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Citation: Mayowa, B.; Chinda, T.
Environmental Assessment of
Demolition Tools Used in Townhouse
Demolition: System Dynamics
Modeling. Sustainability 2023,15,
14382. https://doi.org/10.3390/
su151914382
Academic Editor: Cinzia Buratti
Received: 4 September 2023
Revised: 22 September 2023
Accepted: 25 September 2023
Published: 29 September 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
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conditions of the Creative Commons
Attribution (CC BY) license (https://
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4.0/).
sustainability
Article
Environmental Assessment of Demolition Tools Used in
Townhouse Demolition: System Dynamics Modeling
Bamisaye Mayowa and Thanwadee Chinda *
School of Management Technology, Sirindhorn International Institute of Technology, Thammasat University,
Muang, Pathum Thani 12000, Thailand; d6322300069@g.siit.tu.ac.th
*Correspondence: thanwadee@siit.tu.ac.th
Abstract:
To accommodate population growth and migration to cities, many infrastructures have
been demolished to build new residential units. Demolition processes cause various environmental
problems globally and locally. The selection of methods used in demolition is crucial to reduce the
long-term environmental impact. This study considers various combination tools used in townhouse
demolition in Thailand, examines their environmental impacts, and suggests the combination of
the tools to be used in the long term. The system dynamics (SD) modeling approach is utilized
in this study to capture the changes in townhouse units, sizes, demolition tools, demolition time,
and the work rates of tools and their effects on the environment. This approach has the capability
to model complex relationships and examine long-term trends. Secondary data are employed to
identify variables necessary for SD model development, such as the different sizes of townhouses in
Thailand, the various types of demolition tools used in the construction industry, and environmental
impacts from building demolition. The simulation results revealed that Combination 4, i.e., the use
of demolition robots and hydraulic splitters, is the most effective combination to reduce the final
impact percentage in the long term. Compared with the other three combinations, it generates the
lowest CO
2eq
emissions, energy consumption, noise, dust, and heat. If demolition robots are not
yet available, Combination 1 (i.e., the use of excavators, jackhammers, and flame-cutters) offers the
lowest environmental impact in the long term. This study provides guidelines for decision-makers in
the construction industry to make sustainable choices of demolition tools and techniques used for
townhouse demolition to reduce long-term environmental impacts.
Keywords:
demolition tool; environmental assessment; system dynamics modeling; Thailand; townhouse
1. Introduction
The residential construction market remains Thailand’s largest segment of construction
projects, accounting for 35.4% of the industry’s total value in 2021 [
1
]. Almost 20% of the
nation’s housing supply is in the Bangkok Metropolitan Region (BMR) [
2
]. Bangkok
has different housing mixes, with a lower proportion of detached houses and a higher
proportion of townhouses. Townhouses are buildings containing three or more dwelling
units connected side by side in a row. These units typically have entrances and appear to be
one building or several distinct structures [
3
]. With a significant increase in the population
in Bangkok, the number of residential demands to accommodate Bangkok citizens has
increased. A high rate of urbanization leads to enormous pressure for efficient utilization
of the existing land. Many buildings are demolished before their expected lives to rebuild
new structures.
Demolition operation is dangerous, and a building survey must be performed before
the demolition so that it may not cause severe damage to the environment, public, and
adjacent properties. Various studies mention various demolition methods. For example,
The Constructor [
4
] categorizes demolition methods for buildings and structures into
non-explosive, i.e., sledgehammers, excavators, bulldozers, wrecking balls, and explosive
Sustainability 2023,15, 14382. https://doi.org/10.3390/su151914382 https://www.mdpi.com/journal/sustainability
Sustainability 2023,15, 14382 2 of 25
techniques. Jing et al. [
5
] discussed factors affecting the selection of concrete structure
demolition methods and concluded that traditional and eco-friendly demolition tools
should be used in concrete structure demolition work. Shweta and Khandvi [
6
] listed dif-
ferent applications of demolition tools, such as hammers, rammers, excavators, bulldozers,
wrecking balls, and explosives. Several demolition tools have been adopted in different
countries. For example, Singh et al. [
7
] highlighted demolition tools, such as hand-held
tools, rig-mounted breakers, and rig-mounted crushers in building demolition in India. In
Singapore, a top-down method is commonly used in demolition [
8
]. Machineries, such as
excavators and crushers, are lifted to the top of the building, and the demolition is carried
out progressively from top to bottom [
8
]. In Thailand, the demolition tools used in civil
demolition include jackhammers, excavators, hydraulic splitters, flame-cutters, wall and
saw cutters, and wrecking balls [
9
]. In Japan, the traditional methods of explosives and
iron balls are used in demolition [10].
The selection of demolition tools used in the demolition affects the environment
differently. For example, excavators may generate noise, dust, and vibration in the local
area and consume fuel that releases CO
2
into the atmosphere, causing greenhouse gas
(GHG) emissions. Jackhammers, when in use, generate noise, vibration, and dust, while
saw cutters and flame cutters create noise and heat, respectively [
10
]. With more buildings
to be demolished in Thailand, selecting demolition tools is crucial in terms of economic and
environmental perspectives. For example, using excavators and jackhammers in demolition
may cause higher dust levels but lower energy consumption than using excavators and
hydraulic splitters [
10
]. Many studies have utilized several methods in selecting demolition
tools, for example, Abdullah and Anumba, [
11
] used the analytic hierarchy process (AHP)
as one of the multicriteria decision-making approaches to develop a tool for demolition
technique selection and concluded that by using developed tools, demolition engineers
can make more informed decisions on demolition techniques, based on a sound technical
framework. Anumba et al. [
12
] used an integrated system for demolition technique selection
and concluded that the prototype system developed provides users with a clear and
structured framework that could improve the decision–making process. Oryza et al. [
13
]
utilized the selecting model of building demolition method based on an expert system
and concluded that the model can make decisions on the selection of demolition methods
with an accuracy of judgment. However, unstructured intuition by demolition engineers
based on skill, experience, judgment, or knowledge may sometimes lead to error and
inconsistencies, and the AHP utilized in selecting demolition tools are linear dependencies
between items of different decision-making levels and not suitable for complex problems
which are characterized by dependencies, interactions, and feedback and especially by the
dynamic nature of the decision taken. To tackle these, the inadequacies system dynamics
(SD) modeling approach is utilized in this study to capture relationships among crucial
factors affecting the demolition process and environmental impacts, such as the number and
sizes of townhouses to be demolished, the demolition tools used in the demolition process
and environmental impacts from the demolition process. The study results are expected to
provide a better understanding of the demolition process and guide the selection of tools to
reduce the environmental impacts on local and global scales in the long term.
2. Literature Review
2.1. Townhouse Demolition in Bangkok
According to Macrotrends [
14
], the population in Bangkok in 2023 is
11,070,000 persons
,
and given the ongoing migration into the city, the population could potentially surge to
12,680,000 persons by 2030. This population growth has exerted significant pressure on the
demand for housing in the city, prompting entrepreneurs to invest in construction projects to
provide different types of housing, including detached houses, townhouses, and condomini-
ums. In Bangkok, townhouses contribute to about half of all housing units as they offer more
space than condominiums and lower prices than detached houses [15] (See Figure 1).
Sustainability 2023,15, 14382 3 of 25
Sustainability2023,15,xFORPEERREVIEW3of25
projectstoprovidedifferenttypesofhousing,includingdetachedhouses,townhouses,
andcondominiums.InBangkok,townhousescontributetoabouthalfofallhousingunits
astheyoffermorespacethancondominiumsandlowerpricesthandetachedhouses[15]
(SeeFigure1).
Figure1.Bangkokhousingunits[15,16].
InBangkok,townhousesaredividedintosmall,medium,andlargesizes[1].Small-
sizedtownhouseshaveincreasedsignificantlyinrecentyears,risingfrom20%ofthetotal
townhouseunitsin2014to60%in2022[16].Anincreaseinpopulationanddevelopment
inBangkokhasresultedinthereconstructionanddemolitionofbuildings.Poombeteet
al.[17]statedthatdemolitionunitsinThailandmakeupabout10%ofthenewbuilding
permitseachyear.
2.2.DemolitionToolsUsedinDemolitioninThailand
InThailand,traditionalmethodsofdemolition,whichinvolveexcavators,jackham-
mers,sledgehammers,wreckingballs,hydraulicspliers,flamecuers,andsawcuers,
areusedinbuildingdemolition[9].Thesetoolshaveawiderangeofapplicationsinbuild-
ingdemolition.Forexample,excavatorsareequippedwithdifferenttools,suchaspulver-
izes,shears,breakers,andselectorgrabaachmentstobreakoutsteelandconcreteand
striptheupperfloorofthebuilding[18].Jackhammersaremadeofalonghandle,arma-
ture,cushion,andgearthatperformconcretedemolitionanddrillingoperations[19].
Flamecuerscancutthroughamaximumdepthof60incheswithorwithoutareinforcing
rod[20].
AccordingtoJingetal.[5],eco-friendlygreendemolitionmethodswithnoormini-
malenvironmentalimpactshouldbeadoptedinThaibuildingdemolitiontoreducethe
environmentalimpactsinthelongterm.Itisanexcellentsolutiontominimizevarious
environmentalissuesindemolition,suchasnoise,vibration,anddust[11].Althoughitis
notyetavailableinThailand,itshouldbeconsideredasatechniqueusedinthefutureto
reducetheimpactsofdemolitionontheenvironment.
Thisstudyconsidersfivedemolitiontoolsusedintownhousedemolition:excavators,
hydraulicspliers,jackhammers,flamecuers,anddemolitionrobots,astheywerere-
trievedfromtheliteratureandwereconfirmedbyexpertsininterviews.
2.3.EnvironmentalImpactsofDemolitionToolsUsedinDemolition
Indemolition,therightchoiceoftoolsisessentialasdemolitionseverelyimpactsthe
environment,safety,andtherecyclingofmaterialsandcomponents.Highprecautions
andrequirementsshouldbeemployedandmeasuredtomitigatetheenvironmental
Figure 1. Bangkok housing units [15,16].
In Bangkok, townhouses are divided into small, medium, and large sizes [
1
]. Small-
sized townhouses have increased significantly in recent years, rising from 20% of the total
townhouse units in 2014 to 60% in 2022 [
16
]. An increase in population and development
in Bangkok has resulted in the reconstruction and demolition of buildings. Poombete
et al. [
17
] stated that demolition units in Thailand make up about 10% of the new building
permits each year.
2.2. Demolition Tools Used in Demolition in Thailand
In Thailand, traditional methods of demolition, which involve excavators, jackham-
mers, sledgehammers, wrecking balls, hydraulic splitters, flame cutters, and saw cutters,
are used in building demolition [
9
]. These tools have a wide range of applications in
building demolition. For example, excavators are equipped with different tools, such as
pulverizes, shears, breakers, and selector grab attachments to break out steel and concrete
and strip the upper floor of the building [
18
]. Jackhammers are made of a long handle,
armature, cushion, and gear that perform concrete demolition and drilling operations [
19
].
Flame cutters can cut through a maximum depth of 60 inches with or without a reinforcing
rod [20].
According to Jing et al. [
5
], eco-friendly green demolition methods with no or mini-
mal environmental impact should be adopted in Thai building demolition to reduce the
environmental impacts in the long term. It is an excellent solution to minimize various
environmental issues in demolition, such as noise, vibration, and dust [11]. Although it is
not yet available in Thailand, it should be considered as a technique used in the future to
reduce the impacts of demolition on the environment.
This study considers five demolition tools used in townhouse demolition: excava-
tors, hydraulic splitters, jackhammers, flame cutters, and demolition robots, as they were
retrieved from the literature and were confirmed by experts in interviews.
2.3. Environmental Impacts of Demolition Tools Used in Demolition
In demolition, the right choice of tools is essential as demolition severely impacts the
environment, safety, and the recycling of materials and components. High precautions and
requirements should be employed and measured to mitigate the environmental effects of
demolition operations. Environmental issues occur at different levels, including local and
global levels. Hemlata et al. [
21
] listed local environmental issues as desertification, water
scarcity, water contamination, soil contamination, noise pollution, heat, and dust. Global
environmental issues, on the other hand, include global warming, ocean acidification,
acid rain, and ozone depletion [
21
,
22
]. Different combinations of demolition tools result
in various environmental impacts. For example, excavators and jackhammers generate
Sustainability 2023,15, 14382 4 of 25
noise and dust, which are considered local environmental impacts, and CO
2
emissions
and energy consumption, which are regarded as global environmental impacts [
10
]. Flame
cutters generate heat (i.e., local impact), energy consumption, and CO
2
emissions (i.e.,
global impacts) [
20
]. Hydraulic splitters and demolition robots consume energy and release
CO2into the atmosphere, causing global environmental impacts [22].
Several methods may be used to examine the environmental impacts in the construc-
tion industry. For example, Chooi et al. [
23
] utilized life cycle assessment (LCA) to assess
the environmental impact associated with all stages of construction and demolition waste
(CDW) from waste production to the end of life of waste material.
Fantozzi et al. [24]
uti-
lized a life cycle cost analysis to identify the cost-optimal level among different design
solutions to improve the energy performance of existing buildings in Italy.
Abraham et al. [25]
conducted an experimental study on concrete blocks using CDW to enhance waste recycling.
Coelho and Brito [
26
] used the environmental analysis method to evaluate the CDW recycling
plant in Portugal. Jones and Smith [
27
] utilized system dynamics to model the selection
of demolition methods. The model identifies a few factors that influence the selection of
demolition methods, including the size and type of structure to be demolished, the cost of
demolition, the environmental impact of demolition, and the safety of the demolition worker.
Brown and Smith [28]
developed decision support tools for the selection of demolition meth-
ods using system dynamics. The tools consider many factors such as the cost of demolition,
and the environmental impact of demolition. Jones and Smith [
29
] assessed the environmental
impact of different demolition methods and concluded that some demolition methods such
as controlled demolition have a lower environmental impact than other methods, such as
wrecking ball demolition. Brown and Smith [
30
] utilized SD modeling to examine the safety
of demolition workers; the study found that demolition is a dangerous occupation and that
many factors contribute to harm and death among the demolition workers.
2.4. Importance Weights of the Environmental Impacts
Environmental impacts caused by demolition activities using different demolition tools
vary. To determine the importance of each impact, academic journals related to the global
and local impacts of the demolition process were retrieved from a well-known database,
i.e., the Scopus database, on 23 April 2023 to be used to represent the importance of each
impact [
31
,
32
]. The ‘title/abstract/keyword’ was used to comprehensively search through
the Scopus search engine to capture the impact associated with the building demolition
process over 15 years, from 2009 to 2023. The search excludes irrelevant subject areas and
is limited to English journal articles. The final number of articles related to this study is
90 articles. They are further input with environmental impacts found in the literature.
Table 1reveals five impacts, namely CO
2
equivalent emissions, energy consumption, noise,
dust, and heat, in the demolition-related studies. These five impacts are weighted using
the lowest-frequency impacts, which are heat and dust, as the base impact with a weight
of 1 (see Table 1). The CO
2
equivalent emissions are the most important environmental
impact in building demolition processes, with an importance weight of 21.7. It affects
the environment globally and is confirmed by several studies. For example, Ali et al. [
33
]
mentioned that CO
2
is one of the dominant compound elements of greenhouse gases and
the principal causal factor of global warming. It accounts for overall global warming effects
that are a main driver of climate change.
Table 1.
Environmental impacts of demolition processes and their importance weights based on the
Scopus database.
Environmental Impact Frequency Importance Weight
CO2equivalent emission 65 21.7
Primary energy consumption 19 6.3
Noise 4 1.3
Dust 3 1
Heat 3 1
Sustainability 2023,15, 14382 5 of 25
Table 1. Cont.
Environmental Impact Frequency Importance Weight
Soil contamination 0 0
Vibration 0 0
Water contamination 0 0
Ocean acidification 0 0
Drought 0 0
Acid rain 0 0
Desertification 0 0
Total 94 31.3
The five key impacts and their importance weights were input into the SD model to
calculate the total environmental impact of different combinations of demolition tools used
in the demolition process.
3. Research Methodology
3.1. System Dynamics Modeling Approach
In this study, an SD modeling approach was utilized to examine the environmental
impacts of different combinations of demolition tools used in the demolition process in
the long term. It is used to foresee possible long-term effects of policies that cannot be
easily understood due to the complex nature of the system [
34
]. It allows the relationships
among important variables affecting a problem to be examined and provides a better
understanding and possible solutions. The decisions of tool combinations used in the
building and their expected impacts are complex systems and require joint efforts from
various parties, such as the environmental protection department, demolition engineers,
and the government.
The SD modeling approach has been utilized in several construction research stud-
ies, including waste management, environmental impact assessment, and construction
performance. For example, Doan and Chinda [
35
] utilized an SD modeling technique to in-
vestigate the feasibility of a CDW recycling program in Bangkok, Thailand.
Ding et al. [36]
developed an SD model to examine the environmental performance of construction waste
reduction management in China. Liu et al. [
37
] evaluated the environmental impact of
various CDW management methods, namely illegal dumping, landfilling, and waste recy-
cling and reuse in Guangzhou, China. It was found that socio-economic losses increased
by increasing land loss and global warming potential, both of which are affected by illegal
waste disposal and landfill disposal.
3.2. Data Collection Method
3.2.1. Secondary Data Collection
The secondary data used in the SD model development were collected from various
sources, such as journals, statistical data from the government and related authorities,
company reports, and websites [
1
]. For example, the typical townhouses in Bangkok,
Thailand, have three sizes: small, medium, and large [
1
]. The power sound levels of
excavators and jackhammers are 112 and 113 decibels, respectively [
38
]. The dust levels of
the manual (i.e., jackhammers) and mechanical (i.e., excavators) tools are 3.4 and 1.4 mg/m
3
,
respectively [
39
]. A summary of the secondary data used in the SD model development is
in Table 2.
Sustainability 2023,15, 14382 6 of 25
Table 2. Summary of secondary data used in the SD model development.
Data Details Description Reference
Housing unit
•Housing unit in
Bangkok
•Average annual growth: 2.56%
•Initial unit: 2,400,540
[2,3,15–17]
•Townhouse unit
•Percentage of townhouse units in Bangkok: 51%
of total housing units
•Townhouse size
#Small: 60–80 m2
#Medium: 81–112 m2
#Large: >112 m2
•Percentage of townhouse sizes:
#Small: 38% of total townhouse units
#Medium: 20% of total townhouse units
#Large: 42% of total townhouse units
•Changes in townhouse sizes:
#Small: 6.4% increase annually
#Medium: 5.6% increase annually
#Large: 5.4% decrease annually year
•
Townhouse demolition: 10% of the new structure
permits annually
Demolition tools and their
environmental impacts
•Excavator
•CO2eq emissions: 2.025 kgCO2eq /kWh with a
power rating of 210 kW
•Primary energy consumption: 0.086 kgoe/kWh
with a power rating of 210 kW
•Noise: 112 decibels
•Dust: 1.4 mg/m3
[20,22,38–43]
•Jackhammer
•CO2eq emissions: 0.424 kgCO2eq /kWh with a
power rating of 2.2 kW
•Primary energy consumption: 1.952 kgoe/kWh
with a power rating of 2.2 kW
•Noise: 113 decibels
•Dust: 3.4 mg/m3
•Flame cutter
•CO2eq emissions: 0.424 kgCO2eq /kWh with a
power rating of 1.5 kW
•Primary energy consumption: 1.952 kgoe/kWh
with a power rating of 1.5 kW
•Heat: 850 kJ
•Hydraulic splitter
•CO2eq emissions: 0.424 kgCO2eq /kWh with a
power rating of 11.2 kW
•Primary energy consumption: 1.952 kgoe/kWh
with a power rating of 11.2 kW
•Demolition robot
•CO2eq emissions: 0.424 kgCO2eq /kWh with a
power rating of 27 kW
•Primary energy consumption: 1.952 kgoe/kWh
with a power rating of 27 kW
Work time •Working hours •8 h/day
Sustainability 2023,15, 14382 7 of 25
3.2.2. Primary Data Collection
Primary data were collected through interviews with experts in the construction in-
dustry. Dworkin [
44
] suggested that at least five interviewees be involved in the interviews.
In this study, eight experts provided information and data input for the SD model develop-
ment. They are involved in structural demolition projects, such as buildings, roads, bridges,
basements, and retaining walls, with more than ten years of experience (see Table 3). They
provide the necessary information, such as the demolition tools used in building demolition
in Thailand, the work rates of demolition tools for different levels of townhouse demolition,
and the use of demolition robots in Thailand.
Based on Table 3, three combinations of demolition tools were decided upon with
an average work rate for each tool. The experts also agree on using demolition robots to
replace excavators in the future to reduce the environmental impacts effectively. This results
in an additional combination (i.e., Combination 4) of this study’s demolition robot and
hydraulic splitter. Details of each combination are summarized based on the interviews;
see Table 4.
Sustainability 2023,15, 14382 8 of 25
Table 3. Primary data used in the SD model development.
Information Interviewee
#1 #2 #3 #4 #5 #6 #7 #8
Position Supervisor Engineer Engineer Supervisor Supervisor Engineer Executive Engineer
Work experience 15 years 12 years 10 years 15 years 13 years 13 years 15 years 10 years
Involvement in
building
demolition
Yes Yes Yes Yes Yes Yes Yes Yes
Demolition work Buildings and
bridges
Buildings and
retaining walls Buildings Buildings Buildings and
bridges Buildings Buildings Buildings
Combination of
demolition tools
Excavators,
jackhammers, and
flame cutters
Excavators,
jackhammers, and
flame cutters
Excavators,
jackhammers, and
flame cutters
Excavators,
jackhammers, and
hydraulic splitters
Excavators,
jackhammers, and
hydraulic splitters
Excavators,
jackhammers, and
hydraulic splitters
Excavators,
and
hydraulic
splitters
Excavators,
and
hydraulic
splitters
Demolition time
for different
townhouse sizes
Small: 8 days
Medium:
12 days
Large: 16 days
Small: 7 days
Medium:
10 days
Large: 15 days
Small: 8 days
Medium:
12 days
Large: 16 days
Small: 7 days
Medium:
13 days
Large: 15 days
Small: 8 days
Medium:
11 days
Large: 16 days
Small: 8 days
Medium:
12 days
Large: 16 days
Small: 6 days
Medium:
12 days
Large: 14 days
Small: 9 days
Medium:
13 days
Large: 16 days
Knowledge of
demolition robots Yes Yes Yes Yes Yes Yes Yes Yes
Sustainability 2023,15, 14382 9 of 25
Table 4. Four combinations of demolition tools acquired from the interviews.
Detail Combination
1 2 3 4
Demolition tools
•Excavator
•Jackhammer
•Flame cutter
•Excavator
•Jackhammer
•Hydraulic splitter
•Excavator
•Hydraulic splitter
•Demolition robot
•Hydraulic splitter
Number of
tools used for
demolition
•Small-sized townhouse
#Excavator: 1
#Jackhammer: 2
#Flame cutter: 2
•Small-sized townhouse
#Excavator: 1
#Jackhammer: 2
#Hydraulic splitter: 2
•Small-sized townhouse
#Excavator: 1
#Hydraulic splitter: 3
•Small-sized townhouse
#Demolition robot: 1
#Hydraulic splitter: 3
•Medium-sized townhouse
#Excavator: 1
#Jackhammer: 4
#Flame cutter: 2
•Medium-sized townhouse
#Excavator: 1
#Jackhammer: 4
#Hydraulic splitter: 2
•Medium-sized townhouse
#Excavator: 1
#Hydraulic splitter: 4
•Medium-sized townhouse
#Demolition robot: 1
#Hydraulic splitter: 4
•Large-sized townhouse
#Excavator: 1
#Jackhammer: 6
#Flame cutter: 4
•Large-sized townhouse
#Excavator: 1
#Jackhammer: 6
#Hydraulic splitter: 3
•Large-sized townhouse
#Excavator: 1
#Hydraulic splitter: 6
•Large-sized townhouse
#Demolition robot: 1
#Hydraulic splitter: 6
Work rate
based on total work time
•Excavator: 50%
•Jackhammer: 40%
•Flame cutter: 10%
•Excavator: 60%
•Jackhammer: 10%
•Hydraulic splitter: 30%
•Excavator: 70%
•Hydraulic splitter: 30%
•Demolition robot: 70%
•Hydraulic splitter: 30%
Sustainability 2023,15, 14382 10 of 25
4. Development of an SD Model of the Environmental Impact of Demolition Tools
Used in Townhouse Demolition
The SD model of the environmental impact of demolition tools used in townhouse
demolition in Thailand was developed based on secondary and primary data. It consists of
seven sub-models, namely (1) townhouse units demolished, (2) CO
2
equivalent emission
percentage, (3) primary energy consumption percentage, (4) noise percentage, (5) dust
percentage, (6) heat percentage, and (7) final impact percentage sub-model.
4.1. Townhouse Demolition Sub-Model
Bangkok’s housing units were 2,400,540 in 2013, with an average increasing rate of
2.56% [
2
]. Among those, 51% are townhouses [
15
]. Poombete et al. [
17
] mentioned that the
number of townhouses to be demolished is about 10% of new construction permits per
year. This leads to the number of townhouses being demolished (THD) (see the SD model
equations in Appendix A). Klinmalai et al. [
3
] stated that townhouses are divided into three
sizes: small, medium, and large. On average, the number of small-sized townhouses tends
to increase by 6.4% per year, while large-sized townhouses decrease by 8.5% per year [
16
].
This leads to the number of small-, medium-, and large-sized townhouses to be demolished
(i.e., STHD, MTHD, and LTHD, respectively). Different numbers and sizes of townhouses
and tool combinations used in the demolition affect the environment differently. For
example, large-sized townhouses require more extensive work time for excavators than
medium- and small-sized townhouses. This may result in more dust, noise, and primary
energy consumption from the excavators.
4.2. CO2Equivalent Emission Percentage Sub-Model
The CO
2
equivalent emissions of primary electricity generation were calculated using
a conversion factor of 0.495 kgCO
2eq
/kWh for demolition equipment using electricity
and 2.025 kgCO
2eq
/kWh for diesel-powered excavators [
40
]. The CO
2eq
emissions of
each tool were estimated by multiplying the primary energy consumption, the conversion
factors, the number of tools used, the work rates of the tools, and the time used for
demolition. Equations (1) – (3) show examples of CO
2eq
emission calculation (in kgCO
2eq
)
in Combination 1 using diesel excavators (CO
2eq
EX1), electric jackhammers (CO
2eq
JH1),
and flame cutters (CO2eqFC1) (see in Abbreviations).
CO2eqEX1 =2.025 ×PEX1 ×0.5[(STHD ×64)+(MTHD ×96)+(LTHD ×128)] (1)
CO2eqJH1 =0.495 ×PJH1 ×[(STHD ×2×64)+(MTHD ×4×96 )+(LTHD ×6×128 )] (2)
CO2eqFC1 =0.495 ×PFC1 ×[(STHD ×2×64)+(MTHD ×2×96)+(LTHD ×4×128)] (3)
The calculated CO
2eq
emissions of excavators, jackhammers, and flame cutters in
Combination 1 were summed to achieve the total CO
2eq
emissions of this combination. The
CO
2eq
emissions of the four combinations were compared, and the highest calculated CO
2eq
emissions were considered to have a 100% CO
2eq
emission percentage (i.e., the worst impact
percentage among the four combinations). The combinations with the lower CO
2eq
emis-
sions are adjusted to achieve the CO
2eq
emission percentages (see
Equations (4) and (5)
).
MAXTCO2eq =MAX(TCO2eq1, TCO2eq2, TCO2eq3, TCO2eq4)(4)
TCO2eq1N =TCO2eq1/MAXTC02eq ×100 (5)
4.3. Primary Energy Consumption Percentage Sub-Model
The primary energy consumption for the demolition tools used in Combination 1
(i.e., excavators, jackhammers, and flame cutters) was calculated by multiplying the power
Sustainability 2023,15, 14382 11 of 25
rating of the demolition tools, the energy conversion coefficient, the work rates of the
demolition tools, the operating hours of the tools, and the number of tools used. For
example, diesel-powered excavators have a power rating of 210 kW, an energy conversion of
0.086 kgoe/kWh, and a work rate of 50% of total work time in Combination 1. Jackhammers
have a power rating of 2.2 kW, an energy conversion of 1.952 kgoe/kWh, and a work rate of
40% of total work time. Flame cutters have a power rating of 1.5 kW, an energy conversion
of 1.952 kgoe/kWh, and a work rate of 10% of total work time. Small-, medium-, and large-
sized townhouses require one excavator each, two, four, and six jackhammers, respectively,
and two, two, and four flame cutters for demolition, respectively. With the total work times
of 64, 96, and 128 h for small-, medium-, and large-sized townhouses, respectively, the
primary energy consumptions are calculated; see Equations (6)–(8). The calculated primary
energy consumptions of excavators, jackhammers, and flame cutters in Combination 1
were summed to achieve the total primary energy consumption and adjusted to achieve
the primary energy consumption percentages of Combination 1.
PEXI =210 ×0.086 ×0.5[(STHD ×64)+(MTHD ×96)+(LTHD ×128)] (6)
PJH1 =2.2 ×1.952 ×0.4[(STHD ×2×64)+(MTHD ×4×96)+(LTHD ×6×128)] (7)
PFC1 =1.5 ×1.952 ×0.1[(STHD ×2×64)+(MTHD ×2×96)+(LTHD ×4×128)] (8)
4.4. Noise Percentage Sub-Model
Noise generated during the demolition process varies, depending on the nature of the
equipment used [
38
]. The noise percentage of each demolition tool in each combination
is calculated based on the noise levels of demolition tools, the sizes of the townhouses
to be demolished, the work rates of the demolition tools, the number of demolition tools
used, and working hours (see Tables 2–4). Equations (9) and (10), for example, show
the calculated noise of Combination 1 (i.e., noise from excavators and jackhammers, as
flame cutters generate no noise). The calculated noises of excavators and jackhammers in
Combination 1 were summed to achieve the total noise and adjusted to achieve the noise
percentages of Combination 1. It is noted that only excavators and jackhammers generate
noise during demolition.
NEX1 =112 ×0.5[(STHD ×64)+(MTHD ×96)+(LTHD ×128)] (9)
NJH1 =113 ×0.4[(STHD ×2×64)+(MTHD ×4×96)+(LTHD ×6×128) ) (10)
4.5. Dust Percentage Sub-Model
The excavators and jackhammers in Combination 1 generate dust, as in
Equations (11) and (12)
. The calculated dust of the excavators and jackhammers in Combi-
nation 1 was summed to achieve the total dust and adjusted to achieve the dust percentages
of Combination 1.
EX1 =1.4 ×0.5[(STHD ×64)+(MTHD ×128)+(LTHD ×128)] (11)
DJH1 =3.4 ×0.4 [(STHD ×2×64)+(MTHD ×4×96)+(LTHD ×6×128)] (12)
4.6. Heat Percentage Sub-Model
The flame cutters in Combination 1 generate heat of 850 kJ, as in Equation (13). The
heat generated is calculated from the number and sizes of the townhouses to be demolished,
Sustainability 2023,15, 14382 12 of 25
work rates, and the number of demolition tools in each combination. It is noted that only
the flame cutters in Combination 1 generate heat.
HFC1 =850 ×0.1[(STHD ×2×64)+(MTHD ×2×96)+(LTHD ×4×128)] (13)
4.7. Final Impact Percentage Sub-Model
The five calculated environmental impact percentages were weighted with their impor-
tance weights achieved in Table 1. For example, the estimated CO
2eq
emission percentage of
Combination 1 was multiplied by 21.7 (i.e., the importance weight of the CO
2eq
emissions,
see Table 1) to achieve the weighted percentage. In each combination, the weighted percent-
ages of the five environmental impacts (i.e., CO
2eq
emissions, primary energy consumption,
noise, dust, and heat) were summed and divided by the total importance weight of 31.3
(see Table 1) to achieve the final impact percentage. Equation (14) shows the final impact
percentage of Combination 1.
FIC1 =((TCO2eq1N ×21.7)+(TP1N ×6.3)+(TN1N ×1.33)+(TD1N ×1)+(TH1N ×1))/31.3 (14)
5. Results
5.1. Simulation Results
The SD model of demolition tools used in townhouse demolition was simulated for
20 years to examine the environmental impact of the different tool combinations used
in townhouse demolition in the long term. However, Combination 4, which includes
demolition robots and hydraulic splitters, was simulated after ten years to initiate the
possibility of this new demolition method in actual practice. Table 5shows the number of
townhouses to be demolished in the next 20 years. More small-sized townhouses are to be
built and demolished to accommodate the growth and migration of the population into
the city. This is consistent with Risland Thailand [
16
] in that consumers tend to purchase
small-sized townhouses in Bangkok due to the rise of land and townhouse prices.
Table 5. Simulation results of townhouses to be demolished.
Year STHD (Units) MTHD (Units) LTHD (Units) THD (Units)
2023 2159 993 931 4083
2024 2295 1008 909 4212
2025 2440 1018 887 4345
2026 2594 1023 865 4482
2027 2757 1022 844 4623
2028 2861 1083 824 4768
2029 2951 1163 804 4918
2030 3044 1245 784 5073
2031 3140 1328 765 5233
2032 3239 1412 747 5398
2033 3341 1498 729 5568
2034 3446 1586 711 5744
2035 3554 1676 694 5924
2036 3667 1767 677 6111
2037 3782 1861 661 6304
2038 3901 1951 650 6502
2039 4024 2012 671 6707
2040 4151 2075 692 6918
2041 4282 2141 714 7136
2042 4417 2771 173 7361
Figures 2and 3show that Combination 3 has the highest CO
2eq
emission and primary
energy consumption percentages. This is because excavators are one of the most energy-
intensive tools, and long work times result in increased energy consumption and CO
2
emissions [45].
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2039402420126716707
2040415120756926918
2041428221417147136
2042441727711737361
Figures2and3showthatCombination3hasthehighestCO2eqemissionandprimary
energyconsumptionpercentages.Thisisbecauseexcavatorsareoneofthemostenergy-
intensivetools,andlongworktimesresultinincreasedenergyconsumptionandCO2
emissions[45].
Combination1generatesthehighestnoiseanddustlevels,thusreceivingthehighest
noiseanddustpercentagesof100%;seeFigures4and5.Thisisbecausejackhammersare
oneofthedemolitiontoolsthatgeneratenoiseanddustduringdemolitionprocesses[38].
Incontrast,Combination3generatestheleastnoisepercentagecomparedwiththeother
threecombinations,i.e.,Combinations1–3.Combination4(i.e.,greendemolition)isrec-
ommendedinthelongterm,asitgeneratesnonoise.Combination1istheonlycombina-
tionthatgeneratesheatfromtheflamecuers(seeFigure6).Itresultsina100%heat
percentage.
Figure2.GraphicalresultsofCO2eqemissionpercentages.
0
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CO2eqemissionpercentage
Time(Year)
Combination1Combination2
Combination3Combination4
Figure 2. Graphical results of CO2eq emission percentages.
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Figure3.Graphicalresultsofprimaryenergyconsumptionpercentages.
Figure4.Graphicalresultsofnoisepercentages.
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Primaryenergyconsumption
percentage
Time(Year)
Combination1 Combination2
Combination3 Combination4
0
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100
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Noisepercentage
Time(Year)
Combination1Combination2
Combination3Combination4
Figure 3. Graphical results of primary energy consumption percentages.
Combination 1 generates the highest noise and dust levels, thus receiving the highest
noise and dust percentages of 100%; see Figures 4and 5. This is because jackhammers are
one of the demolition tools that generate noise and dust during demolition processes [38].
In contrast, Combination 3 generates the least noise percentage compared with the other
three combinations, i.e., Combinations 1–3. Combination 4 (i.e., green demolition) is recom-
Sustainability 2023,15, 14382 14 of 25
mended in the long term, as it generates no noise. Combination 1 is the only combination
that generates heat from the flame cutters (see Figure 6). It results in a 100% heat percentage.
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Figure3.Graphicalresultsofprimaryenergyconsumptionpercentages.
Figure4.Graphicalresultsofnoisepercentages.
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Primaryenergyconsumption
percentage
Time(Year)
Combination1 Combination2
Combination3 Combination4
0
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100
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Noisepercentage
Time(Year)
Combination1Combination2
Combination3Combination4
Figure 4. Graphical results of noise percentages.
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Figure5.Graphicalresultsofdustpercentages.
Figure6.Graphicalresultsofheatpercentages.
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Dustpercentage
Time(Year)
Combination1 Combination2
Combination3 Combination4
0
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Heatpercentage
Time(Year)
Combination1Combination2
Combination3Combination4
Figure 5. Graphical results of dust percentages.
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Figure5.Graphicalresultsofdustpercentages.
Figure6.Graphicalresultsofheatpercentages.
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Dustpercentage
Time(Year)
Combination1 Combination2
Combination3 Combination4
0
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Heatpercentage
Time(Year)
Combination1Combination2
Combination3Combination4
Figure 6. Graphical results of heat percentages.
The final impact percentages of the four combinations were achieved when the impor-
tance weights were considered. The results show that Combination 4, using demolition
robots, generates the lowest final impact of lower than 20%, mainly from primary energy
consumption and CO
2eq
emissions. The use of demolition robots proves to be the best
demolition method to reduce the environmental impact in the long term as it generates
almost four times less impact than the other three methods (see Figure 7). As CO
2
emissions
and energy depletion are global environmental concerns [
21
], operations that reduce these
impacts should be highly recommended.
Sustainability2023,15,xFORPEERREVIEW16of25
Thefinalimpactpercentagesofthefourcombinationswereachievedwhentheim-
portanceweightswereconsidered.TheresultsshowthatCombination4,usingdemoli-
tionrobots,generatesthelowestfinalimpactoflowerthan20%,mainlyfromprimary
energyconsumptionandCO2eqemissions.Theuseofdemolitionrobotsprovestobethe
bestdemolitionmethodtoreducetheenvironmentalimpactinthelongtermasitgener-
atesalmostfourtimeslessimpactthantheotherthreemethods(seeFigure7).AsCO2
emissionsandenergydepletionareglobalenvironmentalconcerns[21],operationsthat
reducetheseimpactsshouldbehighlyrecommended.
Combination3,incontrast,generatesthehighestfinalimpactpercentage,followed
byCombinations2and1,respectively.Withnodemolitionrobotsavailable,Combination
1offersthecombinationoftoolswiththelowestenvironmentalimpactinthelongterm.
Thismaybebecausethiscombinationutilizestheexcavatorswiththelowestworkrate,
resultinginlowCO2eqemissionsandprimaryenergyconsumption,whicharethetwo
mostsignificantimpactsinthedemolitionprocess.Combination2mayalsobeconsidered
fortownhousedemolitioninThailandintheearlyyearsasitgeneratesasimilarenviron-
mentalimpactasthatinCombination1.However,withmoresmall-sizedtownhousesto
bedemolished,thiscombinationhasahigherimpactinlateryears.
Figure7.Graphicalresultsofthefinalimpactpercentages.
5.2.ModelValidationandSensitivityAnalysis
ThedevelopedSDmodelofdemolitiontoolsusedintownhousedemolitioninThai-
landmustbevalidatedtoconfirmitsapplicationsinrealpracticesandascertainifashift
inmodelparameterscausesthemodeltofailthebehaviortestthatwaspreviouslypassed
[46].Sensitivityanalysisisastandardvalidationtesttoconfirmthemodel’sbehaviorand
buildconfidenceintheSDmodel[47].Inthisstudy,theexpertsprovidedvariousdemo-
litionperiodsforsmall-,medium-,andlarge-sizedtownhousesfrom6–9,10–13,and14–
16days,respectively(seeTab l e4).Thesensitivityanalysiswasthenperformedbyvarying
thedemolitiondaysforeachtownhousesize.Thesimulationresults,(Figures8–11),con-
firmthevalidationofthedevelopedSDmodelasonlymagnitudesoftheresultschange
andthemodel’sbehaviorsremainthesame.
0
20
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60
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100
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Finalimpactpercentage
Time(Year)
Combination1 Combination2
Combination3 Combination4
Figure 7. Graphical results of the final impact percentages.
Sustainability 2023,15, 14382 16 of 25
Combination 3, in contrast, generates the highest final impact percentage, followed
by Combinations 2 and 1, respectively. With no demolition robots available, Combination
1 offers the combination of tools with the lowest environmental impact in the long term.
This may be because this combination utilizes the excavators with the lowest work rate,
resulting in low CO
2eq
emissions and primary energy consumption, which are the two most
significant impacts in the demolition process. Combination 2 may also be considered for
townhouse demolition in Thailand in the early years as it generates a similar environmental
impact as that in Combination 1. However, with more small-sized townhouses to be
demolished, this combination has a higher impact in later years.
5.2. Model Validation and Sensitivity Analysis
The developed SD model of demolition tools used in townhouse demolition in Thai-
land must be validated to confirm its applications in real practices and ascertain if a shift in
model parameters causes the model to fail the behavior test that was previously passed [
46
].
Sensitivity analysis is a standard validation test to confirm the model’s behavior and build
confidence in the SD model [
47
]. In this study, the experts provided various demolition
periods for small-, medium-, and large-sized townhouses from 6–9, 10–13, and 14–16 days,
respectively (see Table 4). The sensitivity analysis was then performed by varying the
demolition days for each townhouse size. The simulation results, (Figures 8–11), confirm
the validation of the developed SD model as only magnitudes of the results change and the
model’s behaviors remain the same.
Sustainability2023,15,xFORPEERREVIEW17of25
Figure8.FinalimpactpercentagesofCombination1whenthedemolitionperiodischanged.
Figure9.FinalimpactpercentagesofCombination2whenthedemolitionperiodischanged.
70
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
70
80
90
100
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
Figure 8. Final impact percentages of Combination 1 when the demolition period is changed.
Sustainability 2023,15, 14382 17 of 25
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Figure8.FinalimpactpercentagesofCombination1whenthedemolitionperiodischanged.
Figure9.FinalimpactpercentagesofCombination2whenthedemolitionperiodischanged.
70
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
70
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
Figure 9. Final impact percentages of Combination 2 when the demolition period is changed.
Sustainability2023,15,xFORPEERREVIEW18of25
Figure10.FinalimpactpercentagesofCombination3whenthedemolitionperiodischanged.
70
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
10
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
Figure 10. Final impact percentages of Combination 3 when the demolition period is changed.
Sustainability 2023,15, 14382 18 of 25
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Figure10.FinalimpactpercentagesofCombination3whenthedemolitionperiodischanged.
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
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Finalimpactpercentage
Time(year)
1:SMR=6,MDR=10,LGR=14
2:SMR=8,MDR=12,LGR=15
3:SMR=9,MDR=13,LGR=16
Figure 11. Final impact percentages of Combination 4 when the demolition period is changed.
The results confirm that the final impact percentage decreases when the operation
time decreases. This is in line with Ebrahimi [
48
] in that the equipment’s impact on
the environment depends on the time usage of the equipment. New technology, for
excavators and hydraulic splitters in particular, is required to perform the tasks with the
same performance in a shorter time. Some innovations are offered to dig and grade faster,
eliminate guesswork, reduce fuel consumption, enhance operator comfort, and improve
safety [
49
]. Examples of technologies are using cameras to enhance site productivity and
safety and having cylinder pressure data and machine sensors to calculate material weight
while the excavator works continuously [49].
In summary, the simulation results reveal that Combination 4, green demolition using
demolition robots, incurs the lowest final impact percentage of less than 20%, four times
less than other combinations. Using demolition robots in Combination 4 provides various
advantages over traditional methods.
•
Its size is more compact than its traditional counterparts, such as excavators and
mechanical jackhammering, while its power is much greater.
•It can work continuously without interruption or breaks.
•
The remote-controlled aspect of demolition robots provides additional control to
features, thus enhancing flexibility and efficiency. It also ensures the safety of operators
as it can be controlled from a safe distance from the demolition sites.
•It can engage in high-risk demolition operations and reduce casualties.
•It requires fewer workers, resulting in reduced costs and more safety.
•
It is environmentally friendly and solves many environmental issues, such as noise,
dust, and vibration [5,50].
•
It reduces the time require for demolition, thereby speeding up the redevelopment
process.
In case Combination 4 is not yet available, Combination 1 generates the lowest final
impact percentage, followed by Combination 2 and 3, respectively. This combination
Sustainability 2023,15, 14382 19 of 25
causes the lowest CO
2eq
emission and energy consumption percentages (considered global
environmental impacts) but the highest noise, dust, and heat percentages (considered local
environmental impacts). As the dust issue is becoming a severe concern in Thailand, the
work rate of jackhammers (i.e., a key tool in this combination) may be adjusted and replaced
by other tools, if possible [
51
]. Pusapukdepop and Pengsaium [
51
] stated that the dust risks
in demolition depend on the demolition volume, the height of the buildings, the demolition
methods, and the disposal methods. The Department of Trade and Industry [
52
] suggested
using wet foam to catch the dust generated during collapse to reduce the dust produced
when a building is demolished.
6. Discussion and Conclusions
Bangkok’s population and development growth has generated an increasing demand
for more housing units and development, leading to more building demolition to build
new residential units. Concrete structure demolition is a complicated process that needs
careful planning and management. Using different demolition tools incurs other impacts
on the environment on global and local scales. It is necessary to optimize the selection of
suitable tool combinations for safe demolition processes that have minimal impact on the
surrounding environment. In this study, the SD model was developed with key factors,
such as the number of townhouses to be demolished, the sizes of the townhouses, various
environmental impacts, demolition periods, and different combinations of demolition tools,
to examine the environmental impact of different tool combinations in the long term. Four
combinations of demolition tools were considered for townhouse demolition. Combination
1 combines the use of excavators, jackhammers, and flame cutters. Combination 2 considers
excavators, jackhammers, and hydraulic splitters. Combination 3 considers excavators and
hydraulic splitters, while Combination 4 uses demolition robots and hydraulic splitters in
the demolition process. Five environmental impacts in the demolition process are listed:
CO
2eq
emissions, energy consumption, noise, dust, and heat, with the importance weights
of 21.7, 6.3, 1.3, 1, and 1, respectively.
The simulation results revealed that Combination 4, green demolition using demolition
robots, incurs the lowest final impact percentage. In Combination 4, energy consumption
and CO
2eq
emissions highly contribute to the final impact percentage. However, these two
impacts are lower compared with other combinations. This is consistent with Jing et al. [
5
]
in that green demolition reduces 8.5% of CO
2
emissions compared to traditional processes.
In case Combination 4 is not yet available, Combination 1 generates the lowest final impact
percentage, followed by Combination 2 and 3, respectively.
The sensitivity analysis was performed to validate the developed SD model and
suggest ways to reduce the environmental impact in the long term. In this study, the
demolition periods for small-, medium-, and large-sized townhouses were changed to
examine the final impact percentage of each tool combination. The results confirm the
validity of the developed SD model and agree that shorter demolition periods result in lower
final impact percentages. Various technologies, such as soundless chemical demolition,
demolition robots, and electric methods, may reduce the demolition time and remain
efficient. These can result in a quicker turnaround for land to be available for new projects,
which can be advantageous for urban development and land use planning.
The developed SD model may be used as a guideline for demolition companies to
plan for demolition tools used in townhouse demolition to minimize the environmental
impact in the long term. Economic analysis may be performed together with environmental
analysis to select the best strategies for long-term implementation. This research study has
some limitations. The secondary data used in the model’s development were collected from
the literature in developed and developing countries and are not specific to the Thai context.
The primary data were collected from a limited number of experts in the construction
industry. The importance weights of the environmental impacts were acquired from the
literature review and may be adjusted. Townhouses are used in building demolition. Other
types of buildings may be considered.
Sustainability 2023,15, 14382 20 of 25
Author Contributions:
Conceptualization, B.M. and T.C.; methodology, B.M. and T.C.; validation,
B.M. and T.C.; writing—original draft preparation, B.M.; writing—review and editing, T.C. All
authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Informed Consent Statement:
Informed consent was obtained from all subjects involved in
the study
.
Data Availability Statement: Not applicable.
Acknowledgments:
The first author received an Excellent Foreign Students (EFS) scholarship pro-
vided by the Sirindhorn International Institute of Technology (SIIT), Thammasat University.
Conflicts of Interest: The authors declare no conflict of interest.
Abbreviations
Abbreviation Description Unit
BHU Bangkok housing units
units/year
CO2eqDR4 CO2equivalent emissions of demolition robots used in Combination 4 kgCO2eq
CO2eqEX1 CO2equivalent emissions of excavators used in Combination 1 kgCO2eq
CO2eqEX2 CO2equivalent emissions of excavators used in Combination 2 kgCO2eq
CO2eqEX3 CO2equivalent emissions of excavators used in Combination 3 kgCO2eq
CO2eqJH1 CO2equivalent emissions of jackhammers used in Combination 1 kgCO2eq
CO2eqJH2 CO2equivalent emissions of jackhammers used in Combination 2 kgCO2eq
CO2eqHS2 CO2equivalent emissions of hydraulic splitters used in Combination 2 kgCO2eq
CO2eqHS3 CO2equivalent emissions of hydraulic splitters used in Combination 3 kgCO2eq
CO2eqHS4 CO2equivalent emissions of hydraulic splitters used in Combination 4 kgCO2eq
DEX1 Dust of excavators used in Combination 1 mg/m3
DEX2 Dust of excavators used in Combination 2 mg/m3
DEX3 Dust of excavators used in Combination 3 mg/m3
DJH1 Dust of jackhammers used in Combination 1 mg/m3
DJH2 Dust of jackhammers used in Combination 2 mg/m3
F1C1 Final impact percentage of Combination 1 %
LTHP Large townhouses portion from total townhouses
units/year
NEX1 Noise of excavators used in Combination 1 decibels
NEX2 Noise of jackhammers used in Combination 2 decibels
NEX3 Noise of excavators used in Combination 3 decibels
NJH1 Noise of jackhammers used in Combination 1 decibels
MAXTCO2eq Maximum CO2equivalent emissions kgCO2eq
MAXTD Maximum dust mg/m3
MAXTH Maximum heat kJ
MAXTN Maximum noise decibels
MAXTP Maximum primary energy consumption kgoe
MTHP Medium townhouses portion from total townhouses
units/year
PEX1 Primary energy consumption of excavators used in Combination 1 kgoe
PEX2 Primary energy consumption of excavators used in Combination 2 kgoe
PEX3 Primary energy consumption of excavators used in Combination 3 kgoe
PDR4 Primary energy consumption of demolition robots used in Combination 4 kgoe
PFC1 Primary energy consumption of flame cutters used in Combination 1 kgoe
PJH1 Primary energy consumption of jackhammers used in Combination 1 kgoe
PJH2 Primary energy consumption of hydraulic splitters used in Combination 2 kgoe
PJH3 Primary energy consumption of hydraulic splitters used in Combination 3 kgoe
PJH4 Primary energy consumption of hydraulic splitters used in Combination 4 kgoe
STHP Small townhouses portion from total townhouses
units/year
TCO2eq1 Total CO2equivalent emissions of Combination 1 kgCO2eq
TCO2eq2 Total CO2equivalent emissions of Combination 2 kgCO2eq
TCO2eq3 Total CO2equivalent emissions of Combination 3 kgCO2eq
TCO2eq4 Total CO2equivalent emissions of Combination 4 kgCO2eq
TCO2eq1N Total CO2equivalent emissions percentage of Combination 1 %
Sustainability 2023,15, 14382 21 of 25
TD1 Total dust of Combination 1 mg/m3
TD1N Total dust percentage of Combination 1 %
TD2 Total dust of Combination 2 mg/m3
TD3 Total dust of Combination 3 mg/m3
TD4 Total dust of Combination 4 mg/m3
TH1 Total heat of Combination 1 kJ
TH1N Total heat percentage of Combination 1 %
TH2 Total heat of Combination 2 kJ
TH3 Total heat of Combination 3 kJ
TH4 Total heat of Combination 4 kJ
THD Townhouses demolished
Units/year
THU Townhouse units
Units/year
TN1 Total noise of Combination 1 decibels
TN2 Total noise of Combination 2 decibels
TN3 Total noise of Combination 3 decibels
TN4 Total noise of Combination 4 decibels
TP1 Total primary energy consumption of Combination 1 kgoe
TP1N Total primary energy consumption percentage of Combination 1 %
TP2 Total primary energy consumption of Combination 2 kgoe
TP3 Total primary energy consumption of Combination 3 kgoe
TP4 Total primary energy consumption of Combination 4 kgoe
Yr Count year years
Appendix A
SD Model Equations
BHU =2400540 ×1.0256yr−1
THU =0.51 ×BHU
THD =0.1 ×T HU
STHD =ST HP ×THD
LTHD =LTHP ×T H D
MT HP =1−(ST HP +LTH P)
MT HD =MT HP ×THD
CO2eqEX1=2.025 ×PEX1×0.5[(ST HD ×64)+(MT HD ×96)+(LTHD ×128)]
CO2eqJ H1=0.495 ×PJH1×[(ST HD ×2×64)+(MTHD ×4×96 )+(LTHD ×6×128 )]
CO2eqFC1=0.495 ×PFC1×[(ST H D ×2×64)+(MTHD ×2×96)+(LTH D ×4×128)]
TCO1eq1=CO2eqEX1+CO2eqJH1+CO2eqFC1
TCO2eq2=CO2eqEX2+CO2eqJH2+CO2eqHS2
Sustainability 2023,15, 14382 22 of 25
TCO3eq3=CO2eqEX3+CO2eqHS3
TCO4eq4=CO2eqDR4+CO2eqHS4
MAXTCO2eq =MAX(TCO2eq1, TCO2eq2, TCO2eq3, TCO2eq4)
TCO2eq1N=TCO2eq1/MAXTC02eq ×100
PEXI =210 ×0.086 ×0.5[(STHD ×64)+(MT H D ×96)+(LTHD ×128)]
PJH1=2.2 ×1.952 ×0.4[(ST H D ×2×64)+(MTHD ×4×96)+(LTH D ×6×128)]
PFC1=1.5 ×1.952 ×0.1[(STHD ×2×64)+(MT HD ×2×96)+(LTH D ×4×128)]
TP1=PEX1+PJ H1+PFC1
TP2=PEX2+PJ H2+PHS2
TP3=PEX3+PHS3
TP4=PDR4+PHS4
MAXTP =MAX(T P1, T P2, T P3, TP4)
TP1N=TP1/M AXTP ×100
NEX1=112 ×0.5[(ST HD ×64)+(MT H D ×96)+(LTHD ×128)]
NJ H1=113 ×0.4[(ST HD ×2×64)+(MTHD ×4×96)+(LTHD ×6×128)
TN1=NEX1+N J H1
TN2=NEX2+N J H2
TN3=NEX3
TN4=0
MAX TN =M AX (TN1, T N2, TN3, TN4)
Sustainability 2023,15, 14382 23 of 25
TN1N=TN1/MAXTN ×100
DEX1=1.4 ×0.5[(ST HD ×64)+(MTHD ×128)+(LTH D ×128)]
DJH1=3.4 ×0.4 [(ST H D ×2×64)+(MTHD ×4×96)+(LTH D ×6×128)]
TD1=DEX1+D J H1
TD2=DEX2+D J H2
TD3=DEX3
TD4=0
MAXTD =MAX(T D1, TD2, TD3, TD4)
TD1N=TD1/MAXTD ×100
HFC1=850 ×0.1[(ST H D ×2×64)+(MTHD ×2×96)+(LTH D ×4×128)]
TH1=HFC1
TH2=0
TH3=0
TH4=0
MAXTH =MAX(TH1, T H2, TH3, TH4)
TH1N=T H1/MAXTH ×100
FIC1=((TCO2eq1N×21.7)+(TP1N×6.3)+(TN1N×1.33)+(T D1N×1)+(T H1N×1))/31.3
References
1.
Thailand Essential, Thailand Construction Market Report Overview. 2022. Available online: https://www.marketresearch.com/
seek/Construction-Thailand/105/1245/1.html (accessed on 3 September 2023).
2.
National Housing Authority (NHA). Data Collection Survey on Housing Sector in Thailand; Japan International Cooperation Agency
(JICA), International Development Center of Japan, Inc.: Tokyo, Japan, 2013.
3.
Klinmalai, S.; Kiyoko, K. Characteristic of sustainable location for townhouse development in Bangkok and greater metropolitan
region, Thailand. In Spatial Planning and Sustainable Development; Springer: Dordrecht, The Netherlands, 2013. [CrossRef]
4.
The Constructor. Demolition Methods and Process for Building Structure. Building Technology Guide. 2022. Available online: https:
//theconstructor.org/structures/demolition-methods- process-buildings-structures/13941/ (accessed on 3 September 2023).
5.
Jing, Z.; Wenzhong, Z.; Chonghao, X.; Yiqiang, S. Green Demolition of Reinforced Concrete Structures: Review of Research
Findings. Glob. J. Res. Eng. E Civ. Struct. Eng. 2019,19, 1–18.
Sustainability 2023,15, 14382 24 of 25
6. Shweta, O.R.; Khandvi, P.V. Demolition of Building an overview. Int. J. Adv. Eng. Res. Dev. 2014,1, 131–139.
7.
Singh, V.; Rawat, V.; Chavan, O.; Jadhav, R. Selection of Suitable Techniques, Scope and Regulations for Demolition of Rcc
Building. Int. J. Res. Eng. Appl. Manag. 2018, 180–184.
8.
Takashima. Demolition Project Report. 2023. Available online: https://courses.nus.edu.sg/course/bdgchewm/PF210
7%20%20Demolition/Demolition%20Project%20Report%20Tutorial%204%20Presentation%20Group%202.pdf (accessed on
3 September 2023).
9. Rexcon. Building Demolition. 2022. Available online: https://rexcon.business.site/ (accessed on 3 September 2023).
10.
Aymen, A. Guidelines for Civil Structures Demolition Method selection to enhance Environmental Protection. Int. J. Emerg.
Trends Eng. Res. 2020,8, 11822020.
11.
Abdullah, A.; Anumba, C.J. Decision criteria for the selection of demolition techniques. In Proceeding of the Second International
Postgraduate Research Conference, Salford, UK, 11–12 April 2002; Blackwell Publishers: Oxford, UK, 2002; pp. 410–419.
12.
Anumba, J.; Abdulla, A.; Ruika, K. An Integrated System for Demolition Techniques Selection. Archit. Eng. Des. Manag.
2008
,
4, 130–148. [CrossRef]
13.
Oryza, S.; Wahyu, T.; Munif, A. Selection Model of Building Demolition Method Based on Expert System. In Proceedings of the
Third International Conference on Sustainable Innovation 2019—Technology and Engineering, Yogyakarta, Indonesia, 30–31 July
2019; p. 187.
14.
Macrotrends. Bangkok, Thailand Metro Area Population 1950–2023. Available online: https://www.macrotrends.net/cities/2261
7/Bangkok/population (accessed on 3 September 2023).
15.
Bangkok Post. Townhouse Revival. 2023. Available online: https://www.bangkokpost.com/business/1473689/townhouse-
revival (accessed on 3 September 2023).
16. Risland Thailand. Housing Project by Type. 2023. Available online: https://risland.co.th/en/ (accessed on 3 September 2023).
17. Poombete, T.; Krichkanok, S.; Tusanee, T. Waste generated in high-rise buildings. Construction. A current situation in Thailand.
Energy Procedia 2017,138, 411–416.
18. Abdullah, A. Intelligent Selection of Demolition Techniques. Ph.D. Thesis, Loughborough University, Leicestershire, UK, 2003.
19.
Ronix, Rotary and Demolition Hammers. 2023. Available online: https://ronixtools.com/en/power-tools/rotary-demolition-
hammers/ (accessed on 3 September 2023).
20.
Thomas, S.; LaGuardia, P.E. Concrete Decontamination and Demolition Methods; Nuclear Energy Services, Inc.: Danbury, CT,
USA, 2013.
21.
Hemlata, P.; Verma, J.; Surya, S. Environmental Issues: Local, Regional, and Global Environmental Issues; Society of Biological Sciences
and Rural Development: Prayagraj, India, 2020; pp. 234–246.
22. Ram, S.; Pradeep, S. Global Environmental Problem. In Principles and Applications of Environmental Biotechnology for a Sustainable
Future; Springer: Singapore, 2020; pp. 13–41.
23.
Chooi, M.; Takeshi, F.; Chin, S. Environmental Impacts of Construction and Demolition Waste Management Alternatives. Chem.
Eng. Trans. 2018,17, 131–139.
24.
Fantozzi, F.; Gargari, C.; Rovai, M.; Salvadori, G. Energy upgrading of residential building stock: Use of life cycle cost analysis to
assess interventions om social housing in Italy. Sustainability 2019,11, 1452. [CrossRef]
25.
Abraham, J.; Saravanakumar, R.; Ebenanjar, P.E.; Elango, K.S.; Vivek, D.; Anandaraj, S. An experimental study on concrete block
using construction demolition waste and life cycle cost analysis. Mater. Today Proc. 2022,6, 1320–1324. [CrossRef]
26.
Coelho, A.; Brito, J. Environmental analysis of a construction and demolition waste recycling plant in Portugal—Part I: Energy
consumption and CO2emissions. J. Waste. Manag. 2013,33, 1258–1267. [CrossRef]
27. Jones, M.J.; Smith, J.A. A System Dynamics Model of the Demolition Industry. J. Constr. Eng. Manag. 2005,131, 1201–1209.
28.
Brown, R.L.; Smith, J.C. A System Dynamics Approach to the Selection of Demolition Methods. J. Constr. Eng. Manag.
2012
,
133, 1083–1092.
29. Jones, M.J.; Smith, J.C. The Impact of Demolition Methods on the Environment. Constr. Build. Mater. 2007,21, 2559–2567.
30. Brown, R.L.; Smith, J.C. The Safety of Demolition Workers. Proc. Inst. Civ. Eng. Civ. Eng. 2015,160, 23–32.
31.
Chadegani, A.; Salehi, H.; Yunus, M.; Farhadi, H.; Fooladi, M.; Farhadi, M. A comparison between two main academic literature
collections: Web of science and Scopus Databases. Asian Soc. Sci. 2017,9, 18–26. [CrossRef]
32. Burnham, J. Scopus database: A review. Biomed. Digit. Libr. 2006,3, 1. [CrossRef]
33.
Ali, A.; Ahmad, M.; Yusup, Y. Issues, Impacts, and Mitigations of Carbon Dioxide Emissions in the Building Sector. Sustainability
2020,12, 7427. [CrossRef]
34.
Sterman, J.D. System Dynamics Modeling for Project Management; Sloan School of Management, Massachusetts Institute of
Technology: Cambridge, MA, USA, 1992.
35.
Doan, T.; Chinda, T. Modeling Construction and Demolition Waste Recycling Program in Bangkok: Benefit and Cost Analysis. J.
Constr. Eng. Manag. 2016,142, 05016015. [CrossRef]
36.
Ding, Z.; Gong, W.; Li, S.; Wu, Z. System dynamics versus Agent-based modeling: A review of complex simulation in construction
waste management. Sustainability 2018,10, 2484. [CrossRef]
37.
Liu, J.; Liu, Y.; Wang, X. An environmental assessment model of construction and demolition waste based on system dynamics: A
case study in Guangzhou. Environ. Sci. Pollut. Res. 2020,27, 37237–37259. [CrossRef]
Sustainability 2023,15, 14382 25 of 25
38.
Lampyb, B.; Sound Power Level of Powered Mechanical Equipment. Development of Road Quarry Site Investigation, Design,
and Construction. 2014. Available online: https://www.epd.gov.hk/eia/register/report/eiareport/eia_2342015/Pdf/EIA/
Appendix/Appendix%205.2.pdf (accessed on 3 September 2023).
39.
Kirkeskov, L.; Hanskov, D.; Brauer, C. Total and respirable dust exposures among carpenters and demolition workers during
indoor work in Denmark. J. Occup. Med. Toxicol. 2017,11, 45. [CrossRef]
40.
CEIC. Thailand Energy and Carbon Dioxide per Electricity Generation; Energy Policy and Planning Office, Ministry of Energy:
Bangkok, Thailand, 2022.
41.
Vevor. Demolition Tools and Equipment. 2023. Available online: https://eur.vevor.com/demolition-tools-equipment-c_10984
(accessed on 3 September 2023).
42.
Hassanean, J.; Weizhuo, L.; Thomas, O. Quantification of Energy Consumption and Carbon Dioxide Emissions During Excavator
Operations. In Proceedings of the 25th EG-ICE International Workshop 2018, Lausanne, Switzerland, 10–13 June 2018.
43.
Replicon. Construction Work Time. 2023. Available online: https://www.replicon.com/time-attendance/construction-time-
tracking/ (accessed on 3 September 2023).
44.
Dworkin, L. Sample Size Policy for Qualitative Studies Using In-Depth Interviews. Arch. Sex. Behav.
2012
,41, 1319–1320.
[CrossRef]
45.
Chontanawat, J. Relationship between Energy Consumption, CO
2
Emission and Economic Growth in ASEAN: Cointegration
and Causality Model. In Proceedings of the 6th International Conference on Energy and Environment Research, ICEER 2019,
University of Aveiro, Aveiro, Portugal, 22–25 July 2020.
46.
Bala, K.; Arshad, M.; Noh, M. System Dynamics; Scenario planning and modeling series; Springer: Berlin/Heidelberg, Germany,
2016; pp. 149–162.
47. Forester, J.; Senge, M. Test for building confidence in system dynamics modelling. TIMS Stud. Manag. Sci. 1980,14, 209–228.
48.
Ebrahimi, B.; Wallhaum, H.; Jakobsen, D.; Booto, K. Regionalized environmental impacts of construction machinery. Int. J. Life
Cycle Assess. 2020,25, 1472–1485. [CrossRef]
49.
Conexpo. 5 Excavator Technologies to Improve Your Bottom Line. 2022. Available online: https://www.conexpoconagg.com/
news/5-excavator-technologies-to-improve-your-bottom-li (accessed on 3 September 2023).
50.
Conjet. Advantages of a Robotic Demolition Machine. 2023. Available online: https://www.conjet.com/advantages-of-a-robotic-
demolition-machine/ (accessed on 3 September 2023).
51.
Pusapukdepop, J. Pengsaium, V. Measures to Reduce the Impact of Dust from Construction in Bangkok; St. Theresa International
College: Nakhon Nayok, Thailand, 2018. [CrossRef]
52.
Department of Trade and Industry. Dust Suppression System for Use in the Demolition of Buildings. 2004. Available online:
https://patentimages.storage.googleapis.com/2d/5d/e1/43721f38abbf4c/GB2396381A.pdf (accessed on 3 September 2023).
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