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\begin{document}

\title{Energy And Buildings Template}



\author[1]{Shreyans Surana}%
\affil[1]{Affiliation not available}%


\vspace{-1em}



  
  \date{May 05, 2024}


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\selectlanguage{english}
\begin{abstract}
Environmental concerns are a big threat to almost all the parts of most
of the countries in the world, especially with the growing size of
infrastructure. There is a need for attention towards structures with
respect to their impact on the environment. The present study is an
attempt to assess the ecological imbalance, environmental impacts, and
reduction in the overall lifetime of the buildings. Largely, the
ecological imbalance is due to the emission of Carbon Dioxide (CO2) into
the atmosphere which triggers global warming. The present study also
uses Life Cycle Assessment (LCA) as a tool to address the major
environmental concerns in the construction of residential buildings.
SimaPro 8.4 is used to assess and verify the overall performance of the
project in terms of its maintenance and quality. Also, the amount of
CO\textsubscript{2} generated due to use of machinery for construction
was found to be 3485.01 and the CO\textsubscript{2} emissions due to the
manufacturing of building materials were 18629.021 tonnes and were
compared with alternate databases. The percentage difference in the
value of CO2 emissions when an alternate database was used, was found to
be 27\%. The embodied energy associated with this building was also
calculated and it was found to be 15.65 TJ. An actual building case
study constructed using pure cement was chosen to apply the concepts of
LCA and compare the results with the alternative materials.~

\par\null%
\end{abstract}%



\sloppy




\section*{1. Introduction}

{\label{381896}}

The construction sector is damaging the environment by being the primary
contributor to generating Green House Gases (GHG). GHG emissions are
responsible for global warming. Carbon Dioxide (CO\textsubscript{2}) is
the principal GHG. The rampant growth of construction sector has
therefore led to an alarming increase in global warming. As per a report
by the UK Green Building Council, the CO\textsubscript{2} content in the
atmosphere is estimated to be doubled by 2100. Drainage of natural
resources, environmental damage, and GHG emissions have become driving
factors for initiation of sustainable construction practices. As per
C.K. Chau et al. 2015, Life cycle study comprises of three
sub-categories: Life cycle assessment (LCA), Life cycle energy
assessment (LCEA), and Life cycle carbon emission assessment
(LCCO\textsubscript{2}A).

The building sector accounted for nearly 40\% of the world's energy
consumption, 30\% of raw material use, 25\% of solid waste, 12\% of land
use, and 33\% of the related global greenhouse gas (GHG) emissions
{[}SBCI, UNEP 2009{]}. As per the latest report by India Environmental
Change {[}Jos G.J. Olivier et al., 2016{]}, net annual CO2 emission for
India during 2015 increased to 2.47 billion tonnes which were 5.1\% more
than in 2014. Energy from fossil fuels consumed in the construction and
operation of buildings accounts for approximately half of the UK's
emissions of carbon dioxide {[}Ben Stubbs, 2008{]}. As concluded by Cass
and Mukherjee (2011), 90\% of GHG emissions throughout the construction
phase were due to the production of materials. For India alone, CO2
emissions from cement and steel production increased by 4.9\% and 2.4\%
for the year of 2015 as compared to 2014 {[}Ben Stubbs, 2008{]}.

Hong et al. 2014, analyzed GHG emissions during the construction phase
of a case study building in China and concluded that building material
production and transportation, on-site electricity usage were three of
the greatest contributors for GHG emissions. Atmaca et al. 2015
concluded that the operational phase accounted for 79-84\% of total
energy requirements and 86-93\% of total CO2 emissions, over a lifespan
of 50 years, for a residential building each in a rural and urban area
of Gaziantep (Turkey). As concluded by Bribi\selectlanguage{ngerman}án et al., building
materials are the second most energy consuming for a residential
building after heat consumption during the operational phase. Seo et al.
2016, concluded that, for a building complex, materials production
accounted for 94.3\% of the net CO2 emission and CO2 emissions from the
material transportation and on-site construction were merely 2.4\% and
4.2\% of the total emissions, respectively. They also concluded that
choice of input materials and construction process plays a vital role in
reducing CO2 emissions.

Bribián et al. 2011, concluded that the impact of construction materials
can be significantly reduced by substituting the use of finite natural
resources for waste generated in other production processes, preferably
available locally. As concluded by Bansal et al. 2014, the use of
autoclaved aerated blocks (AAC) instead of burnt clay bricks in the
construction of a four storied building proved to be more energy
efficient. As per Ortiz et al. 2009, the application of LCA is essential
for in building and construction sector and can be utilized as a
decision-making tool in the construction sector. As concluded by Takano
et al 2015, the life cycle energy efficiency increases as the
geometrical factors become better for ex. perimeter to area ratio. They
also concluded that life cycle energy efficiency of a building increases
as the number of floors and stories increase. As concluded by Takano et
al 2015, the energy differences between alternate materials were more
prominent in the production stage of the building and also that use of
recyclable materials greatly influenced the life cycle energy of the
building.

\section*{2. Objective of the study}

{\label{486493}}

\section*{}

{\label{188453}}

Life cycle accounting of any process or a product is imperative as it
addresses the parameters in the process that impact or~contributes the
most towards environmental deterioration. Given the lack of studies
conducted on life cycle accounting in the Indian context, this study
aims at setting an illustration for a typical residential building in
India. This study also identifies the issues associated with a life
cycle study during various phases and the possible alternatives that can
be suggested. Finally, the study suggests alternate construction
materials that can be used to reduce the net impact during the process.
An~eight-storey residential apartment building, under its final stage of
construction, at the Hyderabad Campus of BITS Pilani was chosen for this
study to address the following objectives:

\begin{itemize}
\tightlist
\item
  Characterization and quantification of the environmental impacts of
  the various construction materials that have been used for the
  building.
\item
  Identifying the impacts of self-consolidating concrete mixes with
  waste materials like fly ash and (ground granulated blast furnace)
  GGBS.
\item
  Suggesting possible alternatives to reduce these impacts to reduce the
  overall life cycle impact of the overall process.
\item
  Quantify the greenhouse gas (GHG) emissions from construction
  materials and from the on-site machinery used during the construction
  phase.
\end{itemize}

\par\null

\section*{Methodology}

{\label{448908}}

As per C.K. Chau et al. 2015, life cycle study comprises of three
sub-categories:~ Life cycle Impact Assessment (LCIA),~ Life cycle energy
assessment (LCEA), and Life cycle carbon emission assessment (LCCO2A).
Any life cycle study is carried out for the~life time scale of a
product, that is, right from its birth to its demolition or dumping
phase. The life cycle phases of the building are illustrated in figure 1
(Flow diagram for the entire process). This scale includes the raw
materials extraction for the manufacturing of the product, their
transportation to the manufacturing plant, the manufacturing of the
materials, transportation of the materials to the construction site, the
construction phase, the operation or the use phase of the building,
maintenance and repair followed by the end-of-life or demolition phase
of the building. As there exists uncertainty when it comes to
operational phase and maintenance and repair, it becomes difficult to
quantify the impacts of these phases. The impacts during these phases
highly depend upon the nature of inhabitant. Hence, for this study, only
the cradle to gate system boundary has been investigated. This practice
of focusing on a particular area instead of the entire boundary system
is called streamlined LCA.~ LCA was conducted as per the framework and
the norms laid by the ISO 14040 series and the databases used was the
Ecoinvent 3.0, ( United States Environmental Protection Agency) USEPA
and the (Inventory of Carbon and Energy) ICE 1.6 from the~university of
BATH, United Kingdom. SimaPro 8.0 was used as the LCA tool for the
study.

\par\null

~

\subsection*{Life Cycle Impact
Assessment}

{\label{808567}}\par\null

Life Cycle Impact Assessment is carried out in 4 stages which are Goal
and Scope definition, Inventory Assessment, Impact Assessment

and

Interpretation.

\par\null\par\null

\selectlanguage{english}* Goal and Scope Definition: Defining the purpose of the study, system
and functional boundaries of the study.

\selectlanguage{english}* Inventory Analysis: Collection of all the input data related to energy
consumption, material usage etc.

\selectlanguage{english}* Impact Assessment: Quantification of~ Environmental impacts and input
resources.

\selectlanguage{english}* Interpretation: Interpreting the results calculated from assessment
stage and recommending suitable improvement measures.

\par\null

Before carrying out LCIA, it is necessary to define a functional unit.
The functional unit considered for this study is cubic meter. This study
was carried out for cradle to gate system boundary and it considered the
manufacturing of the construction materials and their transportation to
the construction site, on-site machinery, and electricity usage during
the construction phase of the building. The interpretation stage
consists of the following major steps: classification, characterization,
normalization, and weighing, of which procedure up-to characterization
stage is mandatory and normalization and weighing are optional, per the
ISO 14044. The impact of any product or a process is translated into
various impact categories. For LCIA, there are two possible approaches
for interpretation of results; the mid-point approach and the end-point
approach. The mid-point approach classifies impacts via impact
categories such as ozone layer depletion, global warming potential,
acidification and eutrophication potential which depicts a complete
picture of the impacts. The end-point approach distributes the impacts
into categories like damages to human systems, eco-systems and resource
depletion, which are easier to convey to the society. However, the
mid-point approach reveals more accurate and comprehensive results with
a lesser set of uncertainties than compared to end-point approach
{[}Curran MA. Encyclopaedia of ecology. Elsevier; 2008.{]}. Therefore,
mid-point approach for interpretation was used for the impact assessment
in this study.

\par\null\par\null

\par\null

\subsection*{\texorpdfstring{Life Cycle Carbon Emission Assessment
(LCCO\textsubscript{2}A)}{Life Cycle Carbon Emission Assessment (LCCO2A)}}

{\label{929388}}

During the construction process, there is

release

of carbon dioxide gas, methane, nitrogenous oxides and many other gases.
Carbon emission accounting quantifies the amount of carbon dioxide gas
released during the entire

life cycle

of the product i.e cradle to grave i.e for the initial phase,
construction phase, operational phase and the demolition
phase(\textbf{Figure 2} \textbf{system} \textbf{boundaries}). Carbon
accounting is a form of impact assessment which takes into account the
impacts of climate change due to the construction process. The carbon
impacts of the operational and the demolition phases are future impacts
and thus can only be projected. It becomes difficult to predict the GHG
emissions during the operational phase of the building as it depends
upon the amount of electricity and heating services used by the
residents, the frequency of repair and maintenance work for the building
and even the building architecture. Owing to this difficulty and to
avoid assumptions and discrepancies, the study mainly focuses on the
initial and the construction phase of the building.

\textbf{~}As per the (Intergovernmental Panel for Climate Change) IPCC
norms, carbon accounting is carried out by two methods, which are
top-down or

long term

approach and bottom-up or

short term

approach. The top-down approach consists of calculating the long life
emissions of the product i.e right up to the stage of demolition.
Top-down is approach is further classified as the Reference Approach and
Sectorial Approach. The

top down

approaches express the impacts to the economy or various economic
sectors rather than actual emissions at the plant. As

tis

approach estimates the long life impacts, it highly depends upon the
service life of the building, which in most cases for a residential
building is more than 50 years. Therefore, for a building during its
final stage of construction, it is difficult and involves assumptions to
estimate the carbon emissions for its service life.

~

The bottom-up approach consists of the calculation

for

short term

carbon emissions which are those occurring within twenty years of the
fuel use.

Bottom-up approach

takes into account the fuel consumption activities and estimates the
amount of carbon dioxide released. It can work effectively if reliable
databases are available or relevant data is obtained from the
enterprises which consume the fuels. The approach uses the schedule of
activities of fuel consuming equipment or the activity level directly
correlated with fuel consumption to quantify the carbon emissions. As
relevant databases and other datasets are available, the bottom-up
approach is used to carry out carbon accounting in this study.~

~~

The expression for carbon accounting is given as follows:

~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Carbon Account =
Q\emph{i} x EF~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~Equation (1)

~

where

Q

\emph{i}

:

Quantity of the construction material and EF: Emission Factor.

~

The amount of carbon dioxide released into the environment represents
the respective climate change that occurs. For any process, along with
carbon dioxide, there are many gases that are released like methane,
nitrogenous oxides like N2O, CFC-11 etc. The impacts of these different
gases will vary and hence there is a need to connect these various
impacts. Global Warming Potential (GWP) which translates the emissions
of a specific gas into its respective carbon dioxide equivalent was used
for this study.~ \textbf{The Intergovernmental Panel on Climate}

\textbf{Change (IPCC) has developed three sets of GWP to account for the
impact of a particular GHG with the same amount of CO2 under the
constraint of a set time horizon (TH). Therefore, GWP is the integral of
the global warming effect of GHG compared with that of CO2 in the same
time interval. Three TH are commonly calculated, namely 20 years, 100
years, and 500 years. IPCC's First Assessment Report (Tegart et al.
1990) quoted an atmospheric life-span of CO2 to be between 50 and 200
years. Therefore, it is common to use the IPCC 100 TH GWP. For methane,
the conversion coefficient is 25 and for nitrous oxide is 298.} Hence,
the amounts of methane and nitrogenous oxides released are then further
converted to equivalent kg CO2 by using GWP factor. The equation for the
conversion is given as follows:

~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Account = Q\emph{i} x
EF x GWP~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~Equation (2)

~

Therefore, the overall carbon emissions for any process or a product is
the net summation of carbon emissions from all the contributing elements
in the process. The final expression for carbon emissions is

~

Overall Account =

~=

~~~~~~~~~~~~~ ~~~~~~~~~Equation (3)

The study addresses various emission sources, classifying them as direct
and indirect emission sources to comprehensively depict the GHG
emissions associated with a construction process.

\par\null

\subsection*{Life Cycle Energy Assessment
(LCEA)}

{\label{107098}}\par\null

Life cycle energy analysis is an approach that quantifies all energy
inputs for a building over its entire

life cycle

\par\null\par\null\par\null

. The system boundaries for the energy analysis are illustrated in
figure 3. The system boundary comprises of manufacture, usage and
demolition phases for the building. The manufacturing phase comprises of
the production of the building materials, their transportation to the
construction site and energy consumption in the erection of the
building. The use phase of the building consists of all energy
requirements such as electricity, heating, air conditioning etc. It also
comprises of timely maintenance and repair works. Finally, the
demolition phase includes the destruction of the building and activities
related to the transportation of the materials to recycling plants or
landfills.

\par\null\par\null\par\null

Embodied energy is thus defined as the energy consumed during the
manufacturing of the building. It includes all the energy of the
building materials, energy consumption in the construction of the
building and also the energy used in maintenance and repairs. The energy
of building materials is the energy used in the extraction of raw
materials, manufacturing of the materials themselves and their
transportation to the construction site. Embodied energy is classified
into two types; the initial embodied energy and the recurring embodied
energy. Every building requires maintenance and undergoes repairs due to
several reasons. The recurring embodied energy is defined as the energy
inputs required for the maintenance and the repairs for any building
over its entire life. As the frequency of repairs and maintenance will
differ for every building, it is difficult to quantify the recurring
embodied energy (Er). The energy of the manufacturing phase is called
the initial embodied energy. It is given by the following equation:~

\par\null

Ei = Qi x EM Equation (4)

\par\null

where Qi: Quantity of the construction material and EM: Energy content
of the material per unit of its amount.

Energy consumption in the demolition phase of the building is called the
demolition embodied energy (DE). The energy consumed in the use phase is
called operational embodied energy (OE). Electricity usage, HVAC
(heating, ventilation, air conditioning), lighting are included under
operational embodied energy. This form of energy is highly dependent
upon the weather conditions, the behavior of the inhabitant and required
level of the comfort and thus is difficult to predict. Thus, the study
only evaluates the initial embodied energy for the building.

The summation of all the energies is called the life cycle energy for
the building. It is given by the following equation

\par\null

\section*{Case Study}

{\label{556467}}\par\null

\subsection*{Description of Project}

{\label{155653}}

The building chosen for the study is an

eight-storey

residential apartment building which is a part of the extension plan for
faculty and staff housing at the Hyderabad campus of BITS Pilani. Each
floor consists of two of each type of apartment, Type B, and Type C
respectively. The specifications of each apartment are presented in
Figure 1 and Figure 2. There are also service and main lifts. The entire
building was made up of Reinforced Cement Concrete (RCC) as the
load-bearing structural component and AAC blocks were used for masonry
work.

\par\null\par\null

\subsection*{Scope of the account}

The study covered the impacts for the cradle to gate boundary system for
environmental impact assessment, carbon accounting and energy accounting
for the building. It covered impacts arising from manufacturing of the
construction materials, their transportation to the construction site
and the machinery used for the erection of the building. It also
articulates the direct and indirect emissions of GHG arising from all of
these activities.

\par\null

\subsection*{Data Collection}

{\label{937964}}

To maintain the accuracy of the process data, the authors enlisted help
from the project manager, site engineers, and contractors. Further
details were extracted from the documents like the schedule of work,
bill of quantities, activity log, etc. Priority was allocated to
different sources based on the authenticity of the data. Table 1 depicts
the data source and the priority allocated to the respective data
sources.~

\par\null

\subsection*{Building Relevant Data}

{\label{858263}}

The quantities and specifications for the materials used for the
construction of this building were extracted from the BOQ obtained by
the project manager. Table 2 represents the materials used and their
respective quantities. The transportation distances for all the
materials have been selected after consulting with the projected
manager.

The machinery used during the construction process is also significantly
responsible for contributing to the CO\textsubscript{2} release. Various
types of machinery that are generally used during a construction process
are bulldozers, concrete mixers, concrete pumps, cranes etc. So, for
this study, a certain set of diesel operated machinery was selected
after consulting with the site engineer. Table 3 represents the
machinery used, their purpose and the machine capacity.

\section*{Quantification of the GHG
emissions}

{\label{662573}}

The quantification of the emissions occurring from the activities
occurring during the construction period () will be in accordance with
the ISO 14064 series, for both direct and indirect emissions. All the
emission factors related to the manufacturing of building materials and
transportation has been taken from the Ecoinvent 3.0 database and data
related to the machinery has been taken from IPCC 2006 and company
website.

\par\null

Majority of machinery or construction equipment run on fossil fuels like
diesel or petroleum and some on electricity. Naturally, they are bound
to emit various gases like carbon dioxide, xmethane, nitrogenous oxides,
(Chlorofluorocarbon) CFCs etc. The IPCC 2006 guidelines have suggested
emission factors for types of machinery running on diesel. The calorific
values and emission factors (or more correctly, the carbon content) of
fuels, being the intrinsic properties of fuels, depend from country to
country and location to location as the source of extraction of these
fuels varies.

Therefore, there arises a need for employment of correction factors to
closely relate the dataset suggested by IPCC guidelines to the

fuel

data of a respective country. Therefore for India, the net calorific
value for diesel is 10,800 kCal/kg or 45187 kJ/kg (1 kCal/kg = 4.184
kJ/kg) as per. Therefore, the correction as per (CHINA paper) is
depicted in the equations below:

\par\null\par\null

\par\null

Corrected emission factor = EF\textsubscript{IPCC} x Cdiesel Equation
(6)

where EFI\textsubscript{PCC}: Default emission factor from the IPCC
guidelines and Cdiesel: Net calorific value for diesel oil.

The default emission factors from the IPCC guidelines are 74100, 4.15,
and 28.6 kg/TJ for CO\textsubscript{2}, CH\textsubscript{4}, and
N\textsubscript{x}O respectively. As per equation 6, the corrected
values for diesel oil are as follows:

Corrected EFCO2 = 74100 kg CO2/TJdiesel x 45187
kJ/kg\textsubscript{diesel} x 10-9 = 3.35 kgCO2/kgdiesel

Corrected EFCH4 = 4.15 x 45187 x 10-9 = 3.35 kgCO2/
kg\textsubscript{diesel}

Corrected EFNxO = 28.6 x 45187 x 10-9 = 3.35
kgCO2/kg\textsubscript{diesel}

\textsubscript{}

As for the building materials, manufacturing of building materials are
the second largest contributors after the operational phase. Due to lack
of database in the Indian context, the quantification of GHG emissions
becomes difficult. Therefore, for this case study, the Ecoinvent 3.0
database was adopted for the emission factors. Although these factors
are developed in Switzerland, they still give an estimate as to which
parameters contribute more to the construction process. For the
transportation of the construction materials, the distances were assumed
as per the data are given by the project manager. Emission factors for
transportation were also taken from Ecoinvent database and were in terms
of (tonnes-km) tkm. As for the construction phase of the building, the
data for machinery used in the construction and their use schedules were
all obtained from the site engineer. The emissions from the machinery
usage were calculated as per the IPCC norms and methodology as described
earlier.

\section*{Results}

{\label{517719}}

\subsection*{Impact Assessment from
SimaPro}

{\label{813174}}\par\null

Impact assessment results for materials are relative to each other.
Figure 5 represents the impacts assessment results for two types of
masonry used Normal Fired Clay Brick and AutoClaved Aerated Block (AAC)
masonry. Fired clay brick are the ones that are most commonly used in
the construction sector. It is clear that fire clay bricks contribute
way more than the AAC blocks with respect to every impact category.
Their higher contribution implies that their production leads to more
emissions into the atmosphere (Global Warming and HH criteria
pollutants), into the air (Eutrophication and Smog) and requires more
energy input (Natural Resource Depletion). Figure 6 validates this
observation as CO2 emissions by fired clay brick are way higher than AAC
blocks. (Global warming is measured in terms of CO\textsubscript{2}
emissions).

\par\null

The life cycle assessment results for three concrete mixes, Conventional
concrete, concrete with fly ash and concrete with GGBS, are shown

is

Figure 7. As observed, concrete mix with GGBS contributes lowest to the
global warming potential but highest in eutrophication and smog
potentials. This can be accounted by the fact the GGBS handling and air
cooling

requires

resources which lead to these activities. Although GGBS contributes
positively with respect to ecological toxicity, its overall negative
impact supersedes it owing to its high contribution in eutrophication
and smog impact categories. Thus if only global warming potential is
being considered as the decision making parameter, GGBS is the optimal
choice. But if overall contributions are evaluated, fly ash is the
optimal choice, as its overall contribution is relatively lower with
respect to GGBS. Figure 8 validates this observation as GGBS concrete
mix is the lowest contributor

in

CO2 emissions.

\par\null

\par\null\par\null\par\null

After investigating for the most optimal concrete mix design, the
overall environmental impact of these concrete mixes in combination with
alternate masonries is to be evaluated. Life cycle studies are carried
for two cases: 1) Alternate concrete mixes using normal Fire Clay Brick
masonry and 2) Alternate concrete mixes using AAC masonry. Figure 9a and
9b represent the overall environmental impacts for all three
combinations for the building. For case 1, the approximate scores of
Conventional concrete, FA mix and GGBS mix with Clay Brick for global
warming are 120,115 and 110 respectively. For case 2, the scores for
Conventional concrete, Fly Ash mix and GGBS mix with AAC masonry for
global warming are 60, 55 and 25 respectively. Thus, the environmental
impact is significantly reduced if supplementary material like GGBS and
FA are used. But, as seen earlier, overall scores are needed to be
considered before making the decision. Hence, use of FA with AAC masonry
serves as the optimal choice.

\par\null\par\null\par\null

In reference to table 1, life cycle assessment for all the building
materials is carried out. For the all material inputs, three cases have
been considered. 1) Material inputs with conventional concrete and AAC
masonry, 2) Material inputs with Fly ash concrete mix and AAC masonry
and 3) Material inputs with GGBS concrete mix and AAC masonry. The
relative distribution of impacts of these cases is shown in Figures 10a,
10b, and 10c. For all three cases, Steel, Concrete, Italian Marble, and
AAC masonry are found to make the most significant contribution to all
impact categories followed by granite flooring and paint. For other
materials like sand and Kota stone, the impact is relatively negligible.
For global warming impact category, case 1 has the highest score
followed by case 2 and case 3. Therefore, if only global warming is to
be addressed, case 3 is the optimum choice.

In reference to table 1, life cycle assessment for all the building
materials is carried out. For the all material inputs, three cases have
been considered. 1) Material inputs with conventional concrete and AAC
masonry, 2) Material inputs with Fly ash concrete mix and AAC masonry
and 3) Material inputs with GGBS concrete mix and AAC masonry. The
relative distribution of impacts of these cases is shown in Figures 10a,
10b, and 10c. For all three cases, Steel, Concrete, Italian Marble, and
AAC masonry are found to make the most significant contribution to all
impact categories followed by granite flooring and paint. For other
materials like sand and Kota stone, the impact is relatively negligible.
For global warming impact category, case 1 has the highest score
followed by case 2 and case 3. Therefore, if only global warming is to
be addressed, case 3 is the optimum choice.

\par\null

\subsection*{Carbon Accounting}

{\label{463250}}\par\null

\subsubsection*{Indirect emissions - For manufacturing of construction
materials}

{\label{936942}}\par\null

Using the mentioned data for the building, databases, and equations, the
net GHG emissions have been calculated. Figure 2 shows indirect GHG
emissions. The contribution of each building material towards CO2
generation is shown in Figure 11. The total CO2 emissions in figure 11
are 1030.742 tonnes. Concrete leads the contribution followed by steel
and AAC masonry. Construction materials like paint and safety grill
contribute relatively less as compared to the other materials. For
steel, the main component in steel manufacture is coking coal. When coal
is burnt at high temperatures or carbonized in an oven until it becomes
coke. This coke is then cooled and used in the blast furnace. Coking
coal contributed up to 50\% of the energy sources used for the
production of steel followed by electricity (35\%). Obtaining of coke
from coal releases high amounts of carbon dioxide and other air
emissions like naphthalene, coke dust, and sulfur. For concrete, cement
manufacturing process is the leading cause of CO\textsubscript{2}
release to the environment. In the cement production process, the
clinker burning process is the leading cause of environmental emissions
and energy drainage. For every mole of clinker produced the balance is
emitted to the air in the form of CO\textsubscript{2} waste. The
reaction is as follows:

\par\null

For various alternate masonry considered, the emissions arising from the
masonry alternative utilized for the same building are shown in table 5.
Conventional fired clay brick masonry has the highest emissions while
sand lime masonry has the lowest.

Table 6 represents the amount of methane and nitrogenous oxides released
in the manufacturing of the construction materials. Calculated as per
the aforementioned methodology, table 6 represents the CO2 equivalents
for methane and nitrogenous oxides. Therefore, the total CO2 releases to
the environment due to the manufacturing of building materials is
18629.021 tonnes.

\par\null

\subsubsection*{Indirect emissions - Carbon accounting for the
transportation of Construction
Materials~}

{\label{371033}}

The amount of releases to the environment also depends upon the
distances from which the construction materials are obtained. Table 7
represents the assumed the type of vehicle used in the transportation of
various construction materials.

\par\null

The distances from where the construction materials are transported play
an important role, both environmentally as well as economically. Figure
11 represents the contribution of emissions from transportation of
various materials. The amount of CO2 released during transportation is
127.67 tonnes. Transportation vehicle capacity and its efficiency, the
distance of the construction site form the manufacturing plant and the
amount of material are factors affecting the CO2 emissions. Concrete,
with 4876.8 tonnes of CO2, leads the contribution it is required in the
highest amount during construction.

As per equation 1 and 2, Table 8 represents the total methane and
nitrogenous oxides released during the transportation of building
materials and also the respective net CO2 equivalents. The total
CO\textsubscript{2} emissions during the transportation of construction
materials is 190.861 tonnes.

Therefore, the net emissions arising from the indirect emission sources;
manufacturing of building materials and transportation of building
materials is 18819.882 tonnes. The manufacturing of building materials
contributes dominatingly with 98.9\% of the total indirect emissions.
Therefore, selecting alternate building materials with lower carbon
content and selecting nearby product suppliers can be regarded as an
effective strategy to reduce the emissions. Also, it is required to
compare these results with other available literature.

\par\null

\subsubsection*{Direct emissions - Carbon accounting for the on-site
construction machinery
used}

{\label{353370}}

The machinery used during the construction process is also significantly
responsible for contributing in the CO2 release. Various types of
machinery that are generally used during a construction process are
bulldozers, concrete mixers, concrete pumps, cranes etc. So, for this
study, a certain set of diesel operated machinery was assumed. Table 9
represents the machinery used, their purpose and the machine capacity.

Table 10 represents the total CO2, CH4 and NxO emissions arising due to
the usage of the diesel operated equipment. It also represents the net
total equivalent emissions, calculated as per the methodology described
earlier, arising due to the on-site machinery used.

Therefore, the total CO2 emissions accounting for the direct emissions
is 3485.01 tonnes. Thus, use of machinery and equipment in the erection
of a building contribute significantly higher than the transportation of
building materials.

\par\null

\subsubsection*{Carbon accounting using alternate
database}

{\label{910606}}\par\null

One of the drawbacks bottom-up or shot term carbon accounting approach
is that it is dependent on the database used for extracting the emission
factors. A database developed in a particular country if from the
information available for that country. For example, the manufacturing
of steel in London will be different than that in Hyderabad, as the
source of raw materials is different, the technology used is different
and the fossil fuels used are from different sources. Therefore, the net
carbon dioxide generated in the production of 1 ton of steel in London
will be different than that for the 1 ton of steel produced in India.
Similarly, for other construction materials, the values of these factors
vary.

Thus, to study the impact of the change in the database on the
emissions, alternate databases were used. Therefore in this study, the
(Inventory of carbon and energy) ICE 1.6 database published by
University of BATH (United Kingdom) has been used as an alternate
database to the Ecoinvent 3.0 (European) database. As the methodology
for calculating the carbon emissions remains the same, i.e the bottom-up
approach, the same equations can be used again. Therefore, following the
same set of IPCC norms (equation 1 and 2) and using the ICE 1.6
database, the total CO2 emission for the manufacturing of construction
materials was calculated to be 1423.67 tonnes. The percentage change
with respect to the CO2 emissions from the Ecoinvent database was found
out to be 27\%.

As a change in the database impacts the emissions from manufacturing of
construction materials, the similar impact is observed for the vehicles
used for transportation. For the transportation of building materials,
the alternate database that was used in the study was the USEPA (United
States Environment Protection Agency) database. Keeping the bottom-up
approach constant and following the IPCC norms, the total CO2 emissions
resulting from the transportation of building materials is 139.9 tonnes.
The percentage change with respect to the CO\textsubscript{2} emissions
from the Ecoinvent database was found to be 27\%.~

\subsection*{}

\subsection*{Energy Account}

{\label{867612}}

By applying corresponding emission factors from the ICE 1.6 database and
using the bottom-up approach, the embodied energies for the building
materials have been calculated. Figure 13 represents the contribution of
various construction materials to the embodied energy. The total energy
content of building materials is 15.65 TJ.~~~~

\par\null

Steel and concrete lead the contribution as the number of energy sources
required for their production are quite high. Production of clinker in
cement manufacturing is the leading cause of high energies of concrete.
Clinker production requires energy from petroleum and as high amounts of
concrete are required for any building, concrete production leads to
high energy consumption. In case of steel production, coal is required
for producing coke. In the production of steel, this coking coal
contributes more than 50\% energy-wise. Therefore, burning of coal for
the production of steel accounts for higher amounts of energy. Masonry
(the type of masonry used in the building) follows after steel and
concrete. As in the actual building construction, AAC masonry has been
used instead of conventional brick masonry. The masonry is then followed
by paint and marble usage as they show a significant amount of energy
content. In case of sand (3\%) and rubble (1\%), the embodied energy is
close to negligible. This is because, it was assumed that no process was
used to extract sand and rubble, for example, blasting of rocks for
rubble and only for their transportation resources were utilized.
Although the embodied energy content for aluminum per kg is more than
that for steel, the quantity of aluminum that was used in this building
(as per Bill of Quantities) was comparatively lesser than the steel
quantity. Therefore, the contribution of steel is significantly higher.
Therefore, it is imperative to choose materials with lesser energy
content. One of the leading contributors in terms of energy is steel.
However, steel is one of those materials which, currently does not have
a viable alternate substitute with lesser energy content which even
satisfies in terms of engineering properties like structural strength.
Hence, the steel type used for construction is unlikely to be changed.
Building materials like concrete and masonry are also materials
contributing heavily in terms of life cycle energy emissions. But unlike
steel, alternate concrete mixes and masonry are available which even
satisfy the structural requirements with respect to a conventional
concrete mixture. Hence, concrete and masonry are the two building
materials where lower energy content substitutes can be employed to
reduce the energy content of a building. Therefore, using alternate
concrete mixes and masonry can serve as an energy efficient strategy.

\section*{Discussions}

{\label{852882}}\par\null

To sum up, out of all the building materials used for construction,
production of steel, concrete, and masonry leads to higher environmental
implications with respect to the production of other building materials.
Thus these three form the platform to implement alternative and greener
substitutes, in order to bring down the overall environmental impacts.
The AAC masonry had a lower environmental impact score with respect to
conventional brick masonry. Using AAC masonry instead of conventional
brick masonry would significantly reduce the environmental impact score
for the building. As seen, using alternate concrete mixes like a
concrete mix with fly ash and concrete mix with GGBS significantly
reduce the environmental impacts. Therefore, implementing alternate
concrete mixes and alternate masonry would ultimately reduce the overall
life cycle impact of the building.

Further, the building material production cause for a comparatively
higher amount of net CO2 release than their transportation to the site
and even than the construction equipment used for the erection of the
building. Production of building materials like cement and steel
involves a large amount of fossil fuel energy use and as they are the
primary construction materials used in any building, their energy and
carbon content has a high impact on the life cycle properties of the
building. As a result, using materials with lower carbon content would
significantly reduce the GHG emission arising from these construction
materials. Also, in this study, the impact of usage of construction
equipment like a concrete mixer and concrete pumps was also studied.
Concrete mixers and pumps are widely used at the majority of
construction sites in India and hence, quantifying GHG emissions arising
from them is of extreme importance. It is seen that GHG emissions
resulting from them are even more than those from the transportation of
construction materials. Therefore, careful utilization of these types of
equipment is necessary as they add to the life cycle emissions of a
building which can be done by implementation of appropriate construction
management strategies.

Also, the production of building materials involves extraction of raw
materials, for example, extraction of iron from iron ore for steel
production. These extraction processes are carried out by using the
energy generated by the burning of fossil fuels. As seen, production of
building materials possesses high energy content. Therefore, the
material choices that are made for a building determine the energy
content of the building. Smart and effective choices in selecting
construction materials are thus required to bring down the energy
consumption. As for any building, there is not much that can be done to
bring down the energy consumption and GHG emissions, once the
operational or the use phase begins. Therefore, choosing greener
materials for construction is imperative which can be only done at the
start of the project or during the design phase of the building.

~

The study encompassed the assessment of life cycle impact for a
building, the GHG emissions associated with the building and the
embodied energy consumption for the residential eight-storey building.
Throughout the entire process of this study, there were various problems
identified that are needed to be addressed to improve further research.
Firstly, the data relevant to the building were extracted from the bill
of quantities. However, some of the data had to be estimated based on
the building drawings and plans. Due to confidentiality of the
construction firm, there were difficulties in collecting the data and in
some cases had to be assumed. Due to unavailability of accurate data
like the distance of transportation of construction materials, they had
to be assumed. Working hours of machinery and their schedules were
obtained from the bills and site engineer (Data priority table).
Secondly, due to unavailability of the database in the Indian context,
the material characteristics in the foreign database were thoroughly
examined and were then chosen to represent the equivalent material in
the Indian context. Therefore, there is a need to develop a database for
India, in order to accurately carry out life cycles studies. Due to
unavailability of datasets, confidentiality of firms and reluctance from
contractors to give details pertaining to site leads to various
assumptions and these assumptions lead to uncertainties in the life
cycle study.

~

\section*{Conclusion}

{\label{831865}}

This study evaluated three major sub-categories of life cycle studies
which are Life cycle Impact Assessment (LCIA), Life cycle energy
assessment (LCEA), and Life cycle carbon emission assessment (LCCO2A).
As construction sector is one of the largest contributors in energy
consumption, it has led to several consequences like heavy emissions of
GHG in the environment. Hence, a lot of scientists and researchers are
now focusing on quantifying these emissions and impacts and are trying
to bring them down. This study was carried out under the ISO 14064
guidance to evaluate the environmental impacts, the GHG emissions and
the embodied energy for an eight-storey residential building in India.

For LCIA, the impact of various construction materials for the building
were calculated using SimaPro 8.4 as an LCA tool. Use of AAC masonry
instead of normally fired brick clay reduced the environmental impact
significantly. Although sand-lime bricks have the lowest impacts than
other alternatives, they are not used as they fail to satisfy structural
requirements. As fired clay brick are denser than AAC blocks, for the
given volume, their impact is much higher. If global warming was the
main decision-making parameter, the most suited concrete mix was GGBS
mix and the most suited masonry was AAC bricks. But, if the overall
contributions to all the impact categories are considered, the mix with
fly ash proved to be the most suitable option as GGBS production
contributed heavily in eutrophication. Materials like steel, concrete,
AAC masonry and Italian marble had most significant impacts on the
building followed by paint and granite.

\par\null

For LCCO\textsubscript{2}A, the production of the building materials
results in the release of various GHGs in the environment which affects
the climate by causing global warming. In this study, the GHG emissions
during production of various building materials were evaluated and it
was found that concrete, steel, and masonry were the highest
contributors. It was found that conventional fired clay brick was ranked
highest in terms of net CO\textsubscript{2} emissions and AAC masonry
was ranked third. It was also found that production of building
materials contributed 98.9\% to the indirect emissions arising from a
building construction. Also, the machinery and equipment used in the
erection of the construction site contributed more than that by the
transportation of building materials. Implementing alternate
technologies and employing greener materials for concrete and masonry
would reduce the overall carbon dioxide emissions. Therefore, smartly
using construction management tactics and wise usage of machinery would
help reduce the life cycle emissions for a building. It was also found
that there was a 27\% difference for CO\textsubscript{2} emissions when
the database was changed from Ecoinvent to ICE 1.6. This reveals that
quantification of CO2 emissions highly depends on the dataset utilized.
Hence, with respect to the Indian context, it is necessary to develop a
dataset which would give a more accurate picture of life cycle emission
for a building.

~

LCEA, for any building, is the energy content for that building. It
helps in determining the parameters involved in the process which
possess largest energy content i.e the parameters whose production
involves highest energy consumption. For this study, it was found the
concrete and steel are the construction materials which have the highest
energy content. Therefore, alternate concrete mixes which possess
greener materials like fly ash can be utilized to reduce the overall
energy content of the building. Also, among the various types of
masonry, conventional brick masonry possessed the highest energy content
with 11878.75 MJ and AAC ranked fourth with embodied energy as 2966.7
MJ. Therefore, if AAC masonry were to be used, it would save up to 75\%
of the energy consumption i.e 75\% decline in the usage of fossil fuels.

To summarize, this study only evaluated the manufacturing phase and the
construction phase. Although the results have been obtained using
Ecoinvent database, a foreign database, the study still gives an idea
about which are the parameters that are responsible for the impacts.
Thus, if these parameters are known, changes can be implemented and thus
the overall impact and emissions and energy consumption can thus be
reduced. Therefore, LCA can be used as a decision-making tool in
selecting appropriate construction materials and practices. Use of
recyclable materials can be beneficial as they save on energy
consumptions and CO2 emissions both. Hence, the choice of materials and
their sources should be given proper importance during the design phase
of the building itself. Wisely choosing the construction materials and
obtaining materials from nearby sources rather than far away distances
will help in reducing the impact significantly.



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\textbf{}

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\subsection*{}

{\label{155653}}

\subsection*{}

{\label{155653}}\par\null

\subsection*{}

{\label{100064}}\par\null

\subsection*{}

{\label{155653}}





\par\null

\section*{Acknowledgements}

{\label{687807}}

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a elit at fringilla. Lorem ipsum dolor sit amet, consectetur adipiscing
elit. Nulla congue consequat consectetur. Duis ac mi ultricies, mollis
ipsum nec, porta est.

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