**4.4 Life cycle impact analysis (LCIA) methods**

One of the most important parts of an LCA is the outputs. With a Life Cycle Analysis software, SimaPro, for example, it is possible to calculate many impacts via a number of impact assessment methods [44].


#### **Table 1.**

*The life cycle module groups according to PCR for fabrics [43].*

The mill that is currently taken into consideration as the case study reviewed the industry guidelines and standards to determine which environmental impacts to focus on for their LCA studies. After scanning process, 5 impact categories were chosen to be assessed. These impacts, their definitions and calculation methodologies within the SimaPro 9.0.0 software are given in **Table 2**.

For EPDs, PCR documents guide the LCA practitioner on impact analysis. Defined in the PCR for fabrics, the calculated environmental impacts and inventory indicators should be separated into three life cycle stages as upstream processes (cradle-to-gate), core processes (gate-to-gate), and downstream processes (gateto-grave) and shall be reported as such. The environmental impact indicators that should be declared in EPDs and the calculation methodologies are described in the EPD program website [43, 50].

For example, the environmental impact indicator Global Warming Potential should be calculated for each life cycle module stated in **Table 1** in terms of fossil, biogenic, land use and land transformation and as total by using the calculation method GWP100, EN 15804. Version: August 2021 as stated in the program website as shown in **Table 3** [50].

In addition to the environmental impact categories, use of resources, output flows and waste categories are declared in EPD documents per declared unit for each life cycle stage according to the relevant PCR guidelines [43]. The use of resources and output flows and waste categories are given in **Tables 4** and **5**, respectively.

*Life-Cycle Assessment as a Next Level of Transparency in Denim Manufacturing DOI: http://dx.doi.org/10.5772/intechopen.110763*


#### **Table 2.**

*Selected environmental impact categories for the case study.*


**Table 3.**

*LCA results framework for Global Warming (GWP100a) indicator with mandatory life cycle stages and modules [50].*
