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Influence of construction and demolition waste management on the environmentalimpact of buildings
Andr Coelho, Jorge de Brito
Department of Civil Engineering and Architecture, Instituto Superior Tcnico, Universidade Tcnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
a r t i c l e i n f o
Article history:
Received 1 February 2011Accepted 24 November 2011
Available online 17 December 2011
Keywords:
Construction and demolition waste
Life Cycle AnalysisWaste management options
a b s t r a c t
The purpose of this study is to quantify comparable environmental impacts within a Life Cycle Analysis(LCA) perspective, for buildings in which the first (Materials) and last (End of Life) life cycle stages are
adjusted to several waste/material management options. Unlike most LCAs, the approach is top-downrather than bottom-up, which usually involves large amounts of data and the use of specific software
applications. This approach is considered appropriate for a limited but expedient LCA designed tocompare the environmental impacts of different life cycle options.
Present results, based on real buildings measurements and demolition contractor activities, show that
shallow, superficial, selective demolition may not result in reduced environmental impacts. Calculations
actually show an increase (generally less than 5%) in most impact categories for the Materials and End ofLife stages because of extra transportation needs. However, core material separation in demolition oper-ations and its recycling and/or reuse does bring environmental benefits. A reduction of around 77% has
been estimated in the climate change impact category, 57% in acidification potential and 81% in thesummer smog impact (for the life cycle stages referred).
2011 Elsevier Ltd. All rights reserved.
1. Introduction
The work described here stems from a wider study which anal-yses selective and traditional demolition practices in technical andeconomic terms. It is also linked with construction and demolitionwaste (CDW) generation (Coelho and de Brito, 2010a) and distribu-tion quantification in Portugal (Coelho and de Brito, 2010b).
The work as a whole is an analysis of the technical, economicand environmental viability of a large-scale fully-developed CDWrecycling plant in Portugal. It is a tentative comparative analysisof the environmental impacts of different options in CDW manage-
ment at the end-of-life stage of a buildings life cycle. The purposeis to quickly quantify the environmental effects of applying decon-
struction techniques and recycling options by incorporating theseprocesses into the environmental impact of producing materials
and transporting them to site (closing the cycle).The environmental impact of a buildings life cycle has been
researched widely in recent years by various authors (Junnila,2004b; Pinto, 2008; Balazs et al., 2001; Pascualino et al., 2008;
Blengini, 2006, 2008; Xiaodong et al., 2010; Krogmann et al.,2009; Schuer et al., 2003). Building projects not intended for re-search purposes but which include LCA approaches in the designphase are very few, however (Hes, 1998, 2001a,b). One of the major
barriers to this is the reluctance to move design time lines toaccommodate the extra time needed for an LCA, even though thismight offer clear financial and environmental benefits (Hes,
2001a).Most of these studies have adopted a bottom-up approach
using databases with embodied energy and emissions of severalconstruction materials (Gonzlez and Navarro, 2005; Peuportier,
2001; Junnila, 2004b). These environmental impact analyses ofbuildings rely heavily on drawings, specifications and/or data fromthe actual buildings.
This approach is generally adequate when information on
building quantities (bill of quantities), final drawings and appropri-ate construction products environmental impact databases is
available, bearing in mind the location of the buildings in relationto building materials suppliers and waste management operators.
When these conditions are met, with high levels of transparency(clear definition of system boundaries, clear allocation methods,no mixing of data from different sources, etc.), along with coherentend-of-life and recycling considerations, present-day LCA software
tools will provide reasonably accurate environmental impactresults, reproducible to about 10% (Peuportier & Putzeys, 2005).Neglecting some or all of these requirements will naturally makeLCA unreliable, or at least questionable.
This is calledthe process-based LCAand it enables very specificanalysis, although it requires detailed information, which makes ittime consuming and costly. In fact, the longer the supply chain
0956-053X/$ - see front matter 2011 Elsevier Ltd. All rights reserved.doi:10.1016/j.wasman.2011.11.011
Corresponding author. Tel.: +351 218443659; fax: +351 218443071.
E-mail address:jbrito@civil.ist.utl.pt(J. de Brito).
Waste Management 32 (2012) 532541
Contents lists available at SciVerse ScienceDirect
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http://dx.doi.org/10.1016/j.wasman.2011.11.011mailto:jbrito@civil.ist.utl.pthttp://dx.doi.org/10.1016/j.wasman.2011.11.011http://www.sciencedirect.com/science/journal/0956053Xhttp://www.elsevier.com/locate/wasmanhttp://www.elsevier.com/locate/wasmanhttp://www.sciencedirect.com/science/journal/0956053Xhttp://dx.doi.org/10.1016/j.wasman.2011.11.011mailto:jbrito@civil.ist.utl.pthttp://dx.doi.org/10.1016/j.wasman.2011.11.0118/13/2019 Coelho Brito
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This option has naturally meant that only a scenario compari-son has been possible, and not an absolute environmental impact
value ranking. Calculations have therefore been made in the origi-nal environmental impact parameter units (kg CO2eq/m
2, kgSO2eq/m
2 and so on) but the resulting values are not used strictlyto obtain environmental impact figures, in those same units, for
buildings in other contexts.
However, considering all data retrieved from real buildings anddemolition operations, the purpose is to give a representative im-age of Portugal as a whole, as far as End-of-Life and Materials life
cycle stages of existing buildings over 30 years old, chosen usingthe criteria established in (Coelho and de Brito, 2010a) areconcerned.
InJunnila (2004a)a detailed environmental LCA was performed
for all life cycle stages in the buildings under analysis, althoughscenarios involving deconstruction were not included. Among theresulting conclusions were:
Similar results are to be expected in housing and services build-ings, from a life cycle environmental impact point of view.
Different services buildings, designed by different teams, built
by different contractors and occupied by different organiza-tions, show a similar pattern for each life cycle stage proportionwithin the buildings global environmental impact.
The end-of-life stage impact is generally below 3%, which is
small compared with the global impact in all the analysed cat-egories. But the differences found in the inclusion of recycledmaterials can lead to significant changes in the summer smogand heavy metals categories (38% and 20% respectively).
Furthermore, Junnilas work used case studies chosen in a ratio-nale of replication to obtain similar results for buildings with sig-nificantly different characteristics. This means that average
values (here taken from Junnilas case studies) can be used to esti-mate the environmental impact distribution over the life cycle of ageneralized housing or office building to compare scenarios which
may influence the environmental impacts of one or more life cyclestages.
For this comparison, some LCAs use weighting methodologies toreach single score indexes (Blengini et al., 2010; Mithraratne andVale, 2004), which may help decision-makers to read and easily
interpret LCA results. However, the comparison presented in thisstudy does not attribute different relative importance factors tothe impact categories, which were chosen according to Junnila(2004a).
The impact categories are: climate change (kg CO2eq/m2), acid-
ification (kg SO2eq/m2); summer smog (kg C2H4eq/m
2); nitrifica-tion (kg PO4eq/m
2); and heavy metals (kg Pbeq/m2). They result
from the emission of a wide array of substances, all of which areknown to be important pollutants. Natural resources extraction
and waste generation have not been considered explicitly, but itnaturally follows that waste management practices involving the
recycling and/or reuse of materials/components lead to less extrac-tion of raw materials and less waste generation, since these prac-tices limit new raw materials use.
Importance factors were not used in relation to impact catego-
ries because of the subjectivity and controversy implied (Craighill& Powell, 1999).This aspect is aggravated by the many variablesat stake which may give rise to the higher or lower relative impor-tance of certain factors over others: the ecological sensitivity of
certain regions, human concerns about that region, stakeholdersinterests/opinions, time constraints, economic reasons, amongothers.
By not applying these factors this study attributes equal impor-
tance to all impact categories under consideration.
A snapshot of the global impacts calculated in (Junnila, 2004a)for each building is presented inTable 1. Averaging the life cycle
impact proportions for the buildings referred to inTable 1(also ta-ken directly from Junnilas work) will provide the above general-ized/reference buildings life cycle stage average impacts, as usedhere, as both percentage proportions and environmental impact
units (Table 2).
As an example, the climate change impact factor of 271 kgCO2eq/m2 for the generalized building Materials stage was ob-
tained as the result of a 7.3% share of the 3700 kg CO2eq/m2 global
average climate change impact presented in Table 1. All otherTable 2figures were obtained in the same way.
The average life-cycle shares are calculated from (Junnila,2004a), from the buildings A, B and C individual shares. Only the
Materials and End-of-Life cycle stages were considered in the anal-ysis, mainly to eliminate differences in impacts that may occur inthe operational phase of buildings located in Finland and Portugal.
These differences in impacts may appear for several reasons,such as climatic differences, building features and living habits.However, results including the complete life cycle (even thoughwith basic data sourced from Finnish LCA case study) are also
shown so as to give an idea of the possible impact of the proposedMaterials and End-of-Life scenarios when all life cycle stages areaccounted for (Table 12).
Having characterized the generalized reference building in
terms of environmental impacts, scenarios can now be defined.Five cases were considered, depending on end-of-life managementactivities: traditional demolition with landfill or recycling anddeconstruction, the material quantities landfilled, and different op-
tions for incorporating recycled or reused materials in new con-struction. These scenarios are summarized inTable 3.
Demolition/end-of-life environmental consequences are mainlyconditioned by transportation, even though the impacts of direct
demolition activities and materials transportation have both beenconsidered in the specified scenarios. In fact, according toBlengini(2006), demolition environmental consequences only account for
7% of total demolition/end-of-life stage activities, the rest arisesfrom transportation.
Even though Blenginis figure applies only to energy consump-tion, it is here assumed valid for other impact categories since ithas been demonstrated that around 80% of all emissions into the
atmosphere derive from energy production (International EnergyAgency, 2005).
Different demolition procedures, from traditional demolition tototal piece-by-piece deconstruction, will naturally lead to different
energy consumption and waste generation patterns from the activ-ities themselves, but given the relatively small importance of thissub-stage in life cycle environmental impacts, the differences were
ignored.The demolition activity impacts for scenario 1 were therefore
considered constant for all scenarios. Transportation impacts, withmuch higher relative importance, were specifically considered for
each scenario, depending on recycling and reuse percentages.Fifteen demolition cases were analysed to establish a relation-
ship between the percentage of materials sent for recycling andtransportation distance, with information supplied by a specialized
contractor. This data is given by a sample of this contractors nor-mal activity, which involves selective demolition, demolition, on-site separation and transport.
Demolished buildings comprise houses, schools, office buildings
and commercial sites. Manual labour is generally used for theselective demolition of accessible covering elements such as woodfloors, doors, windows, cabinets and ceilings. The core dense struc-tural materials, i.e. bricks, stone and concrete, plus various at-
tached materials such as structural wood frames, fixed sanitary
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Table 1
Global environmental impacts obtained by (Junnila, 2004a), by impact category and by building analyzed.
Impact category Unit Building A Building B Building C Average
Climate change kg CO2eq/m2 4700 3100 3300 3700
Acidification kg SO2eq/m2 15.1 8.5 9.8 11.1
Summer smog kg C2H4eq/m2 2.1 1.6 2.3 2.00
Nitrification kg PO4eq/m2 1.6 1 1.3 1.30
Heavy metals kg Pbeq/m2 0.0021 0.001 0.001 0.0014
Notes:(1) All life cycle impact phases are included, from Materials (extraction, production and transport) to End-of-Life (demolition and waste management operations); (2)
Life span considered: 50 years; (3) Main climate conditions: Finland.
Table 2
Environmental impacts, by category and life cycle stage, for the average reference building.
Impact category Unit Life cycle stages reference case generalized building
Materials Demolition/end-of-life Total
Quantity % Quantity % Quantity %
Climate change kg CO2eq/m2 271 7.3 37.0 1.0 308 8.3
Acidification kg SO2eq/m2 1.26 11.3 0.37 3.3 1.63 14.7
Summer smog kg C2H4eq/m2 0.51 25.3 0.05 2.7 0.56 28.0
Nitrification kg PO4eq/m2
0.13 10.0 0.06 4.7 0.19 14.7Heavy metals kg Pbeq/m2 0.00057 42.0 0.00003 2.3 0.0006 44.3
Note:Percentages of total life-cycle environmental impact, for each impact category.
Table 3
End-of-life and materials life cycle stages scenario.
Scenario Short description Notes/observations/assumptions
1 Complete demolition of building and transport of materials to
landfill
1. Environmental impacts are considered equal to those of the generalized reference
building.a However, no extra transportation distance was added (due to recycling), since
this scenario does not involve recycling
2 Selective demolition of non-structural elements (soft
stripping), followed by complete demolition of all other
materials
1. Elements removed during soft stripping: mechanically fixed coverings, water supply
and waste water drainage pipes, electrical cables, doors, windows. Destination:
recycling2. Elements destroyed during traditional demolition: masonry walls, structural support
elements (concrete, steel and wood). Destination: landfill.
3. Demolition (not transport) environmental impacts are considered equal to those
incurred by the generalized reference building
4. Environmental impacts due to transportation of materials for recycling are calculated
from scenario 1 basis (using the transportation distance enlargement factor)
5. Extra environmental impacts due to recycling operations are accounted for as a per-
centage of the original (scenario 1) impacts with the materials supply (as shown in
Table 9)
6. Input data from housing buildings measured in (Coelho and de Brito 2010a)3 Deconstruction of non-structural elements, followed by
complete demolition of all other materials
1. Demolished structural elements are sent to recycling, whenever possible (depends on
each real case situation)
2. Demolition (not transport) environmental impacts are considered equal to those
incurred for the generalized reference building
3. Total recycled aggregate quantity included in new construction is limited to 10% (only
general fills) of the total CDW generated from deconstruction and demolition of the
building parts
4. Input data from services buildings measured in (Coelho and de Brito 2010a), along with12 other real cases of demolition operations performed by a contractor
4 Full deconstruction, sending all materials to recycling 1. Hazardous materials are landfilled (in a controlled way)
2. Recovered masonry and concrete are recycled and used to produce new masonry bricks
and concrete
3. All other materials are recycled and used in new construction materials4. The same input data as in scenario 2 is used
5 Full deconstruction, sending all materials which cannot be
reused to recycling
1. Hazardous materials are landfilled (in a controlled way)
2. Recovery for reuse purposes do not cause significant environmental impacts (extra
impacts due to recovering activities are ignored), when compared to recycling impacts
3. Extra transportation needed for material reuse refers exclusively to these materials (not
mixed with those being recycled), assuming an average distance equal to where the
landfill is located
4. Of all recovered materials aimed for reuse, only 50% is actually reusable (the rest is
recycled)
5. The same input data as in scenario 2 is used
a
In the generalized reference building no allocation of emissions was assumed for the future products that are made from recycled building materials. This means that noreduction in the environmental impacts of the materials life cycle stage was considered. This derives directly from (Junnila, 2004a).
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elements, water and drainage pipes and roof shingles are demol-ished in a more traditional fashion, using mechanical equipment
(Coelho and de Brito, 2011).Transportation distances were calculated for each case and
material managed, given its destination. These destinations arenaturally selected by the contractor to be as close as possible to
the worksite, for optimization and cost savings; for our contractor
and for jobs in the Lisbon area, the distance will generally be lessthan 50 km).However, and especially when sending materials to be recycled,
local operators are not always available (e.g.: recycling operatorsfor wood, glass and some oil contaminated materials), which canimply transportation distances over 5 times more than the rest ofthe materials average transportation distance.
A sample table is shown (Table 4) with the quantities, destina-tions and transported distance related to a certain demolition job.A total transportation distance was derived from this, to be com-
pared with a reference (hypothetical) situation where all materialswould be sent to landfill. In the calculations, transported volumesare calculated from loose material densities, listed in Table 6.
Transportation distance in the latter case depends heavily on
the selected waste operator, and so its choice has been based onthese criteria:
1. The waste operator must be located within 100 km of the site,
or be the nearest waste operator otherwise.2. The waste operator must be a generalist (i.e. accepting several
types of CDW).3. After points 1 and 2 are considered, the waste operator chosen
will be the one to which, in reality, a greater distance was cov-ered (measured by the sum of all distances listed to each oper-ator which check criteria 1 and 2).
Criterion item 1 is used to give preference to close range generaloperator locations, which are generally (but not always) within100 km. Criterion item 2 excludes specialized operators (e.g.: glass
or wood only recyclers), which cannot receive loads of co-mingledCDW materials. The final criterion item selects the operator whichin practice, for each job and after the selection implied by items 1and 2, has been preferred by the contractor as far as total transportdistance is concerned.
Table 5was built up by applying these criteria and the methodused to compileTable 4to all remaining real demolition cases. Anaverage transportation magnification factor (Mt) could then be de-rived, along with an averaged percentage of recycled material that
could be used in new construction. Mtis calculated by dividing thetotal transportation distance for each real example (with its recy-cling options) by the distance calculated for all materials being
sent to landfill.Plotting the relationship Recycling % vs. Mtresults inFig. 1, from
which a quadratic function is fitted, with a good approximationfactor (R2 = 0.86). From this function it is now possible to estimate
Mt, for each scenario (using each recycling ratio as indicated inTa-ble 7), which will affect their environmental impacts considerably.
Demolition/end-of-life environmental impacts are then quanti-fied based on the generalized building impacts, shown in Table 2.
Table 8 presents these values, for each impact category and foreach scenario, using each Mt value as a proportion factor, derivedfrom the equation presented inFig. 1.
As these scenario impacts all derive from the generalized build-
ing impacts described above, which implies a 27% recycling rate(and a complementary 73% landfill rate), then obtaining transpor-tation impacts for scenario 1 involves dividing the generalizedbuilding transportation only impacts by Mt (scenario 1 implies
0% of materials sent to recycling), while for the other scenarios itwill mean multiplying by Mt.
Besides the direct impact of demolition activities and materialtransportation at the end-of-life stage, other environmental effects
must be considered which result from the recycling processesthemselves; these will depend on the amount sent for recycling,in each scenario. As for reuse, certainly some impacts are intrinsicto the activity (apart from transportation), e.g.: cutting wood,
cleaning masonry bricks, storing material.
This aspect has been ignored in this analysis since the effectsare generally weaker than those inherent to recycling activities(Craighill & Powell, 1999; Gao et al., 2001). These references deal
with energy consumption and the broad environmental impact ofreusing scenarios. However, the results reported in Craighill &Powell (1999) consider transportation and comprise an averageof several case studies, mostly related to mineral extraction and
road maintenance.In spite of this, the reuse scenario in that study leads to an aver-
age reduction of almost 70% in environmental impacts compared
with the scenario involving 50% landfill and 50% recycling. In(International Energy Agency, 2005) reusing activities have beenassumed to add no energy consumption, in a direct comparisonwith recycling activities.
Data fromBlengini (2008)was used to quantify the extra im-pacts caused by recycling. According to this study, certain net envi-ronmental benefit reductions may be expected from recyclingoperations despite some additional impacts resulting from the pro-
cesses used to recycle aggregate and steel products.An average of three environmental impact indicators was calcu-
lated for the extra impacts from recycling, resulting in 17% foraggregates and 39% for steel products. These extra impact percent-
ages mean that, whatever the environmental impact reductionbrought about by recycling, the final impact of the considered lifecycle stages including recycling will be 17% and 39% higher foraggregate and steel mass respectively.
Knowing the quantities of materials used for the measuredbuildings/demolition examples in the listed scenarios (Table 3),particularly the aggregate and metals generated, these percentages
are applied to give the overall extra environmental impact percent-ages presented inTable 9.
The direct reduction of environmental impacts in the materialslife cycle stage equals the percentage of recycled (plus reuse, ifany) material in a certain scenario, as summarized in Table 7. In
other words, a simple subtraction takes the first into account bydeducting the equivalent environmental impacts of the new mate-rials initially planned for each scenario, but considering that somematerial sent for recycling may not be used again in building
construction (factor u as described in the equations below).The resulting figure is then affected by the extra recycling oper-
ations impact percentages described above. For scenario 3, how-
ever, even though most of the materials are sent to landfill, itwas assumed that when aggregates can be recycled only 10% are
used in new construction. This was to account for some generalbulk fills, which are relatively common practice today.
As for reuse (only in scenario 5), only part can actually be re-used and the rest is sent for recycling. This part is considered tobe 50%, based on published data (Guy, 2000, 2005; Southworth,2009).
Environmental impact values for the materials life cycle stagewere therefore finally calculated using the following expressions:
Scenario 2 : IC2i IC1i 1
PC2r uC2=100
100
! 1
AC2
100
! 1
In which:IC2i environmental impact value, for category i, in sce-nario 2; IC1i environmental impact value, for category i, in scenario
1;PC2
r material percentage sent for recycling, in scenario 2;uC2
weighted average, over waste weight, of possible recycled material
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Table 4
Total transportation distance, with and without recycling options (one of 15 real examples).
EWL Code Name Weight
kg
Destination % of
total, in
weight
Waste
operator
Site distance,
km
Volume
m3
Number
of
journeys
Transportation
distance, km
Usa
con
prorecy
With recycling options
170107 Mixture of concrete 23020 Landfill 10.74 Citri 48 16 1 48
170201 Wood 97220 Recycling 45.38 Ecociclo 210 324 17 3570 Yes
170202 Glass 3680 Recycling 1.72 Vidrologic 234 11 1 234 Yes
170405 Iron and steel 10380 Recycling 4.84 Palmela
recycling
centre
46 12 1 46 Yes
170407 Mixed metals 14440 Recycling 6.74 16 1 46 Yes
170603 other insulation materials
containing dangerous
substances
7940 Landfill 3.71 Quimitcnica 37 611 32 1184
170604 Glass wool 8520 Landfill 3.98 Citri 48 655 34 1632170903 CDW with dangerous
substances
23440 Landfill 10.94 Quimitcnica 37 156 9 333
200101 Paper and cardboard 3200 Recycling 1.49 A.S Simes 27 32 2 54 Yes200301 Mixed municipal waste 17520 Landfill 8.18 Citri 48 117 7 336
200121 Fluorescent tubes and other
mercury-containing waste
130 Recycling 0.06 Ambicare 48 0 1 48 Yes
200136 Discarded electrical and
electronic equipment
920 Recycling 0.43 Ambitrena 48 6 1 48 No
200138 Wood 3840 Recycling 1.79 Ecociclo 210 13 1 210 Yes
EWL Code Name Weight
kg
Destination Waste
operator
Site distance,
km
Average
loose waste
density, kg/m3
Volume
m3Number
of
journeys
Transportation
distance, km
Without recycling options
170903 Construction anddemolition wastes
containing dangerous
substances
214.250 Landfill Citri 48 404 531 28 1344
Total transportationdistance, with
recycling options, km
7789
Total transportation
distance, without
recycling options, km
1344
Notes:The number of journeys is calculated using standard 19.3 m3 sized trucks; Volumes are calculated, from weights, using loose material density values shown inTable 6
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use in new construction; AC2 recycling operations averaged extra
environmental impact, in percentage.Eq. (1) applies to scenario 3, using a different percentage for
recycling materials and so a different value for Mt. As for scenario4, since all materials are considered to be incorporated into new
construction, the uC factor equals 100% and can be eliminated,and so Eq. (1) becomes:
IC4i IC1i 1
PC4r100
! 1
AC2
100
! 2
Finally, for scenario 5, which includes a certain amount of reusedmaterials, the equation is simply updated as follows:
IC5i IC1i 1
PC5r pC5r
100
! 1
AC2
100
! 3
In whichpC5r equals the reused material percentage, for scenario 5.
4. Results and conclusions
The results for each scenario are presented in Table 10. The
totals for each scenario make it possible to determine percentilevariations from scenario 1, representing a traditional approach of
landfilling all materials. Table 11 summarizes these variations,considering only the Materials and End of Life impact stages. Forgeneral perspective purposes only,Table 12shows the percentagevariations with regard to scenario 1, when all the life cycle stages
are accounted for.Table 10shows that the impacts share assigned to the Materials
phase is always over 75%, for any analysed impact category, in sce-narios 1 through 3. This is because, as replacement levels of input
materials is low in these scenarios
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sending more than 95% of the materials for recycling/reuse, signif-icant impact reductions are possible at the Materials stage. Impacts
resulting from this stage can even be lower than those comingfrom End-of-Life, assuming that these recycled materials are dulyreused in the construction of new buildings.
Table 10also shows that the highest total impact reductions oc-cur in the Heavy Metals (88%), Summer Smog (81%) and ClimateChange (77%) categories, when shifting from scenario 1 up to 5.These are the impact categories where the highest relative contri-butions of the Materials stage happen. So, when the latter under-
goes a sharp reduction due to inclusion of recycled/reusedmaterials in new construction, it affects mostly the highest con-tributors (in a proportional manner).
This global environmental impact comparison (based on a top
down LCA methodology) of building demolition scenarios withdifferent waste management approaches and recycled/reusedmaterials incorporation considerations in the materials life cycle
stage enables the following conclusions to be drawn:Soft-stripping, or the removal of non structural elements for
recycling, followed by a traditional demolition of all other materi-als and their removal to a landfill, will generally not imply any
environmental impact reduction in the impact categories studied.It may even slightly aggravate the environmental impact (scenario2 and some impact categories in scenario 3, although generally be-low 5%) because of longer transportation distances and because of
some extra recycling activity impacts. This is largely to do with themeans of transportation mostly used in the construction/demoli-tion industry: by road, with diesel trucks. The use of (net energysaving) biofuels, running electric vehicles and/or greater use of rail
transport could thus tip this environmental balance to the side ofsavings.
Medium to low material reuse percentage will not translate intoappreciable environmental impact reductions compared with the
equivalent recycled quantities (scenario 5 compared to scenario4). This is mainly because what really brings down environmental
y = -0,00054x2
+ 0,09360x + 1,45338R = 0,86588
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100Averagetransportationmagnificationfactor(Mt)
Recycling %
Fig. 1. Relationship between the recycling percentage and Mt.
Table 7
Recycling and reuse weight percentages for the scenarios under consideration.
Scenario Recycling (+ reuse), %
1 02 1.9
3 7.9
4 96.35 96.3
Note:Only scenario 5 includes reuse.
Table
8
Dem
olition/end-o
f-lifeenvironmentalimpactsforallcategoriesandscenarios.
Impact
category
Un
its
Genera
liz
edbuil
ding
Tota
l
Genera
liz
edbu
ilding
demo
litionon
ly
Transportation
on
ly
Tota
l
Lan
dfill73%;
Rec
yc
ling
27%
Genera
liz
ed
bu
ilding
Scenario
1
Scenario
2
Scenario
3
Scenario
4
Scenario
5
Scenario
1
Scenario
2
Scenario
3
Scenario
4
Scenario
5
C
limate
change
kg
CO
2eq
/m2
37
2.6
2
34
.4
9.5
15
.9
20
.9
51
.8
51
.8
12
.1
18
.5
23
.5
54
.4
54
.5
A
cidification
kg
SO
2eq
/m2
0.3
7
0.0
3
0.3
4
0.1
0
0.1
6
0.2
1
0.5
2
0.5
2
0.1
2
0.1
9
0.2
4
0.5
5
0.5
5
Summersmog
kg
C2
H4
eq
/
m2
0.0
53
0.0
04
0.0
50
0.0
14
0.0
23
0.0
30
0.0
75
0.0
75
0.0
17
0.0
27
0.0
34
0.0
78
0.0
78
N
itri
fication
kg
PO
4eq
/m2
0.0
61
0.0
04
0.0
56
0.0
16
0.0
26
0.0
34
0.0
85
0.0
85
0.0
20
0.0
30
0.0
39
0.0
89
0.0
89
H
eavy
meta
ls
kg
Pbeq
/m2
3.1
9E
-05
2.2
6E
-06
2.9
6E
-05
8.2
0E
-06
0.0
0001
1.8
0E
-05
4.4
7E
-05
4.4
72E
-
05
1.0
5E
-05
1.6
0E
-05
2.0
3E
-05
4.6
9E
-05
4.6
9E
-05
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impact is replacing raw materials with recycled and/or reused ele-ments, with very little being due to recycling or reuse. This is trueeven when considering that recycling entails more embodied im-pacts than reuse. The average reuse percentage calculated in the
present study is 25%, which is considered low but technicallyattainable, considering the typical buildings analysed (in the Portu-guese context). Greater impact reductions through reuse will re-quire much higher percentages of materials to be reused, which
could, in extremely favourable conditions, reach an average of50% as a theoretical maximum reusable material weight. Otherstudies have considered reuse percentages of 17% (Gao et al.,
2001) and as much as 100% (Craighill & Powell, 1999), resultingin a 11% lower energy consumption in the first case and a 68% aver-age environmental impact reduction in the latter (compared to anall-landfill standard options, concerning End-of-Life and Materialslife cycle stages). To reach the 50% level, however, for typical Por-
tuguese buildings over 30 years old, special care must be takenwith deconstruction. The careful extraction of wooden elements,masonry bricks and metal elements, for instance, cannot be doneby standard construction or demolition crews; experienced decon-
struction workers are needed who know exactly how to take thevaluable pieces apart and handle them with reuse in mind. Given
this reality it is currently better to direct policy efforts to increase
recycling and reinsert materials into the construction industry cy-cle than to make the extra effort to encourage materials reuse, ex-cept obvious examples such as clean, straight wooden girders, orwell-maintained sanitary equipment.
It is particularly important to try and reintroduce recycled or re-used materials into new construction, thereby helping to close thematerials cycle. This will help to reduce the summer smogand heavy metals impact categories, since these account for
Table 9
Extra environmental impact percentages due to recycling, for the selected scenarios.
Scenario Aggregates sent to
recycling/total
waste mass, %
Metals sent to
recycling/total
waste mass, %
Extra environmental
impact weighted
average, %
2 0.66 0.10 0.15
3 4.8 2.05 1.624 93.7 0.64 16.3
5 53.9 0.63 9.48
Table 10
Environmental impacts, by category and life cycle stage, for all scenarios.
Impact category Unit Materials Demolition/end-of-life Total
Life cycle stages scenario 1
Climate change kg CO2eq/m2 271 12.1 283
Acidification kg SO2eq/m2 1.26 0.12 1.38
Summer smog kg C2H4eq/m2 0.51 0.017 0.52
Nitrification kg PO4eq/m 0.13 0.02 0.15
Heavy metals kg Pbeq/m2 5.74E-04 1.05E-05 5.84E-04
Life cycle stages scenario 2
Climate change kg CO2eq/m2 267 18.5 285
Acidification kg SO2eq/m2 1.24 0.19 1.43
Summer smog kg C2H4eq/m2 0.50 0.027 0.52
Nitrification kg PO4eq/m 0.13 0.030 0.16
Heavy metals kg Pbeq/m2 5.64E-04 1.60E-05 5.80E-04
Life cycle stages scenario 3
Climate change kg CO2
eq/m2 252 24.3 277Acidification kg SO2eq/m
2 1.17 0.24 1.42
Summer smog kg C2H4eq/m2 0.47 0.035 0.51
Nitrification kg PO4eq/m 0.12 0.040 0.16
Heavy metals kg Pbeq/m2 5.34E-04 2.09E-05 5.55E-04
Life cycle stages scenario 4
Climate change kg CO2eq/m2 11.6 54.4 66.0
Acidification kg SO2eq/m2 0.054 0.55 0.60
Summer smog kg C2H4eq/m2 0.022 0.078 0.10
Nitrification kg PO4eq/m 0.006 0.089 0.09
Heavy metals kg Pbeq/m2 2.45E-05 4.69E-05 7.14E-05
Life cycle stages scenario 5
Climate change kg CO2eq/m2 10.9 54.5 65.3
Acidification kg SO2eq/m2 0.051 0.55 0.60
Summer smog kg C2H4eq/m2 0.020 0.078 0.10
Nitrification kg PO4eq/m 0.005 0.089 0.09
Heavy metals kg Pbeq/m2 2.30E-05 4.69E-05 7.00E-05
Note:The environmental benefits of recycling and reuse have been accounted for in the Materials phase, as prevented impacts.
Table 11
Global environmental impact percentage differences between scenarios 2 through 5
and scenario 1 (Materials and Demolition/end-of-life stages).
Impact category Scenario
2 3 4 5
Climate change 0.57 2.34 76.7 76.9
Acidification 3.02 2.49 56.7 56.9Summer smog 0.06 3.35 80.9 81.1
Nitrification 5.45 7.28 36.8 37.0
Heavy metals 0.78 5.01 87.8 88.0
Table 12
Global environmental impact percentage differences between scenarios 2 through 5
and scenario 1 (all life cycle stages).
Impact category Scenario
2 3 4 5
Climate change 0.045 0.19 6.08 6.10
Acidification 0.39 0.32 7.30 7.33Summer smog 0.016 0.91 22.0 22.0
Nitrification 0.65 0.86 4.36 4.38
Heavy metals 0.34 2.20 38.5 38.6
540 A. Coelho, J. de Brito / Waste Management 32 (2012) 532541
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considerable parts of the life cycle impact from the materials stage(25.3% and 42% respectively, for scenario 1), even though all other
categories will also see their impacts reduced.Even though climatic differences, building features and living
habits may differ between Portugal and Finland, which is wherethe basic data for this study was collected, the potential environ-
mental impact reduction scenarios studied with global life cycle
impacts are much lower than those observed in Table 11. Table12shows around 6% and 7% reductions in climate change and acid-ification related impacts for scenarios 4 and 5, but a figure of
almost 40% is reached for the Heavy Metals category.From a complete life cycle perspective, and in order to get any
obvious environmental impact reduction, especially in the climatechange and acidification categories, recycling will have to be raised
to above 90%, and efforts must be made to incorporate the result-ing materials into new construction. Recycling percentages of thisorder of magnitude can be achieved and have actually been ex-
ceeded in recent real demolitions (Bjerregaard et al., 2007; Kohler,2007a,b; Kohler & Davies, 2007).
Acknowledgements
Thanks are due to the FCT (Foundation for Science and Technol-ogy) for the postdoctoral research grant awarded to the first authorand to the ICIST IST research centre. Special thanks are due to
Brito Cardoso and Vera Teixeira, from Ambisider, RecuperaesAmbientais, SA.
References
Asif, M., Muneer, T., Kelley, R., 2007. Life cycle assessment: a case study of adwelling home in Scotland. Building and Environment 42 (3), 13911394.
Balazs, S., Antonini, E., Tarantitni, M., 2001. Application of Life Cycle Assessment(LCA) methodology for valorization of building demolition materials andproducts. Society of Photo-Optical Instrumentation Engineers (Eds.), SPIE the International Society for Optical Engineering 4193, 382390.
Bjerregaard, M., Shaw, H., Kohler, N. 2007. Recycling demolition arising at Barts andthe London Hospital. Waste & Resources Action Programme, Project Code
WAS006-002: (August 23, 2010).
Blengini, G.A., 2006. Life Cycle Assessment tools for sustainable development: casestudies for the mining and construction industries in Italy and Portugal.Doctoral Thesis in Mining Engineering, Instituto Superior Tcnico, TechnicalUniversity of Lisbon, Portugal.
Blengini, G.A., 2008. Life cycle of buildings, demolition and recycling potential: acase study in Turin, Italy. Building and Environment 44 (2), 319330.
Blengini, G.A., Di Carlo, Tiziana, 2010. The changing role of life cycle phases,subsystems and materials in the LCA of low energy buildings. Energy andBuildings 42 (6), 869880.
Blengini, Andrea, Garbarino, Elena, 2010. Resources and waste management inTurin (Italy): the role of recycled aggregates in the sustainable supply mix.Journal of Clearer Production 18 (1011), 10211030.
Carnegie Mellon University Green Design Institute (2008). Economic InputOutputLife Cycle Assessment (EIO-LCA), US 1997 Industry Benchmark model: (September 2, 2010).
Chen, T.Y., Burnett, J., Chau, C.K., 2000. Analysis of embodied energy use in theresidential building of Hong Kong. Energy 4 (26), 323340.
Coelho, A., de Brito, J., 2010a. Generation of CDW in Portugal. Waste Management &Research 29 (7), 739750.
Coelho, A., de Brito, J., 2010b. Distribution of materials in Construction andDemolition Waste in Portugal. Waste Management & Research 29 (8), 843853.
Coelho, A., de Brito, J., 2011. Economic analysis of conventional versus selectivedemolition a case study. Resources, Conservation & Recycling 55 (3), 382392.
Craighill, A., Powell, J., 1999. A Lifecycle Assessment and Evaluation of Constructionand Demolition Waste. Centre for Social and Economic Research on the GlobalEnvironment, CSERGE Working Paper WM 99-03, University of East Anglia, UK.
Dewulf, J., Van der Vorst, G., Versele, N., Jansens, A., Van Langenhove, H., 2009.Quantification of the impact of the end-of-life scenario on the overall resourceconsumption for a dwelling house. Resources, Conservation and Recycling 53(4), 231236.
Gao, W., Ariyama, T., Ojima, T., Meier, A., 2001. Energy impacts of recyclingdisassembly material in residential buildings. Energy and Buildings 33 (6), 553562.
Gonzlez, M.J., Navarro, J.G., 2005. Assessment of the decrease of CO 2emissions inthe construction field through the selection of materials: practical case study of
three houses of low environmental impact. Building and Environment 41 (7),902909.
Guy, B., 2000. Building deconstruction: reuse and recycling of building materials.Alachua County solid wastes management innovative recycling projectprogram, U.S.A: (February 26, 2010).
Guy, B., 2005. The optimization of building deconstruction for department ofdefense facilities: Ft. McClellan deconstruction project. University of SouthCarolina, U.S.A.: (January 23, 2010).
Hendrickson, C.T., Horvath, A., Lave, L., 1998. Economic inputoutput models forenvironmental Life-Cycle assessment. ACS Environmental Science and
Technology 4, 184A191A.Hes, D., 1998. The Olympic stadium analysed using the DPWS. Centre for Design at
RMIT: (August 26, 2010).Hes, D., 2001. ABS Offices, Belconnen ACT. Centre for Design at RMIT: < http://
buildlca.rmit.edu.au/menu9.html> (August 26, 2010).Hes, D., 2001. 60L Green Building. Centre for Design at RMIT: (August 26, 2010).International Energy Agency, 2005. IEA Annex 31. Energy related environmental
impacts of buildings: (January 23,2011).
Junnila, S., 2004. Life Cycle Assessment of environmentally significant aspects of anoffice building. Nordic Journal of Surveying and Real Estate Research 2 (SpecialSeries), 8197.
Junnila, S., 2004. The environmental impact of an office building throughout its lifecycle, Doctoral dissertation, Research report 2, Helsinki University ofTechnology Construction Economics and Management, Espoo, Finland.Extended overview: (January 23, 2011).
Kofoworola, O.F., Gheewala, S.H., 2008. Environmental Life Cycle Assessment of acommercial office building in Thailand. International Journal of Life CycleAssessment 13 (6), 498511.
Kohler, N., 2007. Recycling demolition arising at Cardiff city centre. Waste &Resources Action Programme, Project Code WAS006-002: (August 23, 2010).
Kohler, N., 2007. Recycling demolition arising at Gairbraid Avenue in Glasgow.Waste & Resources Action Programme, Project Code WAS006-002: (August 23, 2010).
Kohler, N., Davies, S., 2007. Recycling demolition arising at the Bryan Donkin site.Waste & Resources Action Programme, Project Code WAS006-002: (August 23, 2010).
Krogmann, U., Minderman, N., Senick, J., Andrews, C., 2009. Life-cycle assessment ofa green educational building: a case-study. Proceedings of the Life CycleAssessment IX Toward the global life cycle economy, 29 September-2 Octoberpaper 166. Boston, USA.
Lasvaux, S., Peuportier, B., Chevalier, J., 2009. Modeling the recycling processes inthe LCA of buildings. Proceedings of the 1st International Exergy, Life CycleAssessment and Sustainability Workshop and Symposium (ELCAS), NisyrosIsland, Greece, chapter V, article 12.
Leontief, W., 1970. Environmental repercussions and economic structure inputoutput approach. Review of Economics and Statistics 52 (3), 262271.
Mithraratne, Nalanie, Vale, Branda, 2004. Life cycle analysis model for New Zealandhouses. Building and Environment 39 (4), 483492.
Pascualino, J.C., Ortiz, O.O., Castells, F., 2008. Life Cycle Assessment as a tool formaterial selection and waste management within the building sector. In:Kenny, P., Brophy, V., Owen Lewis, J. (Eds.), PLEA Dublin 2008. Proceedings ofthe PLEA 200825th Conference on Passive and Low Energy Architecture, 2224October, paper 556. Dublin, Ireland.
Peuportier, B., 2001. Life Cycle Assessment applied to the comparative evaluation ofsingle family houses in the French context.Energy andBuildings33 (5),443450.
Peuportier, B., Putzeys, K., 2005. Inter-comparison and benchmarking of LCA-basedenvironmental assessment and design tools. Practical Recommendations forSustainable Construction (PRESCO), Work Package 2 Final Report, February2005: (August 30, 2010).
Pinto, A., 2008. Life cycle assessment applied to the environmental and energyanalysis of buildings. PhD Thesis in Mechanical Engineering, Instituto SuperiorTcnico, Technical University of Lisbon, Portugal (in Portuguese).
Schuer, C., Keoleian, G.A., Reppe, P., 2003. Life cycle energy and environmentalperformance of a new university building: modelling challenges and designimplications. Energy and Buildings 35 (10), 10491064.
Southworth, M.J., 2009. Building 802 Deconstruction project deconstructionresults report. Alameda County Waste Management Authority, Oakland, U.S.A.:(February 19, 2010).
Thormark, C., 2001. A low energy building in a life cycle its embodied energy, needfor operation and recycling potential. Building and Environment 37 (4), 429435.
Weil, M., Jeske, U., Schebek, Liselotte., 2006. Closed-loop recycling of constructionand demolition waste in Germany in view of stricter environmental thresholdvalues. Waste Management & Research 24 (3), 197206.
Xiaodong, L., Zhu, Y., Zhihui, Z., 2010. An LCA-based environmental impactassessment model for construction processes. Building and Environment 45
(3), 766775.
A. Coelho, J. de Brito / Waste Management 32 (2012) 532541 541
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