalcomponents, amagnet is used in the presence of workers who remove any non-magneticmetal thatmayremainat thepileofdebris.Aftermetalextraction,debris is senteither to landfillor land reclamationsiteswhile good quality concrete from columns and beams is sent for recycling into RCA. Current practice ofdemolitionremainslargelydevoidofsecondlifeofmaterialsintheformofreuse.

Thus, current demolition practices provide an opportunity to reuse building components for high levelapplications in low-costhousing. Ifdoneata largescale,urbanminingofbuildingcomponents indevelopedcitiescangreatlyimprovetheeffortsforachievingadequateurbanhousingindevelopingcountries.

Toimplementthisprocess,anumberofchallengesneedtobeovercome.Thewindowoftimewhenmaterialscanberecoveredisveryshort,aroundonetotwoweeksatthebeginningofthedemolitionprocess.Today,demolitioncontractorsusuallyinvite“acquaintances”enterthesiteand“scavenge”forfurnitureatminimumcost. Beyond this timeframe, recovery activities, which can entail delays in the demolition process, areconsideredunreasonable.

Low-costhousingusingreusedcomponents

Second,westudyhowtodesignlow-costhousingunitswithproperhabitabilitylevelsandminimumcostusingdiscardedmaterials.We are currently working in collaboration with Habitat for Humanity in the design ofprototypical unit for Batam, Indonesia, a city 15km from Singapore where Habitat for Humanity has beenconductingsignificantconstructionwork.

Ourfirststepistostudyhowrecoveredmaterialscanbeusedinlow-costunitsandhowtofacilitatematerialrecoverywithintheshortwindowoftimethatdemolitionpracticescanoffer.Asacasestudy,westudiedthereusabilityofabuildingsoon tobedemolished, theRochorCentre inSingapore.Weproposedand testedaprocesstoquicklysurveythebuildingusing3dpointcloudscanning,whichaimstosimplifytheidentificationoftheexistingmaterialstock.Thisiscrucialtoexpeditethetightrecoveryprocessandtofacilitatethedesignoflow-costunits.Theactualsurveyofthebuildingtooktwohoursonthesite,andproduceda3dmodelthatwasusedtoidentifyusefulpartsandlocatecomponentstoberecoveredforourlow-costhousingunits(seeImages3and4)

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Materialsthataresuitabletoberecoveredinclude:windows,doors,kitchencabinets,bathroomandkitchenfixtures, and surface finishing in good condition. In addition, concrete components such asbeams, columnsandslabs,ifcarefullytakenapart,canalsobereused.

The second step is the design of housing units that can be tailored to the particular characteristics of therecoveredcomponents.Designingusingrecoveredmaterialspresentschallengestodesignersduetothenon-standardnatureofmaterials [5, 6]. As a benchmark,webasedour design in a prototypical unit for Batam,Indonesia,byHabitatforHumanity(seeImage5).Ourdesignfollowsitsbasiclayout,replacingnewmaterialswith reused components from the Rochor Centre. Image 6 displays a design we propose for the low costhousing.

Implementation

Theimplementationofthereuseprocessinvolvesanumberoforganizationalandlogisticchallenges.Wearecurrently working towards understanding and overcoming those challenges by designing and building aprototypicalunit.

Astoday,wehaveestablishedanewbridgebetweensupplyanddemandforreusedcomponents:demolitioncontractorAiksunEngineeringandDemolitionPteLtdonthesupplysideandwithHabitatforHumanityonthedemandside.Bothpartieshavestated theirwillingness to facilitate theprocess.OurworkatSUTD involvescoordination,designandexecution.

We anticipate a number of logistic needs: A small warehouse space in Singapore, transportation from thedemolition site to theassembly spaceand to the finaldestination, and construction in the final location. Interms of cost, uncertainties are still high. Cost of building components involve labor to disassemble andtransportation from the site to the assembly space. In addition, new constructionmaterials and labor areneeded in the construction site. We aim to have a clear understanding of the actual costs through theprototypicalunit.

ConclusionThis research contributes with strategies to produce very low-cost housing units using reclaimed buildingcomponents,focusedonthefunctional,aestheticandeconomicaspects.Inthisway,itproposesandsupportsan alternative approach to the urgent urban housing problems through sustainable end-of-life buildingsmanagement.

We have already tested the feasibility of this approach in theory, by cooperating with the relevantstakeholders,surveyedarealdemolitionsiteanddesignedapossibleunit.Inaddition,wedesignedaprocesstofacilitatethesurveyofbuildingstocktobedemolished,therecoveryofcomponentsandthedesignofnewunitsusingafast3Dpointcloudscanning.WetestedthisprocessbyscanningtheRochorCentreinSingapore,cataloguingusefulcomponentsanddesigningaunit.

To implement thisproject,we identifieda largenumberofpractical concerns includingcostingand logisticsthat we aim to answer through actual construction of a prototypical unit in the next year, includingtransportation of materials, assembly space in Singapore and procurement of new materials and finalassemblyonsiteinBatam,Indonesia.Successofsuchanattemptmayfacilitatetoopenupanewdirectionforsecondlifeofbuildingcomponentsingeneralandurbancontributionforlowcosthousinginparticular.

AcknowledgementThe authors acknowledge contribution of Denise Nicole Lim Jeay Yee and Bai Xueni, students under theSingaporeUniversityofTechnologyandDesignUndergraduateResearchOpportunityProgram(UROP),inthisproject.AuthorsthankHabitatforHumanitySingapore,AiksunDemolitionandEngineeringPte.Ltd.,NationalEnvironmentAgency,BuildingandConstructionAuthorityandHousingDevelopmentBoardSingaporefortheirsupportandinputsinresearchwork.

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References1. Kammen, Daniel and Sunter, Deborah. City-integrated renewable energy for urban sustainability. Science,

352 (6288): 922-928, 2016. 2. Fertner, Christian and Große, Juliane. Compact and resource efficient cities? Synergies and trade-offs in

European cities, European Spatial Research and Policy, 2016 3. Hoornweg, Daniel, Bhada-Tata, Perinaz and Kennedy, Chris. Waste production must peak this century,

Nature, 502: 615-617, 2013. 4. Arora, Mohit, Raspall, Felix and Silva, Arlindo. Mining the Urban Ore: Opportunities for Intervention in

Resource Constrained Smart Cities, 11th Conference on Sustainable Development of Energy, Water and Environment Systems, Lisbon, Portugal (Accepted), 2016.

5. Design for Reuse Primer, 2nd Edition, Public Architecture, San Francisco, 2010. 6. Raspall, Felix. “Design with Material Uncertainty”. In Proceedings of the Design Modelling Symposium

Conference Copenhagen 2015. Springer, 2015.

GraphicWork,Images

Image1.DiagramofcurrentmaterialflowinSingapore(left)andoftargetflowafterintervention(right).

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Image2.TypicaldemolitionsiteinSingapore.ImageCredits:MohitArora

Image3.3dpointcloudscanningoftheRochorCentreinSingapore.ImageCredits:FelixRaspall

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Image4.3DscanpointcloudofRochorCentreinSingapore.ImageCredits:FelixRaspall

Image5.Prototypicallow-costhousingdesignforBatam,IndonesiabyHabitatforHumanity.ImageCredits:

HabitatforHumanitySingapore

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Image6.Designforverylow-costhousingusingcomponentsfromtheRochorCenterSingapore.