**4.1 Methodology used for assessing the lifecycle impacts**

The methodology behind life cycle assessment (LCA) is to accumulate all the impacts originated from the inputs and outputs of a system starting from the "cradle to grave" and to give a total impact number for the system under discussion. Accordingly, in an attempt to exemplify the importance of recycling of denim from the perspective of its environmental impact, an experimental work regarding the life cycle assessment of a denim fabric with and without recycled fiber content was conducted. For the work, the inventory was based on the 2019 denim production figures of a Turkish denim manufacturer in their manufacturing plant in Turkey. As assessment tool, SimaPro software developed by the Pré Sustainability, was used. SimaPro is the leading life cycle assessment (LCA) software that has been used for more than 25 years by the industry and academics in more than 80 countries [51]. SimaPro uses two types of data: primary and secondary. The primary data involves the basics of a denim production such as the amount of cotton used to manufacture 1 m of denim, i.e., 0.5 kg cotton. This data is exclusive to the fabric production practices of the factory. The secondary data, however, comes from the database, and it includes the impacts originated from producing that much raw material (in our case cotton fiber) and all other inputs such as chemicals at every stage. For secondary data, Ecoinvent database that is embedded into the software and is the most common life cycle inventory (LCI) database worldwide is used [52].

**4.2 Selected impact categories**

*DOI: http://dx.doi.org/10.5772/intechopen.92793*

SimaPro software are presented in **Table 3**.

(**Table 2**).

**Figure 3.**

*LCA calculation process.*

*4.3.1 System perspective*

system perspective.

**71**

One of the most important parts of life cycle assessment (LCA) is the outputs, in other words the environmental impacts of the product. With SimaPro software, it is possible to calculate over 100 environmental impact categories. For that reason, the academic- and industry-specific life cycle assessment (LCA) studies' guidelines and standards were surveyed to determine the environmental impacts for our study

*Understanding Denim Recycling: A Quantitative Study with Lifecycle Assessment Methodology*

With this taxonomy (**Table 2**), the commonly used environmental impact categories are listed for textiles. Consequently, based on the taxonomy given in **Table 1** and the raw material need for a denim fabric, five impact categories are selected. These impact categories, their definitions, and calculation methodologies within the

**4.3 Environmental impact as a rationale for denim fabric recycling**

As was mentioned above, the life cycle assessment (LCA) methodology is selected to calculate the environmental impacts of denim fabrics having different recycled contents in the same article so that the whole system can be taken into consideration. This means that we have to calculate the effect of every step in the life cycle to see the whole impact of our choices, including cultivation/production of the fiber, fabric production, garment manufacturing, distribution, consumer laundering, reuse, and final disposal [76–77]. One may think that using recycled cotton reduces the impact drastically, but parameters such as increased waste during production and increased energy usage should also be taken into account in a

If only one process or only fabric production as a system were calculated, this would have represented a single framed approach which is generally not preferable

The specifications of the denim article selected for the work is given in **Table 4**. Life cycle assessment (LCA) was conducted for 1 m of the article in accordance with the process steps including fiber cultivation, transportation, and all the production steps covered in the Turkish denim manufacturing company. The five environmental impacts are presented in **Figure 4**. For the comparative study, the results are

as calculations for production of single frames may lead to unwanted and

unforeseen effects elsewhere in the whole system.

*4.3.2 Five environmental impact categories*

To be able to perform life cycle assessment of a specific good or service, one needs to have inventory data for the complete supply chain. Due to the amount of data needed in order to be able to perform a life cycle assessment (LCA) study for a full supply chain, it is practically impossible to collect and organize the data of the complete background system. In that respect, the Ecoinvent database provides this very background system fulfilling the data required for the assessment. The Ecoinvent v3 database contains life cycle inventory (LCI) data taken from various sectors such as energy supply, agriculture, transport, building materials, production of chemicals, and metal production and consists of around 17,000 datasets, each of which describes a life cycle inventory (LCI) on a process level [52–53].

SimaPro software provides six libraries that each contain all the processes that are found in the Ecoinvent database but uses different system models and contains either unit or system processes. The three Ecoinvent system models are "allocation at point of substitution," "cutoff by classification," and "consequential." The system model "allocation at the point of substitution" follows the attributional approach in which burdens are attributed proportionally to specific processes. "Allocation, cutoff by classification" system model is based on the recycled content or cutoff approach in which the primary production of materials is always allocated to the primary user of a material. In this approach, if a material is recycled, the primary producer does not receive any credit for the provision of any recyclable materials available and burden-free to recycling processes; therefore recycled materials bear only the impacts of the recycling processes. The system model "substitution, consequential, long-term" uses different basic assumptions to assess the consequences of a change in an existing system and can be used for perspective studies and prediction of future changes [54]. In this study, for recycled materials "cutoff by classification" system model and for all other data "allocation at point of substitution" system model are used.

For life cycle assessment (LCA) of a product, the production of an item (e.g., denim fabric) is simulated, using both consumption and production data (primary) of a factory and the corresponding secondary data from the Ecoinvent database. The next step is to choose the environmental impacts to be calculated. The whole process is given in **Figure 3**.

*Understanding Denim Recycling: A Quantitative Study with Lifecycle Assessment Methodology DOI: http://dx.doi.org/10.5772/intechopen.92793*

**Figure 3.** *LCA calculation process.*

**4.1 Methodology used for assessing the lifecycle impacts**

*Waste in Textile and Leather Sectors*

The methodology behind life cycle assessment (LCA) is to accumulate all the impacts originated from the inputs and outputs of a system starting from the "cradle to grave" and to give a total impact number for the system under discussion. Accordingly, in an attempt to exemplify the importance of recycling of denim from the perspective of its environmental impact, an experimental work regarding the life cycle assessment of a denim fabric with and without recycled fiber content was conducted. For the work, the inventory was based on the 2019 denim production figures of a Turkish denim manufacturer in their manufacturing plant in Turkey. As assessment tool, SimaPro software developed by the Pré Sustainability, was used. SimaPro is the leading life cycle assessment (LCA) software that has been used for more than 25 years by the industry and academics in more than 80 countries [51]. SimaPro uses two types of data: primary and secondary. The primary data involves the basics of a denim production such as the amount of cotton used to manufacture 1 m of denim, i.e., 0.5 kg cotton. This data is exclusive to the fabric production practices of the factory. The secondary data, however, comes from the database, and it includes the impacts originated from producing that much raw material (in our case cotton fiber) and all other inputs such as chemicals at every stage. For secondary data, Ecoinvent database that is embedded into the software and is the

most common life cycle inventory (LCI) database worldwide is used [52].

which describes a life cycle inventory (LCI) on a process level [52–53].

tion" system model are used.

process is given in **Figure 3**.

**70**

To be able to perform life cycle assessment of a specific good or service, one needs to have inventory data for the complete supply chain. Due to the amount of data needed in order to be able to perform a life cycle assessment (LCA) study for a full supply chain, it is practically impossible to collect and organize the data of the complete background system. In that respect, the Ecoinvent database provides this very background system fulfilling the data required for the assessment. The Ecoinvent v3 database contains life cycle inventory (LCI) data taken from various sectors such as energy supply, agriculture, transport, building materials, production of chemicals, and metal production and consists of around 17,000 datasets, each of

SimaPro software provides six libraries that each contain all the processes that are found in the Ecoinvent database but uses different system models and contains either unit or system processes. The three Ecoinvent system models are "allocation at point of substitution," "cutoff by classification," and "consequential." The system model "allocation at the point of substitution" follows the attributional approach in which burdens are attributed proportionally to specific processes. "Allocation, cutoff by classification" system model is based on the recycled content or cutoff approach in which the primary production of materials is always allocated to the primary user of a material. In this approach, if a material is recycled, the primary producer does not receive any credit for the provision of any recyclable materials available and burden-free to recycling processes; therefore recycled materials bear only the impacts of the recycling processes. The system model "substitution, consequential, long-term" uses different basic assumptions to assess the consequences of a change in an existing system and can be used for perspective studies and prediction of future changes [54]. In this study, for recycled materials "cutoff by classification" system model and for all other data "allocation at point of substitu-

For life cycle assessment (LCA) of a product, the production of an item (e.g., denim fabric) is simulated, using both consumption and production data (primary) of a factory and the corresponding secondary data from the Ecoinvent database. The next step is to choose the environmental impacts to be calculated. The whole
