Arora, Mohit

Raspall, Felix

English

Rapid expansion of cities poses a very hard challenge to provide adequate housing for the poor, while its social and environmental pressures demand alternative approaches to low-cost housing. An answer to the challenge of housing for poor citizens can come from cities themselves. Urban centers are concentrated nodes where vast quantities of materials and energy are consumed in constant cycles of construction, operation and demolition. Strategically intervening in the urban metabolism can help to secure very low-cost or even no-cost construction materials while reducing the environmental stresses due to resource extraction, leading to more sustainable cities. Our research investigates the possibilities of tapping into the life cycle of construction materials as a source of unexploited building components for low-cost housing. In the informal city, a market of salvaged materials is already in place. However, in the developed world, reuse practices in construction are typically dismissed. Here we present the current building demolition methods in Singapore and a proposal to divert resources that currently go to landfill, to produce low-cost housing for developing nations. The research has two components. First, study the flow of materials, processes and related stakeholders in construction and demolition activities in Singapore, with focus on their economic and environmental dimensions. Second, we work with housing development agencies, primarily Habitat for Humanity, in the design of low-cost housing units using reclaimed building components with minimum cost. This research contributes with strategies to secure very low-cost housing units using reused building components, focused on the functional, aesthetic and economic aspects. In this way, it proposes and supports an alternative approach to the urgent urban housing problems through sustainable end-of-life buildings management, promoting a more global-inclusive model of urbanization

Edinburgh Research Explorer

     Edinburgh Research Explorer                                      Building from End-of-Life: An Alternative Approach for Low-CostUrban HousingCitation for published version:Raspall, F & Arora, M 2016, 'Building from End-of-Life: An Alternative Approach for Low-Cost UrbanHousing', Paper presented at No Cost Housing Conference, Zurich, Switzerland, 30/06/16 - 1/07/16.<https://ethz.ch/content/dam/ethz/special-interest/conference-websites-dam/no-cost-housing-dam/documents/Arora_Building_From_End-of-life_FelixRaspall_MohitArora.pdf>Link:Link to publication record in Edinburgh Research ExplorerDocument Version:Publisher's PDF, also known as Version of recordGeneral rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s)and / or other copyright owners and it is a condition of accessing these publications that users recognise andabide by the legal requirements associated with these rights.Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorercontent complies with UK legislation. If you believe that the public display of this file breaches copyright pleasecontact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately andinvestigate your claim.Download date: 01. Feb. 2023	1		Building	from	End-of-Life:	An	Alternative	Approach	for	Low-Cost	Urban	Housing	Felix	Raspall1,	Mohit	Arora2	1Architecture	and	Sustainable	Design	Pillar,	Singapore	University	of	Technology	and	Design,		E-mail:	felix_raspall@sutd.edu.sg	2Engineering	Product	Development	Pillar,	Singapore	University	of	Technology	and	Design,		E-mail:	arora_mohit@mymail.sutd.edu.sg			ABSTRACT	Rapid	expansion	of	cities	poses	a	very	hard	challenge	to	provide	adequate	housing	for	the	poor,	while	its	social	and	environmental	pressures	demand	alternative	approaches	to	low-cost	housing.	An	answer	to	the	challenge	of	housing	 for	poor	citizens	can	come	 from	cities	 themselves.	Urban	centers	are	concentrated	nodes	where	vast	 quantities	 of	 materials	 and	 energy	 are	 consumed	 in	 constant	 cycles	 of	 construction,	 operation	 and	demolition.	Strategically	intervening	in	the	urban	metabolism	can	help	to	secure	very	low-cost	or	even	no-cost	construction	materials	while	reducing	the	environmental	stresses	due	to	resource	extraction,	leading	to	more	sustainable	cities.		Our	research	investigates	the	possibilities	of	tapping	into	the	life	cycle	of	construction	materials	as	a	source	of	unexploited	building	components	for	low-cost	housing.	In	the	informal	city,	a	market	of	salvaged	materials	is	already	in	place.	However,	in	the	developed	world,	reuse	practices	in	construction	are	typically	dismissed.	Here	we	 present	 the	 current	 building	 demolition	 methods	 in	 Singapore	 and	 a	 proposal	 to	 divert	 resources	 that	currently	go	to	landfill,	to	produce	low-cost	housing	for	developing	nations.	The	research	has	two	components.	First,	study	the	flow	of	materials,	processes	and	related	stakeholders	in	construction	and	demolition	activities	in	 Singapore,	 with	 focus	 on	 their	 economic	 and	 environmental	 dimensions.	 Second,	 we	work	with	 housing	development	agencies,	primarily	Habitat	for	Humanity,	in	the	design	of	low-cost	housing	units	using	reclaimed	building	components	with	minimum	cost.		This	 research	 contributes	 with	 strategies	 to	 secure	 very	 low-cost	 housing	 units	 using	 reused	 building	components,	focused	on	the	functional,	aesthetic	and	economic	aspects.	In	this	way,	it	proposes	and	supports	an	 alternative	 approach	 to	 the	 urgent	 urban	 housing	 problems	 through	 sustainable	 end-of-life	 buildings	management,	promoting	a	more	global-inclusive	model	of	urbanization.	KEYWORDS:	Low-Cost	Housing,	Urban	Mining,	Urban	Metabolism,	Construction	and	Demolition	Waste			2		AUTHOR	BIOGRAPHY:		Felix	Raspall	 is	an	architect	and	design	researcher	 investigating	the	relationships	between	design,	materiality	and	technology.	Currently,	he	is	an	Assistant	Professor	at	Singapore	University	of	Technology	and	Design.	His	work	explores	alternative	design	methods	in	which	material	constraints	creatively	inform	projects.	Being	a	doctoral	candidate,	Mohit	Arora	is	working	in	the	area	of	resources	efficiency,	urban	mining	and	reuse	in	complex	urban	systems.	Exploring	the	interdisciplinary	engagement	of	design,	technology	and	environment	remains	his	key	interest	for	research.	Introduction	Cities	 and	 buildings	 remain	 central	 to	 research	 focus	 on	 resources	 and	 energy	 efficiency	 for	 reducing	vulnerability	towards	climate	change	[1].	Today,	flow	of	material	in	cities	is	highly	inefficient,	as	the	majority	of	construction	materials	 come	 from	 extraction	 and,	 by	 the	 buildings’	 end-of-life,	 almost	 all	 demolition	 debris	ends	 up	 in	 landfill	 [2,	 3,	 4].	 Rapid	 expansion	 of	 cities	 and	 its	 social	 and	 environmental	 pressures	 demand	alternative	approaches	to	low-cost	housing.	Cities	themselves	can	provide	an	answer	to	the	pressing	housing	challenges.	 Strategically	 intervening	 in	 the	 urban	 metabolism	 can	 help	 to	 secure	 very	 low-cost	 or	 no-cost	construction	materials	while	reducing	the	environmental	stresses	due	to	resource	extraction	[4].	Our	research	investigates	the	possibilities	of	tapping	into	the	life	cycle	of	construction	materials	as	a	source	of	unexploited	building	 components	 for	 low	cost	housing.	 In	 the	 informal	 city,	 a	market	of	 salvaged	materials	 is	 already	 in	place.	However,	in	the	developed	world,	reuse	practices	in	construction	are	typically	dismissed.		Through	our	 analysis	 of	 existing	demolition	practices	 in	 Singapore	 and	 low	 cost	 housing	 construction	 in	 the	ASEAN	 region,	 we	 identified	 main	 opportunities	 and	 challenges	 to	 accomplish	 a	 very	 low-cost	 housing	production	 model	 that	 taps	 into	 the	 end-of-life	 of	 buildings	 in	 Singapore.	 In	 this	 ongoing	 research,	 we	investigate	the	processes	and	systems	in	place	as	well	as	design	methods	to	take	advantage	of	existing	urban	stock,	and	test	the	implementation	of	designed	processes.			Building	Demolition	and	Low-cost	Housing	Due	 to	 increase	 in	 the	 rate	 of	 building	 obsolescence,	 current	 demolition	 practices	 in	 Singapore	 involve	substantial	 disposal	 of	 building	 components	 that	 are	 still	 in	 good	 condition	 and	 suitable	 for	 reuse	 for	 the	construction	of	new	units	[4].	Although	current	Singaporean	policies	promote	landfill	reduction	through	high	disposal	fee,	which	make	discarding	of	demolition	waste	expensive	for	developers	and	demolition	contractors,	there	 is	no	established	practice	or	market	for	reused	building	components	 in	Singapore.	For	this	reason,	the	procurement	 of	 salvaged	 building	 components	 can	 be	 extremely	 cheap	 or	 even	 profitable,	 creating	 an	opportunity	to	utilize	them	in	the	construction	of	very	low-cost	housing	units	for	the	immediate	ASEAN	region,	where	 housing	 needs	 are	 urgent.	 Image	 1	 displays	 the	 current	 material	 flow	 in	 Singapore	 and	 the	 target	intervention.	Here,	we	present	the	current	building	demolition	methods	in	Singapore	and	how	to	better	employ	resources	that	currently	go	 to	 landfill	 for	 low-cost	housing	or	 refugee	shelters.	This	ongoing	research	 is	organized	 into	three	modules:	 (1)	 study	of	 current	demolition	practices	 in	 Singapore,	 (2)	 development	of	 low-cost	 housing	employing	reused	components	and	(3)	implementation	of	the	reuse	process.		Current	demolition	practices	and	state	of	art	in	Singapore	First,	we	study	in	detail	the	flow	of	materials,	processes	and	related	stakeholders	in	Singapore,	with	focus	on	their	economic	and	environmental	dimensions.	The	objective	 is	to	understand	existing	practices	and	 identify	areas	 of	 opportunity	 to	 procure	 used	 building	 components	 that	 today	 end	 up	 in	 landfill	 with	 a	 cost	 to	 the	demolition	contractors.	The	research	was	done	through	interviews	with	the	main	stakeholders,	site	visits,	and	literature	review.		Research	reveals	that	although	Singapore	has	a	high	rate	of	concrete	and	metal	recycling,	reuse	practices	are	negligible.	 The	main	 reason	 is	 the	 lack	 of	market	 for	 reused	 components	 due	 to	 the	 perceived	 decrease	 in	construction	quality	within	a	very	expensive	 real	estate	market,	 the	preference	 for	 sleek	new	buildings,	and	the	concentration	of	construction	activities	in	large	public	and	private	developers.		3		The	 process	 of	 demolition	 largely	 remains	 a	 machine	 intensive	 effort	 with	 manual	 sorting	 of	 low	 value	components.	Once	a	building	is	designated	for	demolition,	various	demolition	contractors	participate	in	a	bid	to	pay	for	building	demolition.	A	qualitative	estimation	of	metal	scrap	in	building	forms	the	basis	for	negative	or	positive	cost	of	demolition	for	the	building	owner.	If	the	scrap/metal	components	are	high,	most	likely	the	owner	 will	 get	 paid	 for	 building	 demolition.	 Keeping	 heavy	 and	 voluminous	 nature	 of	 construction	 and	demolition	waste	 in	mind,	 the	National	Environment	Agency	of	Singapore	 follows	a	punitive	measure	 for	 its	reduction	with	landfill	gate	fee	of	S$77/Ton.	Under	such	circumstances,	the	construction	and	demolition	waste	is	downgraded	for	application	at	 land	reclamation	sites	or	as	hard	core	alternative	for	bottom	layers	 in	road	construction.	 Although	 the	 National	 Environment	 Agency	 estimates	 99%	 recycling	 of	 Construction	 and	demolition	waste,	the	actual	percentage	of	clean	concrete	recovered	and	recycled	into	structural	concrete	is	hard	to	estimate	but	most	likely	remains	substantially	lower.	Though,	Singapore	demolition	guidelines,	SS	557	(2010),	 provide	 systematic	 approach	 for	 building	 demolition	 to	 maximize	 resources	 recovery,	 its	implementation	remains	largely	invisible.	The	major	reason	is	higher	labor	cost	involved	in	resource	recovery,	absence	of	reuse	market	and	strict	timeline	to	complete	demolition.	Lack	of	market	in	many	ways	seems	big	hurdle	in	achieving	efficient	reuse	of	building	components.	Current	demolition	practices	target	metal	recovery	as	sole	source	of	value.	Due	to	Singapore’s	Green	Mark	requirements	(the	local	building	rating	tool),	some	of	the	 portion	 of	 concrete	waste	 reaches	 recycling	 plants	 to	 become	 recycle	 concrete	 aggregates	 (RCA)	which	mostly	 find	 low	value	applications	 in	 temporary	 construction.	Due	 to	 lack	of	 recycling	 facility	 and	a	 cost	 for	waste-to-energy	plants,	glass	and	wooden	components	are	mostly	crushed	and	mixed	 into	construction	and	demolition	debris	or	instead	sent	to	a	incineration/waste-to-energy	plant.	Occasionally	informal	collectors	take	out	good	conditioned	wood	elements	and	furniture	for	sale	in	nearby	cities.	Various	piping	and	air-condition	ducts	are	usually	treated	as	metals	and	recovered	after	demolition.		To	briefly	summaries	the	building	demolition	process,	demolition	machines	are	landed	on	top	floor	of	building	after	creating	a	passing	way	 for	vehicles	 (Image	2).	A	 top	down	approach	 is	 followed	 to	minimize	 the	space	requirement	 for	 logistics.	 Lift	 holes	 serve	 as	 a	 passage	 for	 building	 debris	 to	 ground	 floor	 where	 debris	 is	crushed	 to	 remove	 metal	 rebar	 and	 other	 metallic	 components.	 To	 extract	 smaller	 magnetic	 metal	components,	 a	magnet	 is	 used	 in	 the	 presence	 of	 workers	 who	 remove	 any	 non-magnetic	metal	 that	may	remain	at	 the	pile	of	debris.	After	metal	extraction,	debris	 is	 sent	either	 to	 landfill	or	 land	 reclamation	sites	while	 good	 quality	 concrete	 from	 columns	 and	 beams	 is	 sent	 for	 recycling	 into	 RCA.	 Current	 practice	 of	demolition	remains	largely	devoid	of	second	life	of	materials	in	the	form	of	reuse.		Thus,	 current	 demolition	 practices	 provide	 an	 opportunity	 to	 reuse	 building	 components	 for	 high	 level	applications	 in	 low-cost	housing.	 If	done	at	a	 large	scale,	urban	mining	of	building	components	 in	developed	cities	can	greatly	improve	the	efforts	for	achieving	adequate	urban	housing	in	developing	countries.		To	implement	this	process,	a	number	of	challenges	need	to	be	overcome.	The	window	of	time	when	materials	can	be	recovered	is	very	short,	around	one	to	two	weeks	at	the	beginning	of	the	demolition	process.	Today,	demolition	contractors	usually	invite	“acquaintances”	enter	the	site	and	“scavenge”	for	furniture	at	minimum	cost.	 Beyond	 this	 timeframe,	 recovery	 activities,	 which	 can	 entail	 delays	 in	 the	 demolition	 process,	 are	considered	unreasonable.	Low-cost	housing	using	reused	components		Second,	we	study	how	to	design	low-cost	housing	units	with	proper	habitability	levels	and	minimum	cost	using	discarded	materials.	We	 are	 currently	 working	 in	 collaboration	 with	 Habitat	 for	 Humanity	 in	 the	 design	 of	prototypical	 unit	 for	 Batam,	 Indonesia,	 a	 city	 15km	 from	 Singapore	 where	 Habitat	 for	 Humanity	 has	 been	conducting	significant	construction	work.		Our	first	step	is	to	study	how	recovered	materials	can	be	used	in	low-cost	units	and	how	to	facilitate	material	recovery	within	the	short	window	of	time	that	demolition	practices	can	offer.	As	a	case	study,	we	studied	the	reusability	of	a	building	soon	 to	be	demolished,	 the	Rochor	Centre	 in	Singapore.	We	proposed	and	 tested	a	process	to	quickly	survey	the	building	using	3d	point	cloud	scanning,	which	aims	to	simplify	the	identification	of	the	existing	material	stock.	This	is	crucial	to	expedite	the	tight	recovery	process	and	to	facilitate	the	design	of	low-cost	units.	The	actual	survey	of	the	building	took	two	hours	on	the	site,	and	produced	a	3d	model	that	was	used	to	identify	useful	parts	and	locate	components	to	be	recovered	for	our	low-cost	housing	units	(see	Images	3	and	4)		4		Materials	that	are	suitable	to	be	recovered	include:	windows,	doors,	kitchen	cabinets,	bathroom	and	kitchen	fixtures,	 and	 surface	 finishing	 in	 good	 condition.	 In	 addition,	 concrete	 components	 such	 as	beams,	 columns	and	slabs,	if	carefully	taken	apart,	can	also	be	reused.		The	 second	 step	 is	 the	 design	 of	 housing	 units	 that	 can	 be	 tailored	 to	 the	 particular	 characteristics	 of	 the	recovered	components.	Designing	using	recovered	materials	presents	challenges	to	designers	due	to	the	non-standard	nature	of	materials	 [5,	 6].	 As	 a	 benchmark,	we	based	our	 design	 in	 a	 prototypical	 unit	 for	 Batam,	Indonesia,	by	Habitat	for	Humanity	(see	Image	5).	Our	design	follows	its	basic	layout,	replacing	new	materials	with	 reused	 components	 from	 the	 Rochor	 Centre.	 Image	 6	 displays	 a	 design	 we	 propose	 for	 the	 low	 cost	housing.			Implementation	The	implementation	of	the	reuse	process	involves	a	number	of	organizational	and	logistic	challenges.	We	are	currently	 working	 towards	 understanding	 and	 overcoming	 those	 challenges	 by	 designing	 and	 building	 a	prototypical	unit.		As	today,	we	have	established	a	new	bridge	between	supply	and	demand	for	reused	components:	demolition	contractor	Aiksun	Engineering	and	Demolition	Pte	Ltd	on	the	supply	side	and	with	Habitat	for	Humanity	on	the	demand	side.	Both	parties	have	stated	 their	willingness	 to	 facilitate	 the	process.	Our	work	at	SUTD	 involves	coordination,	design	and	execution.		We	 anticipate	 a	 number	 of	 logistic	 needs:	 A	 small	 warehouse	 space	 in	 Singapore,	 transportation	 from	 the	demolition	 site	 to	 the	assembly	 space	and	 to	 the	 final	destination,	 and	 construction	 in	 the	 final	 location.	 In	terms	 of	 cost,	 uncertainties	 are	 still	 high.	 Cost	 of	 building	 components	 involve	 labor	 to	 disassemble	 and	transportation	 from	 the	 site	 to	 the	 assembly	 space.	 In	 addition,	 new	 construction	materials	 and	 labor	 are	needed	 in	 the	 construction	 site.	 We	 aim	 to	 have	 a	 clear	 understanding	 of	 the	 actual	 costs	 through	 the	prototypical	unit.	Conclusion	This	 research	 contributes	 with	 strategies	 to	 produce	 very	 low-cost	 housing	 units	 using	 reclaimed	 building	components,	focused	on	the	functional,	aesthetic	and	economic	aspects.	In	this	way,	it	proposes	and	supports	an	 alternative	 approach	 to	 the	 urgent	 urban	 housing	 problems	 through	 sustainable	 end-of-life	 buildings	management.		We	 have	 already	 tested	 the	 feasibility	 of	 this	 approach	 in	 theory,	 by	 cooperating	 with	 the	 relevant	stakeholders,	surveyed	a	real	demolition	site	and	designed	a	possible	unit.	In	addition,	we	designed	a	process	to	facilitate	the	survey	of	building	stock	to	be	demolished,	the	recovery	of	components	and	the	design	of	new	units	using	a	fast	3D	point	cloud	scanning.	We	tested	this	process	by	scanning	the	Rochor	Centre	in	Singapore,	cataloguing	useful	components	and	designing	a	unit.		To	 implement	 this	project,	we	 identified	a	 large	number	of	practical	 concerns	 including	costing	and	 logistics	that	 we	 aim	 to	 answer	 through	 actual	 construction	 of	 a	 prototypical	 unit	 in	 the	 next	 year,	 including	transportation	 of	 materials,	 assembly	 space	 in	 Singapore	 and	 procurement	 of	 new	 materials	 and	 final	assembly	on	site	in	Batam,	Indonesia.	Success	of	such	an	attempt	may	facilitate	to	open	up	a	new	direction	for	second	life	of	building	components	in	general	and	urban	contribution	for	low	cost	housing	in	particular.	Acknowledgement	The	 authors	 acknowledge	 contribution	 of	 Denise	 Nicole	 Lim	 Jeay	 Yee	 and	 Bai	 Xueni,	 students	 under	 the	Singapore	University	of	Technology	and	Design	Undergraduate	Research	Opportunity	Program	(UROP),	in	this	project.	Authors	thank	Habitat	for	Humanity	Singapore,	Aiksun	Demolition	and	Engineering	Pte.	Ltd.,	National	Environment	Agency,	Building	and	Construction	Authority	and	Housing	Development	Board	Singapore	for	their	support	and	inputs	in	research	work.				5		References	1. 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. 	Graphic	Work,	Images			Image	1.	Diagram	of	current	material	flow	in	Singapore	(left)	and	of	target	flow	after	intervention	(right).				6			Image	2.	Typical	demolition	site	in	Singapore.	Image	Credits:	Mohit	Arora			Image	3.	3d	point	cloud	scanning	of	the	Rochor	Centre	in	Singapore.	Image	Credits:	Felix	Raspall			7					Image	4.	3D	scan	pointcloud	of	Rochor	Centre	in	Singapore.	Image	Credits:	Felix	Raspall				Image	5.	Prototypical	low-cost	housing	design	for	Batam,	Indonesia	by	Habitat	for	Humanity.	Image	Credits:	Habitat	for	Humanity	Singapore		8		Image	6.	Design	for	very	low-cost	housing	using	components	from	the	Rochor	Center	Singapore.		

Building from End-of-Life: An Alternative Approach for Low-Cost Urban Housing

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Building from End-of-Life: An Alternative Approach for Low-Cost Urban Housing

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