TOWARDS SUSTAINABLE CONSTRUCTION IN DELHI:
STRATEGIES TO REDUCE CARBON FOOTPRINT IN
DOMESTIC BUILDINGS
INTRODUCTION
Natural resources are heavily used by the construction sector. Energy use and CO2 emissions are mostly
driven by activities associated to construction. Embodied energy (EE), which is used to describe the energy
used in the production and transportation of building materials and components, is used both in the preoccupation state and during occupancy, when appliances are used and the structure is inhabited. About 22%
of the CO2 emissions caused by the Indian economy are produced by the construction industry. 80 percent
of emissions from the construction industry are mostly attributable to the manufacturing of energy-intensive
building materials such cement, lime, steel, bricks, and aluminium [1]. Furthermore, choices made at every
step of the design process have an impact on the constructed form's sustainability. The shape and scale of
the built form, orientation, site planning, design of building components like roofs, walls, apertures (doors
and windows), and design of building features like windows and shading devices are all included in the
design of built form using solar passive approaches [2]. A sustainable building approach should ideally take
into account all the factors that lower energy use and carbon emissions into the atmosphere. A building's
level of sustainability is assessed by contrasting it with a comparable building. Building attributes may be
used to develop comparison standards. These reference building benchmarks' development necessitates
various presumptions and data gathering. While some factors, such as activity, occupancy data, building
area, number of pupils, and building age, can be easily gathered through questionnaires, other crucial
information for evaluating the energy performance of the building, such as construction details and type and
efficiency of heating systems, must be gathered from all stakeholders involved in the planning and designing
stage of the building [3].
This study presents a plan for sustainable building that considers soil, resources, material, and water
conservation. It promotes the wise use of non-renewable resources while increasing the use of renewable
resources, reducing waste production, eliminating waste, using equipment and materials more effectively,
and managing consumption via customs regulations. Each attribute has an impact on the building's overall
sustainability. Building development and environmental performance are site-specific. The environmental
performance of a building is improved by proper management at all stages of building development,
including construction, fitment, outdoor facility construction, transportation, operation, waste treatment,
property management, demolition, and disposal, with related material, equipment, energy, and manpower
inputs [4].
Fig 1. Breathe Clean City
Building a new structure using a sustainability strategy is fairly simple. This is so that all activities may be
controlled more readily in modern structures than in older ones. Building construction resource usage is
often reduced by quantification and comparison. Energy labelling systems for buildings are useful here. The
Building Research Establishment's Environmental Assessment Method (BREEAM), the GB Tool, LEED
(Leadership in Energy and Environmental Design), CASBEE (Comprehensive Assessment System for
Building Environmental Efficiency), Green Globes, and GRIHA (Green Rating for Integrated Habitat
Assessment) are just a few of the voluntary energy labelling systems that are widely used around the world
[5]. A voluntary building evaluation programme encourages owners to make greater efforts to reduce their
energy use [6]. Studies that have been done to enhance the environmental performance of buildings point
to the creation of policies, evaluation and monitoring, life cycle analysis and simulation, and the choi ce of
building materials as key regulating elements [7]. The attitude of authorities [8–11], the nation's economy
[12–13], the accessibility of local energy sources [14–16], the level of technology [15–17], and consumer
behaviour [18–19] have been recognised as key elements in the plan to enhance the overall performance of
buildings.
In its most basic form, a sustainable building is both water and energy efficient. The majority of sustainable
construction techniques take into consideration energy conservation depending on the building's occupancy
status. Some studies indicate that up to 40% of the life-cycle energy demand in residential buildings comes
from the embodied energy of such structures. A structure's initial embodied energy is the energy needed to
create it, while its recurrent embodied energy is the energy necessary to maintain and repair the building
over the course of its useful life. [20]. System boundaries, EE analysis techniques, geographic study area
location, primary and delivered energy, data source age, source of data, completeness of data, manufacturing
process technology, consideration of feedstock energy, and temporal representativeness are the ten
parameters that determine the quality of EE data. [21]. One of the key parameters considered in the current
research is the embodied energy of the construction materials.
Fig 2. The Carbon Footprint
Potable water becomes scarce as a consequence of unchecked ground water resource extraction. Harvesting
rainwater is an appropriate solution in this case. Although there is a significant upfront expense associated
with this technology, it ultimately proves to be cost-effective. The materials utilised, the design and
construction, the maintenance, and the overall quantity of rainfall all affect how well rainwater is collected.
Clay tiles often collect less than 50% depending on the harvesting technique, compared to cement tiles,
which have a year-round roof runoff coefficient of roughly 75%. With an efficiency of between 80 and 90
percent, plastic and metal sheets perform well [22]. Combining different water management strategies may
reduce water use by up to 50%, relieving strain on the planet's finite water supplies. The fact that the water
is recycled for various purposes makes it possible to accomplish this decrease while using less fresh
groundwater.
Similar steps may be taken to decrease both environmental and monetary effects. For example, installin g
low-flow showerheads can cut the yearly environmental impact of indoor water usage by 8%, while
installing rainwater collecting systems can cut it by up to 38%. These solutions, such as faucet aerators,
low-flow showerheads, and dual flush toilets, are profitable over the long run [23].
Similar to this, operational energy services such as heating, ventilation, and air conditioning (HVAC),
lighting, equipment, and appliances contribute to around 80% of the overall energy consumption of a
building during its lifetime [24]. Carbon emissions are decreased when building exterior thermal efficiency
improves. A reduction in carbon emissions of between 31 and 36 percent may be achieved by retrofitting,
rebuilding, and the use of suitable U-factors for building materials. Combustion energy regeneration, reuse,
and recycling combined may reduce emissions and overall energy usage by up to 10% [25].
However, the pattern of energy use in residential applications varies geographically with tenant behaviour.
Various labelling and grading systems are examined in order to establish the sustainable construction plan
for the residential structure in the composite climate. Different factors connected to environmentally
friendly building methods are found. The data is gathered via field research. The sustainable building plan
that has been devised is used. The suggested sustainable construction strategy's economic feasibility for the
case study of the residential building under consideration is calculated on a yearly basis.
Concept of carbon footprint
The term "carbon footprint" has its roots in the term "ecological footprint," which was first used by Wacker
Nagel and Rees (1996). The term "ecological foot-print" refers to the total number of hectares of biologically
productive land and water needed to support a certain human population. This idea states that the term
"carbon footprint" refers to the amount of land needed to absorb all of the CO2 created by humanity
throughout the course of its existence. Use of the carbon footprint spread throughout time as the subject of
global warming gained importance on the environmental agenda, although in modified form (East 2008).
Since many years ago, the idea of "carbon footprinting" has been in use, although it is also referred to as
"life cycle impact category indicator global warming potential" (Finkbeiner 2009). As a result, the current
version of the carbon footprint may be seen as a hybrid, taking its name from the phrase "ecological
footprint" and theoretically serving as a possible indication of global warming. Despite the current nexus
around it, there are few studies that measure carbon footprint in terms of world hectares (Browne et al.
2009).
In addition to its widespread positive public perception as a measure of an entity's contribution to global
warming, there are misunderstandings about what it really implies (Wiedemann and Minx 2007;East2008;
Finkbeiner2009; Peters 2010). Additionally, it is noted that there is a dearth of scientific literature on the
topic, and the majority of research have been conducted by private groups and businesses primarily because
of their financial acumen rather than their environmental duty (Kleiner 2007; Wiedemann Minx
2007;East2008). Embodied carbon, carbon content, embedded carbon, carbon fluxes, virtual carbon, GHG
footprint, and climate footprint are other terminology that are often used interchangeably with or as
synonyms for carbon footprint in the literature that is currently accessible (Wiedemann and Minx 2007;
Courchesne and Allan 2008; Edgar and Peters 2009; Peters2010).
The definitions of carbon footprint in the literature and research that are currently accessible are not
consistently used (Wiedemann and Minx 2007). Wiedemann and Minx (2007) defined the carbon footprint
as a measure of the exclusive total quantity of carbon dioxide emissions that are created by a certain activity
or are accumulated throughout the course of a product's life phases. This definition is based on their survey.
As a complete GHG indicator, or if all the GHGs coming from inside the border are measured, a new phrase
called "climate footprint" has been suggested. The Office of Sustainability and Environment, City of Seattle,
2002; Kelly et al. 2009; Eshel and Martin 2006; Bokowski et al. 2007; Ferris et al. 2007; T C Chan Center
for Building Simulation& Energy Studies/Penn Praxis 2007; Garg and Dornfeld 2008; Good Company
2008; Johnson2008; Edgar and Peters 2009; Browne et al. 2009; Kelly et al. 2009; Eshel and Martin 2008;
Bokowski et.
Fig 3. The Carbon Footprint of a Building
The choice between direct and embedded emissions is not consistently applied. Direct emissions are those
produced immediately as a process moves forward. As an example, a direct emission is CO2 that is released
during combustion in an industrial boiler that burns gasoline. On the other hand, no direct emissions will be
seen in a boiler that is heated by electricity. The quantity of CO2 emitted during the production and
transmission of the units of energy used in the boiler, however, is known as the embodied or indirect
emission if it came from a thermal power plant where the boiler's electricity was produced. Since it becomes
difficult to account for all potential emissions, most studies simply provide direct or first order in direct
emissions (Carbon Trust 2007b; Wiedemann and Minx 2007; Matthews et al. 2008b). Due to the lack of
consistency in the gases used and the limits set for the carbon footprint estimates, the results from various
organisations' computations vary greatly (Wiedemann and Minx 2007; Kenny and Gray 2008; Padgett et al.
2008). Consistent carbon footprint assessments are necessary to enable comparisons since they are linked
to financial transactions that reveal taxes, carbon offsets, or changes in consumer preferences. The
CO2equivalent (CO2-e) mass based on 100 years of projected global warming has been adopted as the
reporting unit for carbon footprint despite ongoing variations in computations (WRI/WBCSD 2004; Carbon
Trust 2007b; BSI 2008). "Footprints are geographical indicators," according to Hammond (2007) and the
Global Footprint Network (2007). As a result, the phrase "carbon footprint" should really be termed "carbon
weight" or "carbon mass" (Jarvis 2007). But since it is easy to calculate and has widespread acceptability,
CO2-e mass has been advocated as the measure of carbon footprint (Lynas 2007). A person, company,
process, product, or event's carbon footprint is therefore defined as the amount of GHGs stated in units of
CO2-e that are released into the atmosphere from inside a predetermined boundary. According to the
approach used and the goal of carbon foot printing, which is covered later in this review, the set of GHGs
and limits are established.
Importance of carbon foot printing
Being a quantifiable representation of GHG emissions from an activity, the carbon footprint aids in
managing emissions and evaluating mitigation strategies (Carbon Trust 2007b). After the emissions have
been quantified, the significant sources of emissions may be identified, and areas for emission reductions
and efficiency improvements can be targeted. Cost savings and environmental efficiency are made possible
by this. It is necessary to report one's carbon footprint to a third party or disclose it to the public i n order to
comply with legal obligations, engage in carbon trading, practise corporate social responsibility, or enhance
a brand's reputation (Carbon Trust 2007b;L.E.K. Consulting LLP 2007).
Fig 4. Effects of Carbon foot printing
Cities and organisations' carbon footprints have been measured and reduced via legislative measures, and
this information is crucial for formulating policy (Office of sustainability and environment, City of Seattle
2002; Courchesne and Allan 2008;Good Company 2008). According to the "Consolidated Appropriations
Act, 2008," the USA has made it necessary to maintain a record of emissions from businesses (Rich 2008).
The EU has also taken the initiative in developing regulatory requirements for reducing emissions associated
with aviation. California set a ceiling on GHG emissions from large enterprises and prohibited the import
of non-conventional fuels for vehicles unless they had a lower carbon footprint than gasoline produced from
petroleum (Courchene and Allan 2008). The California Global Warming Solution Act of 2006 seeks to
reduce emissions in California to 1990 levels by the year 2020. (Capoor and Ambrosi 2009). The UK
Government encourages families to help create a low-carbon future via the Low Carbon Transition Plan,
2009. (Department of Energy and Climate Change 2010). Most businesses and virtually all individuals have
been seen to work toward lowering emissions or offsetting footprints via the purchase of carbon credits or
other control methods. In addition to legislative considerations, carbon footprint is very significant for
business.
The business sector has seen that the economy will soon be carbon-constrained (Kleiner2007). Therefore,
there is a global rush to measure carbon footprints and reduce emissions in order to gain a competitive edge
(Kleiner 2007). In a survey conducted by L.E.K. Consulting LLP(2007), it was discovered that 44% of
consumers preferred to buy the products, which provided the information about their carbon footprints,
while 43% were willing to pay more for the products with relatively low carbon footprint. This is
demonstrated by the fact that number of companies participating in CDP increased from 383 in 2008 to 409
in 2009 (CDP 2009). As a result, the business sector has made a significant response.
As people become more aware of climate change, there is a discernible increase in their anxiety over their
personal responsibility for GHG emissions. Due to this, there has been an increase in personal carbon
footprint measurement tools (consultancies and online calculators), especially in industrialised nations
(Padgett et al. 2008; Kenny and Gray2008). After calculating the footprint, they offer to offset it by planting
trees, supporting forestry, and using renewable energy sources (Murray and Day 2009), and as a result, since
1989, there has been a significant increase in the market for voluntary carbon emissions (Hamilton et al.
2007). Individuals' tendency to walk and ride bicycles may be changed to reduce the need of fossil -fueled
transportation systems (Franket al. 2010). In addition to its significance for business, the carbon footprint
has been utilised as a gauge for how a citizen's lifestyle affects a nation's carbon emissions. A useful tool
for comparing the contributions of nations, cities, and sectors to global warming is the country-wise per
capita carbon footprint, which was released by the UNDP (2007) and Edgar and Peters (2009).
It is obvious that high affluent nations leave the largest environmental footprint, whilst underdeveloped
countries' footprints are much less. These days, an essential event management metric is the carbon footprint
(London 2012 Sustainability Plan 2007). Studies on the quantitative effects of natural and semi -natural
systems on carbon footprint are presented (Chambers et al. 2007). Comparing the effects of human and
natural factors on the environment might be useful. As a result, it is clear that almost no entity is immune
from carbon footprinting.
Calculation of carbon footprint
The quantity of GHGs released, withdrawn, or embodied over the life cycle of the product must be calculated
and summed in order to calculate carbon footprint. The term "life cycle" refers to the whole process of creating
a product, from the procurement of raw materials through final packaging, distribution, consumption, and
usage, to the last steps of disposal. Cradle to grave analyses are another name for life cycle analysis. With
regard to the production of air pollutants, water usage and wastewater generation, energy consumption, GHG
emissions, or any other comparable parameter of interest and cost-benefit measures, life cycle assessment
(LCA) generates a full picture of inputs and outputs. This analysis is often referred to as an environmental
LCA. LCA, also known as GHG accounting, calculates the GHGs released or embodied at each recognised
stage of the product's life cycle for the goal of calculating carbon footprints. For GHG accounting, standards
and guidelines are provided. Typical resources include:
1. GHG protocol of World Resource Institute (WRI)/World Business Council on Sustainable
Development (WBCSD): A Product Life Cycle Accounting and Reporting Standard and Corporate
Accounting and Reporting Standard: Guidelines for Value Chain (Tier III) Accounting and Reporting
are the two standards. It deals with quantifying GHG reductions brought about by the implementation
of mitigation techniques in its Project protocol and offers sector-specific and general calculation tools.
It serves as the foundation for the majority of GHG accounting regulations, such as ISO 14064 (parts
1 and 2) (WRI/WBCSD 2004, 2005).
2. ISO 14064 (parts 1 and 2): It is an international standard for setting limits, calculating emissions of
greenhouse gases, and removing them. Additionally, it offers guidelines for creating GHG reduction
programmes (ISO 2006a,b).
3. Publicly Available Specifications-2050 (PAS 2050) of British Standard Institution (BSI): It details
how to measure the life cycle GHG emissions of products and services (BSI 2008).
4. 2006 IPCC guidelines for National Green house Gas inventories: Four categories—energy, industrial
process and product usage, agricultural, forestry and other land use, and waste—are used to group all
anthropogenic sources of GHG emissions. The older 1996 criteria have been amended in the 2006
recommendations. Following these guidelines, all UNFCCC signatory nations are required to create,
maintain, and share national inventories of their GHG emissions and removal. As a result, the nations'
emission and removal inventories are similar. However, the UNFCCC has not yet made using the 2006
criteria mandatory, thus the majority of countries continue to utilise the 1996 rules.
5. ISO 14025: It is a guideline for doing LCA.
6. ISO 14067: A standard for measuring a product's carbon footprint is being created.
Some nations, such the Department of Food and Rural Affairs (DEFRA) and Carbon Trust in the United
Kingdom and the Environmental Protection Agency (EPA) in the United States, have created their own GHG
accounting standards. Based on these principles, registries and consultancies like World Wildlife Fund
Climate Servers, California Climate Registry, The Climate Registry, etc. have developed their own techniques.
Nearly all of these recently created guidelines and standards require what is known as comprehensive LCA,
which is accounting for the GHGs released throughout the creation, use, and disposal of the product, entity,
or event.
LITERATURE REVIEW
In June 2007, a search of all scientific journals and all search topics covered by Scopus1 and ScienceDirect2
for the phrase "carbon footprint" (i.e., when these two terms are placed next to each other in this sequence)
produced 42 results; 3 from the year 2005, 8 from 2006, and 31 from 2007. The majority of articles address
the issue of how much carbon dioxide emissions may be connected to a certain product, business, or institution,
but none of them provide a clear explanation of the phrase "carbon footprint." Typically, the term "carbon
footprint" refers to emissions of greenhouse gases or carbon dioxide represented in CO2 equivalents.
For a great overview of current research on input-output analysis and the carbon footprint, go here (Minx et.
al., 2007). The majority of research are for rich countries even though our special concentration is on India
and underdeveloped nations because of the availability of data.
Grey literature definitions of "carbon footprint" BP (2007) The quantity of carbon dioxide released as a result
of your everyday actions, such as doing a load of laundry or transporting a busload of children to school, is
known as your "carbon footprint."
Sky Broadcasting (British) (Patel 2006) By "measuring the CO2 equivalent emissions from its premises,
company-owned cars, business trips, and garbage to disposal," the carbon footprint was determined.
"A technique to assess the total emission of greenhouse gases (GHG) in carbon equivalents from a product
over its life cycle, from production of the raw materials utilised in its manufacturing to disposal of the final
product," according to Carbon Trust (2007) (excluding in-use emissions).
"... a method for detecting and quantifying the specific greenhouse gas emissions from each activity inside a
supply chain process step and the framework for attributing them to each output product would refer to this as
the product's "carbon footprint"). (2007) Carbon Trust
The whole level of direct and indirect CO2 emissions brought on by your company operations, according to
Energetics (2007).
The "Carbon Footprint" is a measurement of the effect human activities have on the environment based on the
quantity of greenhouse gases created, measured in tonnes of carbon dioxide, according to ETAP (2007).
"The demand on biocapacity necessary to absorb (through photosynthesis) the carbon dioxide emissions from
fossil fuel burning," according to Global Footprint Network (2007). (GFN, 2007)
(2007) Grub & Ellis "The quantity of carbon dioxide released into the atmosphere as a result of using fossil
fuels is measured as a carbon footprint. In the context of a business organisation, it refers to the volume of
CO2 released as a consequence of regular company activities, either directly or indirectly. Additionally, it
may signify the use of fossil fuels in a product or commodity that is about to hit the market."
Office of Science and Technology in Parliament (POST 2006) "The total quantity of CO2 and other
greenhouse gases released over the entire life cycle of a process or product is known as the "carbon footprint."
The varying global warming impacts of other greenhouse gases are taken into consideration by expressing it
as grammes of CO2 equivalent per kilowatt hour of production (gCO2eq/kWh)."
According to Haven (2007), the life-cycle study of an office chair's carbon footprint "takes into consideration
materials, production, transport, usage, and disposal at every step of development." 3 This suggests a more
thorough strategy, which is seldom discussed in other publications. However, neither a definition nor a
methodological explanation are provided.
The assessment of a company's carbon footprint, according to Eckel (2007), "is... not simply calculating
energy usage but also with increasing every scrap of data from every part of the business processes." Yet
again, the analysis's purview is not made explicit.
The UK's Carbon Trust 4 has released a draught approach for comment in an effort to increase awareness of
what a product's carbon footprint is (Carbon Trust 2007). It is emphasised that only input, output, and unit
operations that are directly related to the product should be taken into account. Some indirect emissions, such
as those from employees travelling to and from the plant, are not taken into account.
The carbon footprint is considered a component of the ecological footprint by the Global Footprint Network,
an organisation that annually prepares "National Footprint Accounts" (Wackernagel et al., 2005). The term
"carbon footprint" is used interchangeably with "fossil fuel footprint," "demand on CO2 area," and "demand
on CO2 land."
Sundin and Ranganathan agree that controlling carbon emissions is one of the first actions any organisation
can take to create a successful plan to combat climate change (2002). Making the company and its related
processes carbon neutral is one way to do this.
Measuring one's company's carbon footprint has a number of advantages. In addition to being the first rung
on the carbon neutrality ladder, it aids in identifying the dangers and possibilities related to GHG emissions
(Sundin and Ranganathan, 2002). Additionally, determining GHG emissions may be necessary for the
company's operating licence, public reporting, and other GHG initiatives (Sundin and Ranganathan, 2002).
(World Resources Institute and World Business Council for Sustainable Development, 2004). In India,
measuring one's carbon footprint is mainly done on a voluntary basis by different business organisations.
According to Murray and Dey (2009), the concept of carbon neutrality refers to "offsetting the damage to the
atmosphere caused by one type of GHG-producing human activity through another human activity that either
reduces CO2 emissions by an equal amount; or prevents an equal amount from being generated by an essential
CO2 producing human activity by substituting a non- or low-carbon producing alternative."
We understand that the buildup of greenhouse gases in the Earth's atmosphere creates hazards that might have
a big impact on society and ecosystems, according to the Fortune magazine article from April 17, 2006. We
think that the hazards warrant taking action right now. However, the initiatives must take into account the
lingering costs and uncertainty. According to reports, persons who are worried about climate change and the
potential role that human (anthropogenic) emissions may have in accelerating the pace of climate change
continue to explore CO2 collection and sequestration.
Recent research by Cefic allowed for the computation of aggregate CO2 emission numbers by gathering
information on the tonnes and kilometres transported by various forms of transportation. The difficulties in
selecting appropriate emission factors for the different transport modes have been brought to light by this
inaugural experiment.
Five steps have been suggested by the UK Carbon Trust for the measurement and reporting of carbon
emissions by companies. Some participants in the discussion think that decreasing CO2 emissions from the
use of all fossil fuels may stop climate change. Power plants have been a topic of controversy in various places
since they are significant contributors of CO2 emissions. Amine scrubbing is an antiquated and ineffective
method for removing CO2 from pulverised coal-fired power plants that is now commercially accessible.
Therefore, CO2 collection will dramatically increase the operational expenses of the current fleet of fossil
fuel-based plants without advancements in technology.
A joint declaration on climate change was released in May 2007 by the Joint Sciences Academies, which
included representatives from Brazil, Canada, China, France, Germany, India, Italy, Japan, Russia, the United
Kingdom, and the United States. The group accepts that there is uncertainty and that the climate system will
change slowly. According to the joint declaration, it will never be possible to fully comprehend a system as
complicated as the global climate. But there is now enough proof that major global warming is taking place.
The evidence is provided by direct measurements of increasing surface air and subsurface ocean temperatures
as well as by natural phenomena including rising global sea levels on average, receding glaciers, and
modifications to several physical and biological systems. The majority of the warming in recent decades is
probably caused by human activity. The Earth's climate has already changed as a result of this warming.
Changes in greenhouse gas concentrations have a gradual effect on many components of the climate system.
Even if greenhouse gas emissions were to suddenly settle at current levels, the climate would still shift as it
adapted to the recent rise in emissions. Thus, more climatic shifts are inevitable. Countries must be ready for
them.
Douglas lists seven advanced technology choices in the 2007 EPRI Journal article Pathways to Sustainable
Power In a Carbon Constrained World that, if aggressively adopted, may cut CO2 emissions collectively by
nearly 45 percent from 2007 levels in 2030. The portfolio of technologies includes CO2 capture and storage,
advanced coal power plants, renewable energy, advanced light water nuclear reactors, plug-in hybrid electric
cars, distributed energy sources, and advanced light water nuclear reactors.
According to Coddington and Reynolds (2007), improved oil recovery procedures are another significant and
significant usage for CO2. Due to its chemical makeup, carbon dioxide is well suited to extract hydrocarbon
resources. Large amounts of oil that would otherwise be unrecoverable are actually scrubbed from the injection
zone by the supercritical carbon dioxide molecule when it enters the reservoir as a supercritical fluid.
According to Johnson (2010), carbon footprints are the total greenhouse-gas emissions of a product or service
over the course of their useful lives (or life cycle). Carbon footprint, as defined by Weidmann and Minx
(2008), is a measurement of the carbon dioxide emissions generated both directly and indirectly by an activity
or during the course of a product's life cycle.
According to Johnson (2007) and Peters (2010), the carbon footprint of an individual, home, business, product,
or certain geographic areas and nations may be measured. For the purpose of calculating carbon footprints, a
number of recommendations, including the IPCC guidelines, ISO 14064, and Green House Gas (GHG)
Protocol, are available. The GHG protocol, which was initially published in 2001 as a result of a
multistakeholder cooperation of corporations, non-governmental organisations (NGOs), governments, and
others, is one of the most often used protocols for measuring emissions (World Resources Institute and World
Business Council for Sustainable Development, 2004). The protocol's updated version was released in 2004.
The GHG Protocol was the one who first proposed the idea of scopes of emissions, which prevented duplicate
counting and assigned responsibility for emissions to the emitter (Aggarwal, 2009). The Carbon Trust
Standard, Carbon Disclosure Project, ISO 14064 standard, and many more standards and calculators have all
been developed using the GHG protocol as a building component (Donoghue, 2009).
As Lord Turner correctly noted, measuring carbon emissions is the first step toward controlling them since in
business, what is measured is controlled (Deloitte, 2010). In order to minimise these emissions over a certain
time period, it is crucial to identify emission reduction objectives after the footprint calculation. Lowering a
corporation's GHG emissions may be accomplished through modifying technical procedures, improving
energy efficiency, and changing employee behaviour.
Eckel (2007) proposes putting into practise energy-saving measures including switching from normal
incandescent light bulbs to compact fluorescent light bulbs and turning off the lights when they are not
required. These adjustments are probably going to reduce emissions while also saving energy. The related cost
reductions are also difficult to ignore (Deloitte LLP, 2010). Simple actions like turning off superfluous lights,
keeping the air conditioning at 25°C instead of 24°C, or driving fuel-efficient cars, for example, are likely to
reduce the company's power and fuel expenditures, resulting in significant cost savings for the business. The
company's brand image is enhanced by the adoption of the emission reduction initiatives, providing it a
competitive advantage in the market.
The act of substituting avoided emissions for generated emissions is known as offseting (Murray and Dey,
2009). The act of someone else who promises to alter their behaviour in order to eliminate or avoid causing a
comparable level of damage compensates for the harm caused by one's emissions (Murray and Dey, 2009).
For instance, a business may purchase Renewable Energy Credits (RECs) from the market and subsequently
retire them to offset its carbon emissions.
Due to the availability of data, industrialised nations are the focus of the majority of research on carbon
footprint. Previous carbon footprint calculations for Indian families were made by Parikh et al (2011).
Associated research examines consumption pattern disparities between income categories and their carbon
dioxide consequences using IO-data from 1989–90 and household data from 1987–88. The affluent enjoy a
more carbon-intensive lifestyle, as shown by the fact that metropolitan emission levels are 15 times higher
than those of the rural poor.
Previous carbon footprint calculations for Indian families were made by Parikh et al (1997). Associated
research examines consumption pattern disparities between income categories and their carbon dioxide
consequences using IO-data from 1989–90 and household data from 1987–88. The affluent enjoy a more
carbon-intensive lifestyle, as shown by the fact that metropolitan emission levels are 15 times higher than
those of the rural poor.
In addition to carbon footprints, Pachauri and Spreng (2002) assessed the closely linked energy needs of Indian
families for the years 1983–1984, 1989–1990, and 1993–1994. Using IO-analysis, they discover that
household energy needs have dramatically grown over time, with rising income, population growth, and rising
energy intensity in the food and agriculture sectors serving as the primary drivers. Pachauri and Spreng (2002)
provided cross-sectional changes in total home energy demand based on this approach. An econometric
analysis finds income levels as the primary factor affecting variance in energy needs among families using
household consumption expenditure data for 1993–1994 paired with energy intensities reported by Pachauri
& Spreng (2002).
Lenzen (1998b) computed GHG intensities for Australian final consumption. According to IO-analysis, which
takes into account GHGs besides CO2 including CH4, N2O, CF4, and C2F6, the majority of GHG emissions
are eventually brought on by household spending.
Household carbon footprints for Australia Lenzen have been computed using data on household spending and
IO-derived carbon intensities in a manner that is comparable to our method (1998a). It is the first research to
calculate carbon footprints at the disaggregated household level using IO determined carbon intensities from
Lenzen (1998b) multiplied with spending on 376 commodities. In addition to the conclusion that household
energy and carbon needs are mostly determined by per capita income, it is discovered that, on average, rural
households spend their money on more energy-intensive goods than those from urban areas.
Lenzen et al. (2006) concentrate on the influence of income growth in a cross-country study, using a similar
technique to that used for energy. They are looking for evidence of the Environmental Kuznets Curve in order
to characterise household consumption habits in relation to their environmental effects (EKC). Their results
are consistent with other studies in the EKC energy literature since there is no apparent turning point in the
monotonic growth of energy demand with family spending.
Numerous studies often combine information on home spending with IO-derived carbon intensities to
determine household carbon footprints. Wier et al. (2001) examined the carbon footprint of Danish families
and identified factors inside the home that had a large impact on CO2 emissions. By integrating a hybrid
technique of process and input-output analysis with household spending data, Kerkhof et al. (2009) estimate
the CO2 emissions of households in the Netherlands, UK, Sweden, and Norway. Bin & Dowlatabadi (2005)
and Weber & Matthews (2008), both of which focused on US families, recently published similar
methodologies.
Studies that assess the health effects of pollution, such as those by Balachandran et al. (2000), Chowdhury et
al. (2007), Srivastava and Jain (2007a,b), Srivastava et al. (2009), and CPCB (2010), are successful in
generating concern about India's air quality and serving as a call to action.
Researchers Chhabra et al. (2001), Pande et al. (2002), HEI, (2004, 2010b), Wong et al. (2008), and
Balakrishnan et al. (2011) found that it is difficult to pinpoint specific sources and how much they contribute
to ambient pollution levels, let alone the effects of different control measures for a particular city. There are a
few integrated models that gather data at the regional level for Indian states and cities (Shah et al., 2000;
Balakrishnan et al., 2007; GAINS, 2010), as well as receptor modelling studies that identify source
contributions.
Through artificial chemical sinkage, K. S. Lackner and N. A. Johnston (2008) removed carbon dioxide from
the atmosphere. By this standard, wind energy, which is often used, is 100 times less concentrated than the
energy associated with atmospheric CO2. Calcium hydroxide, a key component of mortar, is an inexpensive
chemical extraction reagent that efficiently extracts CO2 and shows the practicality. The chemicals would be
continuously recycled, and the CO2 would be recovered and sent to a method of permanent disposal, such as
direct injection into underground reservoirs or the deep oceans, or mineral carbonation of serpentine deposits,
which permanently sequesters the CO2 as solid, safe, and inert mineral carbonates.
Using an aqueous partly miscible solvent made of so-called "lipophilic" amines is an unique way to overcome
this difficulty. Because of their low aqueous solubility, regeneration may result in the creation of a
thermomorphic miscibility gap (Agar et al., 2008). By achieving extensive CO2 desorption at temperatures
that are just above the lower critical phase transition temperatures (usually 60–70°C), low temperature or even
waste heat may be used for solvent regeneration.
The ideal method for reducing CO2 emissions from fossil fuel-powered power plants quickly is the aminebased post-combustion CO2 capture technique. The main issue with this method is the economics of the
process, which is notably shown by the energy needed for solvent regeneration. Mangalapally et al. (2009)
and Goto et al. (2009) presented some unnamed solvents that, according to their claims, can reduce
regeneration energy by 20–34 percent when compared to the benchmark system monoethanolamine (MEA).
However, the desorption must still be done using high-quality steam at 120°C.
The Puxty et al. (2009) unidentified absorbents have strong absorption performance for CO2 partial pressures
greater than 20 kPa, but they do not significantly outperform other absorbents at lower partial pressures. With
its rapid reaction rate and large loading capacity, aqueous ammonia seems to be a viable alternative solvent
for removing CO2, but nothing is known about its economics and regenerability (Gonzalez-Garza et. al.,
2009).
In 2009, Stolaroff et al. suggested employing sodium hydroxide spray to remove carbon dioxide from the
atmosphere.
Zhang (2007) and Tan (2008) published extensive research on the CO2 loading capacities, reaction kinetics,
regeneration rates, residual loadings, and other properties of the promising tertiary amine N,Ndimethylcyclohexylamine (DMCA) and secondary amine dipropylamine (DPA) (2010).
In their analysis of the improvements in greenhouse gas (GHG) inventory estimation reported in the Initial
National Communication compared to the earlier published estimates, Subodh Sharma, Sumana Bhattacharya,
and Amit Garg (2010) highlight the strengths, the gaps that still need to be filled, and the upcoming difficulties
for inventory refinement.
According to Zhang et al. (2010), the best method for reducing CO2 emissions from fossil fuel-powered power
plants quickly is the amine-based post-combustion CO2 capture technology.
Mangalapally et al. (2009) offered several unnamed solvents that they claim may reduce regeneration energy
by 20–34 percent when compared to the benchmark system monoethanolamine (MEA), although desorption
must still be done at 120°C with high-quality steam.
The Puxty et al. (2009) unidentified absorbents have strong absorption performance for CO2 partial pressures
greater than 20 kPa, but they do not significantly outperform other absorbents at lower partial pressures. With
its rapid reaction rate and large loading capacity, aqueous ammonia seems to be a viable alternative solvent
for removing CO2, but nothing is known about its economics and regenerability (Gonzalez-Garza et al., 2009).
In order to capture CO2 from the air, Dubey, Ziock, and Rueff (2010) found that an aqueous solution of
Ca(OH)2 is particularly effective. The majority of the CO2 is easily removed by simply bubbling air through
a few centimetres of Ca(OH)2 solution. Overall mass transfer resistance is not noticeably higher than gas
phase transfer resistance. The high level of extraction that Ca(OH)2 is able to accomplish comes at a
significant binding energy cost.
Dindore et al. (2010) used hydrophobic, porous polypropylene hollow fibre membranes and an aqueous
absorption liquid to study CO2 absorption in a membrane contactor. If the supply pressure was too low, the
absorption liquid soaked the pores, increasing the barrier to mass transfer. The input gas combination was
probably forced straight into the absorption liquid when the gas-side pressure was too high, preventing any
selective absorption from taking place and drastically reducing the process' selectivity.
Shah and co. (1997) According to research by Johnson et al. (2010), an accurate evaluation of urban air quality
and its management is hampered by a lack of relevant and/or trustworthy data, modelling skills, and
assessment capabilities.
Tushar Sakpal et al. (2011) studied two types of silica-supported amine sorbents: one in which a covalent bond
is formed between the amine and the solid support, and the other in which amine-containing polymers or
oligomers, such as polyethylene(PEI) or oligoethylimine, are loaded using a straightforward wet impregnation
method. According to the defined findings, SG-PEI that was synthesised had a larger amine loading than SGAPTS. It was discovered that amine-loaded silica gel significantly absorbs more CO2 than bare silica gel.
Zhang et al. (2011) concentrated on the removal of CO2 from CO2/N2 mixtures using an absorber membrane
contactor and came to the conclusion that in the case of just physical absorption, the liquid phase boundary
layer's resistance to mass transfer was the key element affecting the CO2 flow. The liquid flow rate had only
a minor impact on the performance in the case of chemical absorption (absorption with chemical reaction) of
CO2 in diethanolamine (DEA), and mass transfer at the feed gas side was the limiting factor.
Shelekhim et al. (2012) investigated membrane gas absorption processes using a mathematical methodology.
Despite the model's inability to quantitatively forecast the experimental results, it was able to pinpoint the
system's constraints.
For amine-based CO2 collecting systems, Anand B. Rao and Edward S. Rubin (2012) established costeffective CO2 control levels. To determine the effectiveness and price of amine-based CO2 collection from
power plant flue gas, the engineering economic process model, IECM-cs, has been developed in detail. Their
investigation demonstrates that a variety of plant design factors, including plant size, influence the amount of
CO2 management that is most successful. The cost-effectiveness of CO2 collection for post-combustion
systems may be significantly impacted by future advancements to existing amine-based CO2 capture systems.
Li et al. (2013) came to the conclusion that the wetting issue could be resolved and that there was no bubble
formation in the liquid phase when a dense layer was applied on top of the porous support. Of course, the
inclusion of this layer results in a large increase in the mass transfer resistance. Contrast this with the use of a
porous non-wetted membrane, which would not affect the absolute mass transfer coefficient.
In order to separate humidified CO2/N2 mixtures, Kosaraju et al. (2013) investigated asymmetric poly(4methyl-1-pentene) (PMP) hollow fibre membranes with an ultrathin dense skin layer for absorption and
desorption. MEA was used as the absorption liquid. They looked examined how the liquid's velocity affected
the total mass transfer coefficient as well as the CO2 level at the absorber outlet over time. After 55 days, a
long-term test revealed a decline in CO2 absorption capacity.
The reversible physisorption of CO2 in functionalized metal organic frameworks was studied by Subhadeep
Saha et al. in 2013. (MOFs). Due to their large specific surface area, adjustable surface structures, and low
framework density, MOFs have potential CO2 storage capacity. The majority of investigations in the literature
have been on MOFs made of d- or f-block components (e.g. cobalt, nickel, zinc, copper, gadolinium,
neodymium etc.). When compared to their non-functionalized counterparts, N-containing and fluorinated
MOFs are intended to achieve greater CO2 loading.
In their 2014 paper, Kannan Srinivasan et al. discussed the use of CO2 in the manufacture of gasoline, fuel
additives, and bioderived compounds. Given that there are gigatonnes of CO2 available, it can be used to
produce fuels and significant quantities of chemicals, which will help reduce the amount of CO2 in the
atmosphere. Though there aren't many financially successful technical solutions at the moment, technologies
that would not only slow the increase of CO2 in the atmosphere but also provide some sustainable choices for
the world's expanding population and energy needs are anticipated in this century.
The technological and economic features of the post-combustion CO2 capture (PCCC) methods were gathered
by P S Sai Prasad and KV Raghvan in 2014. Most of PCCC's business success is a result of technology. The
majority of adsorption- and membrane-based technology possibilities are still in the early stages of research
and development, making it difficult to make an accurate prediction of their success or failure at this point.
CO2 absorption in biphasic solvents with increased low temperature solvent regeneration was studied by Frank
Geuzebroek et al. in 2014. At different regeneration temperatures ranging from 50 to 95 oC, three solvent
compositions were investigated. With certain solvent formulations, a maximum recovery of 100 percent was
achieved at a regeneration temperature of 90 °C and a total gas flow rate of 300 ml/hr.
Human impact on the climate system is evident, according to the Intergovernmental Panel on Climate Change's
Fifth Assessment Report (Working Group I) (IPCC, 2013). The interaction between the climatic, ecological,
and socioeconomic systems means that certain effects of the higher GHG concentrations may take time to
manifest. Due to the time scales involved with climate processes and feedbacks, human warming and sea level
rise would continue for millennia even after the atmospheric quantity of CO2 stabilised. Over the course of a
human lifetime, certain climate system changes would be irreversible.
Examining anthropogenic CO2 emissions in the context of natural world processes is useful for understanding
how people affect atmospheric CO2 concentrations. The global carbon cycle, with the highest carbon
exchange fluxes naturally occurring between the atmosphere and the seas and between the atmosphere and the
terrestrial biosphere. Continuous flows of carbon into and out of the atmosphere are accounted for by natural
processes such primary production, respiration, ocean absorption, and photosynthesis.
In their landmark study on "stabilisation wedges," Pacala and Socolow (2014) provided the first complete
examination of the different climate solutions. In their study, the authors introduce a notion known as the
"stabilisation triangle," which idealises a 50-year drop in emissions from levels required to maintain
atmospheric concentrations at twice pre-industrial levels. They cut the triangle into wedges, each of which
represents a decrease of 1 Gt C every year, for a total reduction of 25 Gt C over the course of 50 years. The
units used in this section should be understood to be in terms of carbon, not carbon dioxide (1 tC = 3.7 t CO2).
The effort required to scale up present operations to the level required to accomplish a single wedge is then
calculated by analysing each of the many technologies that are already in use.
The first of China's seven experimental carbon trading programmes, Shenzhen, began trading in 2013, marking
a significant turning point. Informed by these pilots, China has likewise declared its aim to launch a national
ETS after 2016. In late 2013 and early 2014, further pilot projects will start in two provinces and four more
cities (Beijing, Tianjin, Chongqing, and Shanghai) (Hubei and Guangdong). These pilots should cover 700Mt
of CO2 emissions in total.
According to the WEO 2013 New Policies Scenario, from 2011 to 2035, India's CO2 emissions would rise by
3.4 percent year, making up 10% of the world's total emissions. The power and heat industry, which accounted
for 52 percent of CO2 in 2011, up from 40 percent in 1990, is responsible for a significant portion of these
emissions. Despite being one of the sectors with the fastest rising CO2 emissions, transportation accounted
for just 10% of all emissions in 2011.
More recent estimates show that India's capacity for renewable energy has continued to rise rapidly, reaching
23 GW in January 2012, or approximately 11% of total power capacity (MNRE, 2012; CEA, 2012). With 16
GW, or 70% of the total renewable capacity, wind had the biggest share, followed by small hydropower (14%),
and biogas cogeneration (9%). The capacity of solar PV, which makes up just 2% of all installed renewable
energy capacity at 481 MW, is predicted to rise rapidly over the next several years. The high percentage of
private ownership, which accounted for 86 percent of renewable energy in India in March 2012, is one
noteworthy feature.
India has formed an executive committee to assess the nine missions included in its National Action Plan on
Climate Change on a regular basis. The need to further mobilise resources to be made available under the
National Clean Energy Fund (NCEF) to undertake projects under the missions was one of the main activities
noted by the Executive Committee.
CHAPTER 3 METHODOLOGY
Adopting Low Carbon Technology
Low carbon technology is one of the technical strategies that can be adopted in buildings to reduce carbon
dioxide emissions. Low carbon technology refers to the technology that has a minimal output of GHG
emissions into the environment, specifically for CO2 emissions [26]. Examples of renewable and
sustainable energy technologies are evaporative cooling, passive ventilation and cooling, solar photovoltaic,
dehumidification, and energy recovery systems. These technologies have been proven to significantly help
to decrease emissions and promote energy savings in buildings. Through low carbon technology, the
development of basic strategy requirements of innovation-driven development in the building can also be
achieved [27]. However, the downside of the low carbon technology implementation is it might increase the
operation cost of buildings. Therefore, systematic consideration should be addressed carefully to ensure the
balance between the reduction of CO2 emissions and investment of the technology.
1.1.
Restriction Strategy
Closing down the operation in particular areas and shutting down associated devices is a straightforward
approach to minimizing the CO2 emissions and energy utilization in buildings. The most accessible
practice is to keep the doors closed and switching off the lights and electrical appliances of vacant rooms.
It is defined as the restriction strategy when this is practiced in public buildings. Most of the public buildings,
such as teaching blocks, libraries, and fitness centers, have been grouped into several sections according to the
usage rate. In these public buildings, restriction strategy is achievable if unused areas are closed, and users
have to gather in certain permitted areas to share the services. Hence, energy consumption is reduced. A
study reported the linkage between building occupant rate and energy consumption in their study [28]. A
significant decline in lighting and heating energy consumption per capita with the increase of occupant rate
has been displayed.
Nevertheless, when the occupant rate increases, it might lead to the dissatisfaction of occupants. In
general, high occupant rates usually reduce air quality, ultimately affecting the operational effectiveness of
the occupants. Therefore, the major obstacle of the restriction strategy is energy conservation refuting the
occupants’ satisfaction.
1.2.
Impact Assessment of Building Process and Materials
Understanding the entire building process is very important in mitigating CO2 emissions. These
processes include extraction, manufacturing, transportation, construction, maintenance, and disposal.
Wide ranges of material are utilized in buildings that use energy and release CO2 through its life cycle, which
is regarded as embodied energy and embodied carbon. As part of mitigation measures, assessment of
embodied carbon of building materials is one of the fundamental approaches that can have a positive impact
on carbon footprint. The selection of appropriate sustainable building materials can reduce about 30% of
embodied CO2 emissions over a lifespan of the building [29,30]. Through this assessment, it has been
reported that reinforced concrete and clay bricks are the most carbon-emitting materials leading to
approximately 60% to 70% of the total embodied carbon [31,32]. Detailed inventories on building materials
and embodied carbon are presented in Hammond and Jones [33,34]. Besides, to reduce CO2 emissions or
meet the emissions targets, sustainable or low carbon materials can be considered in the manufacturing
process. Low carbon cement, timber, straw, and compressed Earth, which has lower carbon footprints are
some excellent alternatives.
L
QTCMc = UCMri × mi
(3)
i=1
QTCMc is the total cost of building material in the embodied stage.
UCMri is the unit cost of a building material without considering recycling.
The carbon emission factors, the energy factors, and the unit cost of the building materials are reported in the
previous studies [37–40]. From this study, mortar, commercial concrete, wall materials, steel and doors, and windows
contribute to about 80% of carbon emission. Thus, CO2 emissions of buildings should be identified and analyzed
from the necessary structural forms. Hence mortar, commercial concrete, wall materials, and steel should be given
more attention when implementing CO2 emission mitigation measures.
Table 2. CO2 emissions, weight, cost, and the energy consumption of building materials [35].
Materials
CO2 Emissions
(kgCO2 e/m2)
Weight
(kg/m2)
Cost (RMB/m2;
USD/m2; EUR/m2)
Energy Consumption
(MJ/m2)
Steel
Commercial concrete
Wall materials
Mortar
PVC pipes
Polystyrene extrusion board
Architectural ceramics
Doors and windows
Water paints
Copper core conductor cables
Wood
Waterproof roll
Stone
Total
142.23
123.94
68.19
58.1
33.44
21.25
12.12
9.54
5.03
2.58
1.40
0.62
0.47
478.91
64.86
905.3
334.13
372.76
5.89
1.08
3.13
5.41
0.68
0.27
5.03
0.51
17.12
1716.16
279.54; 40.72; 34.20
440.06; 64.10; 53.84
37.88; 5.52; 4.63
29.61; 4.31; 3.62
7.56; 1.10; 0.92
15.06; 2.19; 1.84
3.19; 0.46; 0.39
70.5; 10.27; 8.63
7.76; 1.13; 0.95
14.07; 2.05; 1.72
6.61; 0.96; 0.81
4.25; 0.62; 0.52
5.43; 0.79; 0.66
921.51; 134.23; 112.75
1415.80
209.37
260.29
223.69
16.96
15.81
22.91
112.12
19.82
12.21
5.88
0.02
3.63
2318.50
In mitigating CO2, proposed solutions should also combine sustainable energy sources,
such as solar and wind energy and biofuels, in the operations of buildings through life cycle
assessment. The building sector has great potential to lessen CO2 emissions during its operational
stage by using less energy at the planning, building, and operation steps by increasing efficiency
and enhancing construction standards. The goal of the life cycle assessment is to reduce
environmental effects and costs. With this regard, a global assessment methodology was developed
in 2011 called EN 15978:2011, which provides the calculation steps and analysis rules for the
environmental performance assessment of new and existing buildings [41]. This strategy can
incorporate all periods of the building’s life cycle. For example, Hong Kong has analyzed the life
cycle of buildings under its jurisdiction. Their focus is to decrease energy usage by 25% from the
2005 level by 2030 [14]. The life cycle assessment can distinguish the life cycles of the structure
from the operation of the building [15]. The operation and embedded carbon footprint of the
building is considered in the construction and maintenance of the building. The construction
process includes CO2 emissions from the creation, development, maintenance, and substitution of
building materials and services of the building [15]. The energy used in maintenance corresponds
to the operation carbon footprint for a given fuel blend. Steps used in limiting the operation
carbon footprint can adversely affect the embedded carbon footprint.
On the other hand, aside from new buildings, impact assessment of historical or old buildings
should also be considered, which can be an appropriate solution to reduce CO2 emissions. As
reported in the literature, on average, buildings have an exceptionally long lifespan between 60
to 120 years. Based on this lifespan, historical or old buildings are still in use, and it is
expected that 80% of existing buildings will continue to be occupied in 2050 [42]. Understanding
of principles, materials, methods, risks, and technologies is essential towards decarbonization in
these buildings by analyzing their building materials and elements. A detailed life cycle
assessment can be carried out by taking into account several factors towards CO2 mitigations such
as operational energy performance, reuse, and sustainable refurbishment, retrofitting solutions,
building envelope thermal performance improvements, heating, cooling, ventilation and lighting
systems, and adaptation of passive measures [43,44].
2.
Conclusions
The building sector plays a significant part in the emissions of CO2 globally. The tremendous
production and release of CO2 have led to severe consequences and repercussions contributing to
climate change. The adverse effects of the non-sustainable built environment have not only put a
strain on the environment but also have affected humanity. This paper provided an overview of
the issues, impacts, and mitigation strategies in the building sector to reduce and control CO2
emissions. The energy sourced from fossil fuels is non-sustainable, and yet it accounts for a
large percentage of the energy used in the construction and operation processes. The strategies
to reduce CO2 in the building sector are enforcing standards and policy, conducting impact
assessment, adopting low carbon technology, and restricting energy utilization. If we continue with
the current approach for the building sector, it will be too late to rectify the mistakes of our
predecessors. The future of sustainable cities and communities will remain uncertain, and we might
fail to achieve global sustainable development goals. The building sector must be given enough
attention and care to reduce the rate of CO2 emissions. A comprehensive and thorough analysis
is necessary to study the CO2 emission mitigation measures in the building sector, and global
organizations must come up with a holistic framework to tackle the issue. For a more sustainable
future, it is crucial to implement drastic actions and measures to reduce CO2 emissions to aid the
fight in combating climate change.
CHAPTER 4 DATA ANALYSIS
1.1.
Cloud Model Basic Theory
1.1.1.
Definition of Cloud Model
Cloud model theory is a theory proposed by academician Deyi Li in 1995 based on
probability theory and fuzzy mathematics [62]. The cloud model can reflect the fuzziness
and randomness of things and realize the interconversion of qualitative concepts and
quantitative indicators. Set a theoretical domain as U, and C is a qualitative concept on U.
If for any quantitative value x and x € U, µ(x) is the affiliation of x to the qualitative concept
C. µ(x) is a random number within [0,1], and the affiliation cloud is the distribution of the
→ domain
∀
affiliation µ(x) over the thesis
U→
[63]. That is, the mathematical representation is µ(x):U
[0,1], x € U, x µ(x). An affiliated cloud is composed of multiple cloud droplets that react to
the overall characteristics of the qualitative concept C [64]. The cloud droplets
(x, µ(x)), whose generation process represents an uncertainty mapping between qualitative
concepts and quantitative values.
1.1.2.
Digital Features
The cloud model considers the vagueness, randomness, and discrete nature of the judged
objects, which is mainly portrayed by these three numerical features (Ex, En, He) [65]. The
expected value Ex denotes the center of the distribution of the theoretical domain; the entropy
En reflects the ambiguity degree of the judged object boundary, and the dispersion degree of
the cloud drops in the theoretical domain U; the super entropy He reflects the uncertainty of
the entropy En, namely, the thickness of the cloud, and also the degree of dispersion of the
cloud, namely, the randomness of the judged object [66].
1.2.
Comprehensive Evaluation of Cloud Models
Step 1: Generate metrics evaluation cloud
The weights of the index are calculated according to the C-OWA operator. The cloud
number characteristics of each index were calculated by Equation (11), and the results are
shown in Table 6. Based on the calculated cloud digital features of each indicator in the
indicator layer, the digital features of the guideline layer corresponding to each indicator are
calculated, as shown in Table 7. According to the numerical characteristics of the criterion
layer, a cloud generator is used to generate the evaluation cloud map of the criterion layer, as
shown in Figure 6.
Table 6. Numerical characteristics of the indicator layer.
Indicat
ors
Construction material
selection A11
Transportation Planning
A12
Energy-efficient design A13
Combined steel formwork
usage A21
Improved material utilization
A22
Green Material Utilization
A23
Construction solid waste
reduction A24
Material transportation
distance A25
Component storage A26
Ex
En
He
6.6
1.45
4
1.55
4
1.88
0.61
3
0.45
5
0.75
2
0.39
9
0.46
6
0.12
4
0.51
2
0.48
2
0.46
6
0.37
2
0.65
5
0.17
1
0.68
9
0.6
5.8
6.1
7.6
6.7
6.8
7
6.4
6.3
Use of new energy A31
6.2
Energy saving A32
5.8
Effective use of water
resources A33
Use of water-saving
equipment A34
Energy consumption A35
5.4
Equipment energy saving
management A36
Dust Control A41
5.1
4.6
5.1
6.2
1.85
5
1.70
5
1.55
4
1.50
4
1.35
4
1.70
5
1.50
4
1.55
4
1.25
3
1.65
4
1.60
4
1.42
9
1.80
0.70
9
0.50
Reduce exhaust emissions
A42
Solid waste disposal A43
6.8
Construction waste recycling
A44
Green Space Planning A45
6.6
6.2
6.8
Wastewater treatment A46
5.5
New Construction Process
A51
Construction Design A52
6.3
The use of new equipment
A53
Assembly rate A54
Standardized design and
production A55
6.1
6.3
7.3
7.1
5
1.50
4
1.35
4
1.35
4
2.05
5
1.62
9
1.52
9
1.15
3
1.70
5
1.88
1.62
9
4
0.29
0.58
8
0.46
1
0.51
9
0.39
3
0.34
3
0.32
2
0.46
6
0.18
0.57
7
Table 7. Numerical characteristics of guideline level indicators.
Indicators
Design Planning A1
Construction
Materials A2
Energy use A3
Architectural
Environment A4
Construction
Organization A5
Ex
6.19
0
6.83
6
5.42
1
6.38
6
6.66
2
En
1.63
7
1.62
9
1.50
3
1.64
5
1.61
1
He
0.61
1
0.40
8
0.52
3
0.46
0.37
6
Figure 6. Guideline layer index evaluation cloud.
The numerical characteristics of the target layer are calculated by Equation (12), according to the numerical characteristics of the criterion-level indicators in Table 7, and the
indicator weights. The results are Ex = 6.360, En = 1.611, and He = 0.470. The numerical
characteristics of the target layer obtained are used to generate a comprehensive evaluation
cloud of the carbon emission reduction effect of prefabricated buildings using MATLAB, as
shown in Figure 7. It can be clearly seen from the cloud that the carbon emission reduction
effect level of the prefabricated buildings is between level III and level IV, which is at an
acceptable level.
Figure 7. Comprehensive evaluation cloud chart of carbon emission reduction effect of
prefabri- cated buildings.
1.3.
Results and Discussion
1.3.1.
Case Discussion
In this section, the results obtained regarding the carbon emission reduction effect of
prefabricated buildings will be presented.
(1)
According to the comprehensive evaluation cloud in Figure 7 and the
weight values of the indicators in Table 5, the result is that the factors that significantly impact
carbon emission reduction in prefabricated buildings are the primary indicators of building materials.
Among the secondary index, the use of combination steel formwork A 21, the reduction in
construction solid waste A24, and the improvement in the material utilization rate A22 have an
essential impact on the evaluation of the indicator system. Using the cloud model to evaluate the
carbon reduction effect of the first-level indicators, the following weighting relationships can be
obtained: A2 > A5 > A4 > A1 > A3.
(2)
The future carbon emission reduction in prefabricated buildings can start
with building materials. Improving the utilization rate of building raw materials and reducing material
waste can improve the carbon emission reduction effect. According to the produc- tion characteristics
of prefabricated buildings, the construction formwork adopts combined steel formwork; this way can
reduce wood waste and control the carbon emissions of prefabricated buildings, thus promoting
carbon emission reduction.
(3)
Using the cloud model to evaluate the carbon reduction effect of
prefabricated buildings, a comprehensive evaluation cloud diagram can be obtained, as shown in
Figure 7. The carbon emission reduction effect of the prefabricated apartment building can be intuitively observed in Figure 7 to be at an acceptable level. The carbon reduction effect level of
the apartment was obtained from the evaluation model at an acceptable level, and this result is
consistent with the assessment results of the carbon reduction effect of the apartment by the
Henan Province prefabricated building industry. Its evaluation results have a certain significance
in promoting the evaluation of the carbon emission reduction effect of prefabricated buildings,
which is more conducive to promoting the sustainable development of prefabricated buildings.
1.3.2.
MODEL DISCUSSION
In relation to the method, the cloud model, combined with the building supply
chain, was applied in the analysis of the carbon emission reduction effect of prefabricated
buildings, with which it was possible to assign weights to each of the indexes, which allows
us to establish the model of the whole life cycle carbon emission reduction effect evaluation
of prefabricated buildings. The building supply chain can help us analyze carbon flow and
establish a corresponding indicator system.
Firstly, based on the supply chain of prefabricated buildings, the carbon flow for its
whole life cycle is analyzed by using literature analysis and the expert interview method
to establish an evaluation index system. The established index system can well reflect
the relevant factors affecting carbon emission reduction in the whole life cycle of
prefabricated buildings, and it provides a reference system for the study of carbon
emission reduction influencing factors of prefabricated buildings.
Secondly, the cloud model is used to conduct a comprehensive evaluation of the index
system. The cloud model recognizes the uncertainty transformation between qualitative
concepts and quantitative values, which effectively makes up for the lack of some traditional
evaluation models in dealing with uncertainty. Moreover, the evaluation results can be
analyzed visually and clearly through the cloud diagram to show the degree of influence
of the evaluation indexes on the carbon emission reduction effect, which is a more scientific
evaluation method.
Finally, the case was analyzed and verified using C-OWA to calculate the weights
of each index and the cloud model to generate the evaluation cloud map. The cloud
analysis shows that the comprehensive evaluation of the carbon emission reduction effect
of prefabricated buildings in this case is at an acceptable level.
The cloud model is a model to study the relationship between fuzziness and randomness, which is more responsive to the fuzziness and randomness of variables than the
traditional affiliation function, and can better deal with natural language, multiattribute decision making, and so on. The evaluation results are reflected in the mapping
relation- ship between qualitative and quantitative, and its processing results are more
intuitive and clear, and the evaluation process is more scientific. The evaluation model
based on the cloud model from the perspective of the construction supply chain
provides a new evaluation idea for the comprehensive evaluation of the carbon emission
reduction effect of prefabricated buildings.
It should be noted that in this work, we invited ten experts to rate the level of 26 indexes of the case according to a ten-point system and established the normalized matrix
starting from the use of the cloud method; however, it is necessary to establish an in-depth
evaluation of the value corresponding more precisely to each index.
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