Computing and Informatics

Software Re-Engineering (SRE) and Sustainable Software Engineering (SSE) are distinct yet interrelated paradigms in modern software development. SRE focuses on restructuring and optimizing existing software systems to improve functionality, maintainability, and adaptability, while SSE emphasizes incorporating environmentally responsible practices throughout the software life cycle. This paper presents a comparative analysis of these two approaches, highlighting their foundational principles, methodologies, challenges, and benefits. It underscores the necessity of embedding green and resource-efficient practices into re-engineering activities to achieve both operational excellence and environmental sustainability. By integrating SRE with SSE, organizations can enhance software quality, reduce ecological impact, and ensure long-term viability within the evolving software ecosystem. The study further advocates for energy-efficient design, user engagement, and renewable energy integration in software infrastructure. The findings aim to guide practitioners and researchers toward developing software systems that are not only optimized for performance but also aligned with sustainability goals, thus bridging the gap between technological advancement and environmental stewardship.