Rapid industrialization around the globe has escalated environmental pollution, which has a severe impact on the environment and public health. Consequently, reducing pollution and ecological safeguard has become a prime concern of most cities around the world. In such a scenario, support from businesses and industries is essential for environmental protection. Each industrialist needs to assess their activities, understand how it affects the environment, and plan the eco-action to optimize their cleanliness. One crucial tool to enhance the environmental performance and support the sustainable development of businesses and industries is Life Cycle Assessment (LCA), also known as Life-Cycle Analysis. 

LCA Overview:

LCA is an assessment technique to measure the overall (cradle-to-grave) environmental impacts of a product, material, process, or activity (U. S. EPA, 2006). According to Curran (1996), it is a scientific tool to evaluate the potential environmental impacts of a system or product under study associated at all stages of product development. 

LCA quantifies all environmental effects caused by the inputs and outputs of a product or a process. Therefore, the analysis is based on the so-called ‘functional unit’, which may be a unit of material (e.g. a kg of steel of given composition and quality) or a unit of energy (e.g. a kW hour of electricity) (Jonker and Harmsen, 2012). LCA facilitates the decisions and policies of a product or service. 

LCA contributes to reducing environmental impact by redesigning the product or system that requires fewer resources and reducing the release of nonrenewable and toxic materials (Brusseau, 2019). As the tool quantifies the overall environmental and economic impact of the product, decision-makers not only know the actual resource consumption of their product and the effect of the product on the environment but also will have the opportunity to improve their product or to select the most effective method in the long run (Curran, 2016). 

When incorporated in the early phase of the system design and manufacturing process, this approach will allow producing environmentally friendly and sustainable goods. Thus, the LCA application support business model and environmental policies related to sustainable consumption and production (SCP). Moreover, it helps establish the baseline (e.g. energy and resource constraints) for specific products or processes (U. S. EPA, 2006).

International Standards organization (ISO) developed the LCA standards to regulate the LCA system. International standard documents ISO 14040 and ISO 14044 details the requirements and guidelines for LCA (Finkbeiner, 2014).

Components of LCA:

The LCA methodology is a standardized and staged process. In general, LCA has four components, as explained below: (Brusseau, 2019; Curran, 2016; Jonker and Harmsen, 2012; SETAC, 1993).  

I. Goal Definition and Scoping 

It is essential to conceptualize the product's design, process, or service to obtain the most significant results.  This stage defines and describes the LCA project's goal and purpose, including life cycle environmental impacts into the evaluation process. The goal definition and scoping include the functional unit to determine the time and resources required. Defining the functional unit determines the type of alternatives to be taken and facilitates the product or process design (Jonker and Harmsen, 2012; U. S. EPA, 2006). 

This phase also creates the initial boundaries to define what to be incorporated in the specific LCA (Jonker and Harmsen, 2012). Moreover, it defines the beginning and end of the particular life cycle and draws the relationship between technical and natural system. It also defines time and location boundaries. Location boundary is essential as the environmental requirements and the consumer behaviours differ in different locations. Similarly, the time boundary is necessary to get the relevant data (Curran, 2016).

Goal definition and scoping is a crucial determinations stage where purpose and the insight interest define the survey framework; hence, determining the further steps. This stage may concern the intensity of the survey, required specificity, quality data, the selection of the effect parameters about the impact assessment, and the revealing possibilities within the decision-making process framework (Klopffer & Grahl, 2009).

According to ISO 14040, LCA's scoping outlines the following vital parameters (Curran, 2016).

• The product system and its functions
• The functional unit
• Technical, geographical, and temporal system boundaries
• Allocation methods
• Data requirements, availability, and quality
• Assumptions, limitations, and restrictions of the study
• Type of critical review (if any)
• Type and format of the report needed

II. Inventory Analysis

The inventory analysis involves quantifying all life steps of a product or process, such as energy (raw materials) requirements, emissions, material flow, and environmental releases. This stage also determines the impact of inputs and outputs on the environment (Jonker and Harmsen, 2012). 

An inventory analysis provides data or information, which contains the generation of environmental (air, water, land) pollutants, amount of energy, and materials consumed. The remaining LCA process depends upon the quality of the data collected during the life cycle inventory (LCI).  The inventory analysis can be useful to make local or national government policy regarding environmental emissions (U. S. EPA, 2006).

LCI covers the following steps (Sonnemann & Vigon, 2011; U. S. EPA, 2006; DEAT, 2004):

i. Designing a flow diagram of the process

A flow diagram outlines the inputs and outputs of a system or process, including interrelationships using a reference case. The initial boundaries created in the goal definition and scoping stage are used as system boundaries for the flow diagram. The more detail flow diagram provides highly significant results.

ii. Development a data collection plan

A suitable data collection plan ensures the accuracy and quality of the data. The critical elements of the data collection plan include: defining data quality, classifying data types, sources, and indicators, and preparing a data collection worksheet and checklist. Also, it provides lists that specify the measurement units. 

The data collection plan helps meet the decision-makers expectations and compare the decision made with the reference case. 

iii. Description of data collection

This phase describes the data collection and calculation techniques for each data types. It is essential to mention the time and location of the collected data.  This phase involves desk review, site survey, and expert suggestions to generate the required data. 

Depending on the data types, data can be categorized as foreground data (data collector) and background data (data from user groups, stakeholders, records, etc.).

iv. Data analysis, evaluation and reporting results

After completing data input and analysis, the final report should include a thorough description of the analysis method, system boundary, assumptions, and the basis for comparison. 

The report is crucial to explain the methodology used to analyze the data, any irregularities on data provided, and any other exceptional cases. The inventory analysis result is a list of the quantity and quality of environmental pollutants and the amount of energy and materials used. 

III. Impact Assessment

At this stage, the life cycle impact assessment (LCIA) of the material and energy flow of the process or products is performed through an environmental and human health lens. Therefore, the impact assessment focusses on mitigating the ecological and social health effects and reducing natural resource depletion (U. S. EPA, 2006).

The impact assessment includes each environmental effect that has the required data and a suitable model for description. Thus, the impact assessment supports identifying, briefing, and quantifying the product or system's potential environmental impacts and information (Klopffer & Grahl, 2009). 

The inventory data showing similar impacts are transformed into particular impact categories having a standardized unit. The impact categories include sorting on a normal basis or ranking on an ordinary basis or a given hierarchy (Khoshnevisan et al., 2018).

The properties of a defined substance in a specific environment emit a specified polluting substance. For example, released greenhouse gases, such as carbon dioxide and Nitrous oxide, are categorized as ‘global warming potential’ substances. In general, Impact assessment includes: 

a. Global warming potential (GWP) 

b. (Tropospheric) photochemical ozone creation (POCP) 

c. (Stratospheric) ozone depletion (ODP) 

d. Land use

e. Ecotoxicity (ETP)

f. Eutrophication (NP) 

g. Acidification (AP) 

h. Human toxicity (HTP) 

i. Radiation

j. Thermal Pollution (Dispersion of heat)

These impact categories explain the potential effects of the system or output on human and the environment, which differs to their spatial level, i.e. global, regional or local impacts (Jonker and Harmsen, 2012; Klopffer & Grahl, 2009). 

After classifying the emissions to their respective environmental impact, an assessment is needed to identify the quantitative and qualitative emissions impact. The tools like conversion factors or so-called equivalency factors are used to assess the emissions' environmental effects (Jonker and Harmsen, 2012).

IV. Interpretation

For the goal and scope defined previously, the inventory analysis and impact assessment results are analyzed, and the limitations are evaluated through sensitivity and uncertainty analysis. Furthermore, the conclusions are derived from the study based on which the recommendations are made. The assessment facilitates significant improvements in the design or process, or product (Brusseau, 2019; Khoshnevisan et al., 2018). 

Applications of LCA:

Incorporating LCA at an early stage of system design will lead the businesses towards a sustainable direction, improves brand value, and provides several additional benefits. Some of the applications of LCA are shown in figure 2 above and are explained below. 

1. Allow cost savings

As LCA assesses the product’s environmental and economic impact right from the raw material acquisition to delivery of the final product, it helps identify the potential upcoming operational efficiencies. A data-driven approach improves operational efficiencies with resource use optimization, reduced power consumption, waste generation, and emissions. For example, an LCA of a DVD and Blu-ray disc manufacturing company provided them with an opportunity to reduce 13% raw material consumption, a 20% decrease in transport emission, and $40M cost savings annually(Deloitte, 2012).

2. Provide suitable alternatives

LCA provides possible alternatives to different products. A decision-maker can compare the entire production system and choose the less polluting product, service, or activity. For example: When a single process is considered among two products, an object may appear more environmentally friendly than others. But, through the LCA approach, a detailed study of the whole system may create the opposite scenario, i.e., the product observed with less environmental impact may have more significant cradle-to-grave environmental impacts (Scientific Applications International Corporation (SAIC), 2006).

3. Develop and improve product or activity

LCA helps construct a sustainable product or design by analyzing the input (raw) materials, processing and producing product remaining under the environmental, social, and economic criteria (Deloitte, 2012).

The credibility earned through disclosing the LCA-based information favours the attitude towards business and the brand. It will favourably influence the opinion and behavioural intents towards obtaining the goods (Molina-Murillo & Smith, 2009).

4. Evaluate the environmental impact 

LCA contributes to assessing the environmental effect of product or activity by quantifying pollutants' emissions to water, land, and air in each life cycle stage and their possible consequences to the local or global level (Brusseau, 2019).

Challenges of LCA:

Holding a vital role in analyzing the sustainability of an activity or a product, the LCA may generate uncertainties that may be increasing with the impact level of the process.  This may be due to the vast quantities of measured and replicated data and the basic modelling of complex environmental cause-effect scenarios (Hellweg & Canals, 2014).

1. Availability of reliable data

Sometimes the data at each stage of product development may not quantify material inputs and outputs. The availability of reliable data sources may have a significant impact on the final results. Data shortage and regional limitations of data are available for most categories, which shortly includes a natural disaster, human and ecotoxicity, which will undoubtedly produce unreliable data scores and results (Hellweg & Canals, 2014; U. S. EPA, 2006).

2. Incompetent LCA expertise

Mostly in developing countries, there is incompetent expertise for executing LCA studies. There has been a gap in understanding the communication between methodology and the study output to the project leaders and policymakers (Owens, 1997).

3. Assessing environmental impacts

It is essential to define which environmental parameters, such as resource utilization, power consumption, and pollution, are most concerned about and have a more significant impact in the long run. Besides, the reliability of the environmental assessment scores depends upon the skill of the LCA professionals.

4. Undertakes linearity of the impact

LCA presumes the linearity of the environmental impact, which may not be accurate in all cases. For example, LCA considers the more considerable amount of pollutants; the larger is the effect, which may depend on local conditions or critical loads (DEAT, 2004).