As the metaverse continues to blur the lines between virtual and physical worlds, digital twins—virtual counterparts of real-world entities—play a pivotal role in enabling seamless monitoring, simulation, and optimization. However, the growing reliance on digital twins raises pressing concerns about energy consumption and environmental sustainability. This chapter explores practical strategies to design and implement digital twins in ways that prioritize energy efficiency and ecological mindfulness. The discussion begins with an emphasis on integrating energy-conscious technologies like low-power sensors and edge computing systems to reduce processing demands and data transfer requirements. Advanced algorithms for real-time synchronization and predictive modeling are presented as key solutions for efficient resource management without compromising accuracy. The study also investigates how renewable energy sources can power data centers that host digital twin infrastructures. Moreover, fostering collaboration between digital twin ecosystems and smart energy grids is highlighted as a transformative approach. By aligning data and computational requirements with real-time energy availability, digital twins can dynamically adapt their operations to minimize environmental impact. This approach not only optimizes resource usage but also promotes the broader adoption of sustainable practices in virtual environments. Beyond the technological aspects, the research highlights the role of AI in enabling smarter resource allocation and flexible scaling of computational loads. Decentralized systems, such as blockchain, are examined as alternatives to traditional centralized models, offering a more sustainable and distributed approach. Real-world applications in areas like smart cities, healthcare, and industrial systems are explored to illustrate the tangible benefits of these sustainable practices. This work underscores the urgency of addressing the ecological impact of digital twin technology in the metaverse. It calls for collaboration among policymakers, technologists, and industry leaders to establish a framework for green computing in virtual environments. By reimagining digital twins through a sustainability lens, this study outlines a pathway toward a greener, more scalable metaverse that balances innovation with environmental responsibility.