List of figures:
List of abbreviations:
Abstract:
The construction industry contributes 33% of global greenhouse emission (GHG). Therefore, it is
crucial to investigate the contribution of the machinery on site in order to control GHG
emissions. This study aims to investigate the carbon footprint due to construction machinery
used on site for a project of constructing a 2-story office building along with its parking lot. The
study is conducted within a life cycle assessment (LCA) frame of work and according to the
four-step ISO 14040:2006 guidelines. A site daily report was used to obtain a comprehensive list
of all machinery used on the site including the total number of machinery, duration of operation
as well as manufacturer and size/capacity of the machinery. These figures were then used to
calculate the carbon footprint of each machine. The results show that the hot spot is the crane. It
produced around 1064 metric ton CFP which is 10 times higher than the contribution of the
second largest contributor which is the excavator/backhoe. This leads to conclude that tackling
the crane’s emission can reduce the total carbon footprint of machinery on site significantly. This
study recommends replacing machinery that runs on fossil fuels with machinery that runs on
biofuels. As well as reducing the weight of the construction material/elements, where possible, in
order to reduce the demand for the crane. Hence, reducing the total carbon footprint.
Keywords: Carbon footprint, Life cycle assessment, construction, machinery, Greenhouse gases,
Emissions.
Introduction:
Background
Studies in the last 50 years have shown, with increasing accuracy, that CO2 has been increasing
rapidly in the atmosphere (Razali, 2016). Moreover, the chemical fingerprint in CO2 molecules
in the atmosphere indicates that fossil fuels combustion is driving the CO2 increase. 33% of this
increase is directly related to construction activity (Olivier et al, 2017).
The construction sector is extremely vital in any economy due to two main reasons. First, it
contributes directly to economic growth. The other main reason is that the construction sector
draws the main boundaries of growth for all other sectors. This is because other sectors such as
agriculture, industrial, commerce, etc, all require actual physical structures that are provided for
by the construction sector.
Due to its impact on the environment, and its importance to the economy, it is clearly necessary
to investigate construction activities’ contribution to GHG emissions in order to steer the
construction industry towards a more green and sustainable direction. This paper assesses the
carbon footprint contribution of the construction machinery used on a case study of the
construction of a two story office building with an adjacent parking lot.
Problem Statement:
The construction industry is a large contributor to global Green House Emissions (GHG). Within
the construction industry, major construction activities require the use of a wide variety of
machinery that mainly depends on fossil fuels as its main source of energy. Therefore, an
assessment of the GHG emission due to construction machinery is necessary in order to mitigate
these emissions and steer the construction industry in Malaysia towards a green, more
sustainable direction.
Objectives:
1) Estimate the amount of CO2 produced by various machinery used in construction
activities in Malaysia.
2) Determine the hotspot for machinery on site.
3) Analyze the impact of green solutions on GHG emissions in a construction site.
Literature Review
In Malaysia, the construction sector contributes approximately 14 billion RM to national GDP as
of 2018 (Department of statistics, Malaysia). Moreover, the construction industry in Malaysia is
moving towards lower GHG emission with emphasis on mitigating GHG emissions from
building, industries, machinery, transportation and land use (Razali et al, 2016).
Currently, the normal practice still involves cast in situ. Therefore, using machinery in
construction significantly contributes to the global carbon footprint. This emphasizes the
significance of construction machinery to global GHG emissions.
Life Cycle Assessment
Life cycle assessment compares the full range of environmental effects of released GHG by any
product by assessing the stages of the life cycle of the product (Bilec et al, 2010). Life cycle
assessment includes the following five stages:
1) Sourcing.
2) Production.
3) Distribution.
4) Consumption.
5) End of life.
In a construction context, the final product is mainly the physical structure constructed
throughout the project. The sourcing refers to sourcing for construction materials such as
concrete, steel, wood, fine and course aggregate, etc. The production phase of construction refers
to the construction activities on site, or production operations in plants and factories that are
related to construction such as concrete plants and steel production factories. Distribution refers
to distribution of construction materials and structural elements by transporting such
materials/elements from quarry or plant to site. Finally, consumption of a construction product
refers to the use of a physical structure which mainly refers to heating and cooling. Finally, end
of life refers to the demolition or abandonment of the facility.
Scope of Work
The scope of work for this study covers GHG emissions due to machinery on site. This covers all
machinery and equipment such as cranes, excavation and compacting machinery, mixers, etc.
This is mainly the “production” phase of the life cycle.
Methodology:
Stage1: Data collection
In order to estimate the carbon footprint of construction machinery on site, various data need to
be collected such as type and number of machinery, duration of use for each machinery, and
engine rating. This data can be obtained primarily from site diaries, BQ or CPM of completed
projects.
Moreover, data on green alternative technologies and machinery is obtained by studying
literature, technical papers, reports and investigating available green construction technologies.
Stage 2: Life cycle assessment
This stage includes the environmental impact assessment and the determination of the hotspot.
The assessment is based on CO2 footprint of the machinery for each stage of the construction
cycle.
The life cycle assessment is performed according to the four-step ISO 14040:2006 guidelines:
1) Scope Definition:
The scope of this study is to assess the hotspots of CO2 footprint produced by
construction machinery at all stages of a construction project in a case study.
2) Life Cycle Inventory Analysis:
The analysis is based on:
i.
Engine rating of machinery.
ii.
Duration of working hours throughout a completed project.
iii.
Type of machinery: i.e. excavator, compactor, backhoe, etc.
The engine rating for each machinery is collected to calculate fossil fuel consumption
intensity rate.
3) Life Cycle Impact Assessment:
This assessment evaluates the significance of potential environmental impacts based on
CO2 footprint model developed by the Department of the Environment, Food and Rural
Affairs (DEFRA) of the United Kingdom. It involves three steps:
I.
Identifying the fuel mass consumption of machinery.
FMC = D0 * Er * FMR * 1 Liter
Where FMC: fuel mass consumption (L), D0: duration of operation (h), Er:
engine rating (kW/h), and FMR: fuel mass consumption rate of 0.24 kg/kWh
(DEFRA recommended value).
II.
Calculating CO2 footprint of the embodied energy (EE):
CFEE = FMC * CO2DF
Where CFEE: carbon footprint of embodied energy (tons fossil CO2e), and
CO2DF: carbon dioxide equivalent factor of diesel of 0.0031761 ton CO2e
(DEFRA recommended value).
III.
Calculating the total carbon footprint.
CF = CFEE + CFT
Where CF = total carbon footprint, and CFT: carbon footprint resulting from fuel
transport (ton CO2e).
However, carbon footprint due to transportation is out of the scope of this study
and therefore, not considered in total carbon footprint.
4) Interpretation:
Data related to various machinery is compared together in order to identify the largest
contributors to global GHG emissions (hot spot).
Stage 3: Comparison:
Possible green solutions are compared to existing practice to evaluate feasibility and efficiency
of proposed solutions.
Results & Discussion:
Contact has been made with engineer Ihsan from JFE ENGINEERING SDN BHD. He provided
site diary (daily report) listing all construction equipment used for the entire duration of a
completed project. The project is construction of a 2 story office building and warehouse facility
which took approximately 13 months to complete.
The data provided in the diary include number of machinery used on site and the duration of
operation. In order to ensure accuracy, further details regarding the machinery such as make,
model, and size/capacity is obtained after conducting meetings with engineer Ihsan of JFE
ENGINEERING SD BHD. Moreover, the engine rating of each machinery is obtained from its
respective specifications sheet. Whenever the specification sheet is not available, engine rating of
an equivalent machine with similar size/capacity is used.
After data collection is completed, analysis in terms of total working hours, engine rating and
carbon footprint for all of the machinery is conducted, as previously explained, according to the
ISO 14040: 2006 guidelines. Figure () lists all construction machinery on site and their
respective duration of operation.
Some of the machinery run on electric power or batteries such as the pressure recorder and the
spot light, while some have a very low power demand such as the cutter. These types of
machinery have no to little carbon footprint and therefore, these machines are eliminated from
the study as the study’s objective is to identify the hot spot.
Fig () lists all significant machinery on site along with its respective duration of operation in
days, then converted into hours based on a 7-hour work day.
By observing the data in figure (), it is clear that the hot spot for this case study is the crane. The
20 MT crane produces 10 times more CO2 than the next largest contributor on site, which is the
excavator. By analyzing the three variables used in the calculation which are duration, engine
rating and fuel mass consumption, the 20 MT crane stands out by having the longest duration of
operation, the highest engine rating and the highest fuel consumption. This explains why the
crane produces, by far, the highest carbon footprint amongst all other machinery on site.
In general, all machinery on site can be categorized into three main categories in terms of carbon
footprint contribution:
1) Category 1: The actual hot spot identified, which is the crane. Characterized by high
power requirements (>1000KW) due to handling heavy weight and long, continuous
working hours and high fuel consumption.
2) Category 2: Earthwork machinery such as piling machine, excavator, backhoe, back
pusher in addition to concrete mixers. Characterized by medium power requirement
(within 50-300 KW) with varying working hours.
3) Category 3: Equipment with low power requirement (<50 KW) and low GHG emission
such as powder float machine, small size compactors, cutters etc.
Conclusion:
In conclusion, this study shows that in assessing the carbon footprint of construction machinery
on site, the crane stands out as the hot spot by far. This is due to high fuel demand, continuous
operation, and high power demand. Reducing the GHG emissions due to crane operation will
significantly limit the GHG emissions due to construction machinery on site. Other construction
machinery, mainly earthwork machinery, with moderate power demand do contribute to GHG
emissions but to a much lower extent.
Recommendation:
Carbon Footprint Per Equipment
CFP (Metric Ton)
1500
1064
1000
500
93
6
3
0
40
3
10
24
EQUIPMENT
Crane 20 MT
Excavator/Backhoe
Concrete Mixer
Generator
Piling Machine
Compactor
Back Pusher
Skylift
Powder Float Machine
Diamond Cutter
1
1
Carbon Footprint Per Equipment
CFP (Metric Ton)
100
93
80
60
40
40
24
20
6
3
0
EQUIPMENT ON SITE
Crane 20 MT
Excavator/Backhoe
Concrete Mixer
Generator
Piling Machine
Compactor
Back Pusher
Skylift
Powder Float
Machine
Diamond Cutter
10
3
1
1
EQUIPMENT (excluding Crane 20 MT)
Excavator/Backhoe
Concrete Mixer
Generator
Piling Machine
Compactor
Back Pusher
Skylift
Powder Float Machine
Diamond Cutter
Duration
(HRS)
Er
(Kw)
FMR
(Kg/Kwh)
FMC
(Liter)
CDEF
CFP
(Metric Ton)
1323
1078
1589
301
231
35
245
511
1055
112.5
4.8
12.2
227
99
51.5
60
0.24
0.24
0.24
0.24
0.24
0.24
0.24
0.24
334983.6
29106
1830.6
881.4
12584.9
845.5
3028.2
7358.4
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
1064
93
6
3
40
3
10
24
294
28
3.7
9.7
0.24
0.24
261.1
65.2
0.0031761
0.0031761
1
1
EQUIPMENT ON SITE
Crane 20 MT
Excavator/Backhoe
Piling Machine
Skylift
Back Pusher
Concrete Mixer
Generator
Compactor
Powder Float
Machine
Diamond Cutter
EQUIPMENT ON SITE
Concrete Mixer
Crane 20 MT
Excavator/Backhoe
Skylift
Generator
Powder Float
Machine
Back Pusher
Piling Machine
Compactor
Diamond Cutter
Duration
(HRS)
Er
(Kw)
FMR
(Kg/Kwh)
FMC
(Liter)
CDEF
CFP
(Metric Ton)
1323
1078
231
511
245
1589
301
35
1055
112.5
227
60
51.5
4.8
12.2
99
0.24
0.24
0.24
0.24
0.24
0.24
0.24
0.24
334983.6
29106
12584.9
7358.4
3028.2
1830.6
881.4
845.5
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
1064
93
40
24
10
6
3
3
294
28
3.7
9.7
0.24
0.24
261.1
65.2
0.0031761
0.0031761
1
1
Duration
(HRS)
Er
(Kw)
FMR
(Kg/Kwh)
FMC
(Liter)
CDEF
CFP
(Metric Ton)
1589
1323
1078
511
301
4.8
1055
112.5
60
12.2
0.24
0.24
0.24
0.24
0.24
1830.6
334983.6
29106
7358.4
881.4
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
6
1064
93
24
3
294
245
231
35
28
3.7
51.5
227
99
9.7
0.24
0.24
0.24
0.24
0.24
261.1
3028.2
12584.9
845.5
65.2
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
1
10
40
3
1
EQUIPMENT ON SITE
Crane 20 MT
Piling Machine
Excavator/Backhoe
Compactor
Skylift
Back Pusher
Generator
Diamond Cutter
Concrete Mixer
Powder Float
Machine
EQUIPMENT ON SITE
Crane 20 MT
Piling Machine
Excavator/Backhoe
Skylift
Back Pusher
Concrete Mixer
Generator
Compactor
Powder Float
Machine
Diamond Cutter
Duration
(HRS)
Er
(Kw)
FMR
(Kg/Kwh)
FMC
(Liter)
CDEF
CFP
(Metric Ton)
1323
231
1078
35
511
245
301
28
1589
1055
227
112.5
99
60
51.5
12.2
9.7
4.8
0.24
0.24
0.24
0.24
0.24
0.24
0.24
0.24
0.24
334983.6
12584.9
29106
845.5
7358.4
3028.2
881.4
65.2
1830.6
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
1064
40
93
3
24
10
3
1
6
294
3.7
0.24
261.1
0.0031761
1
Duration
(HRS)
Er
(Kw)
FMR
(Kg/Kwh)
FMC
(Liter)
CDEF
CFP
(Metric Ton)
1323
231
1078
511
245
1589
301
35
1055
227
112.5
60
51.5
4.8
12.2
99
0.24
0.24
0.24
0.24
0.24
0.24
0.24
0.24
334983.6
12584.9
29106
7358.4
3028.2
1830.6
881.4
845.5
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
0.0031761
1064
40
93
24
10
6
3
3
294
28
3.7
9.7
0.24
0.24
261.1
65.2
0.0031761
0.0031761
1
1
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