## 2 Case Study  
The factory under study operates a single production line with a maximum annual capacity of 77,000 Mg of finished product. The plant holds the following certifications: ISO 9001 for Quality Management [19], ISO 14001 for Environmental Management [20], ISO 45001 for Occupational Health and Safety Management [21], and ISO 22000 for Food Safety Management [22]. These certifications attest to the implementation of an integrated management system, which is regularly audited both internally and externally. Natural gas is the primary fuel used in the facility, mainly for boilers and dryers. The primary function of the boiler is to generate steam for the extrusion process. It has a maximum capacity of 6500 kg h\({}^{-1}\) of steam at a maximum operating pressure of 10 bar. Under current conditions, it operates at 1800 kg h\({}^{-1}\), consuming approximately 100 m\({}^{3}\) h\({}^{-1}\) of natural gas. The dryer used in the pet food processing line includes three burners: two rated at 5802.8 W each and a smaller burner rated at 3798.2 W. It consumes approximately 200 m\({}^{3}\) h\({}^{-1}\) of natural gas. These stages involve the use of the boiler, which generates the steam required to cook ingredients during extrusion, and a dryer, which ensures a product shelf life of up to 18 months by reducing water activity and free moisture content, inhibiting microbial growth [23,24]. Unlike electrically powered equipment, it is important to highlight that both the boiler and the dryer operate on natural gas. As a result, they are not only the largest consumers of thermal energy but also the main contributors to GHG emissions during production. In terms of electrical energy, the plant has implemented several energy efficiency initiatives, including 100% LED lighting, motion-sensor lighting, and the stabilization of production line speeds. Additionally, the facility has installed a reverse osmosis system, which reduces calcium buildup in the water before it enters the boiler, thereby ensuring consistent water quality and lowering the energy required for heating. Furthermore, the plant recovers water from the production process to preheat water ex tracted from the well. This recovered water raises the temperature of incoming water from 5-10 \({}^{\circ}\)C to approximately 30 \({}^{\circ}\)C, improving overall thermal efficiency. In 2020, the total natural gas consumption reached 46,635 GJ. Electricity consumption includes lighting, water heating for showers and restrooms, water pumps, space heating in offices, computer systems, and other auxiliary uses. Total electricity consumption during the same year amounted to 34,312 GJ. Figure 1 presents the relationship between thermal energy consumption and pet food production. A clear correlation can be observed, as approximately 1 GJ of thermal energy is required to produce one Mg of pet food. In contrast, electricity consumption remains relatively stable regardless of production volume, averaging around 0.6 GJ of electricity per Mg produced. Figure 1 also illustrates that, since December 2020, there has been a decrease in electricity consumption per Mg produced. This improvement is attributed to increased production run speeds, which allow for a greater output in less time without compromising product quality, thereby enhancing energy efficiency. By comparing the types and quantities of energy used in the production process, as shown in Figure 1, it can be concluded that 62.3% of the total energy consumption is thermal, while electrical energy accounts for 37.7%. Notably, the electricity used is sourced from renewable energy, as established through agreements with the local utility provider. The above results in a lower environmental impact compared to thermal energy, which relies entirely on natural gas. Therefore, energy efficiency management is critical in the stages that require thermal input, specifically stages 3 (extrusion) and 4 (drying).