Accelerated economic development and rising energy consumption pose increasing challenges in the context of sustainable development and environmental preservation. Climate change, depletion of natural resources, and the global energy crisis have become central themes on the global agenda. In this environment, the concept of sustainable development becomes a fundamental framework for guiding political, economic, and social activities toward achieving a long-term balance between economic growth, social justice, and ecological sustainability. Sustainable development encompasses an integrated approach based on responsible resource management, environmental preservation, and the creation of a fairer society. Its relevance is evident in the contemporary world, where the consequences of unsustainable practices, such as air and water pollution, land degradation, and loss of biodiversity, are becoming increasingly apparent. The global community has recognized the need for a paradigm shift in development, directing efforts toward reducing harmful gas emissions, utilizing renewable energy sources, and increasing energy efficiency. Energy efficiency is becoming a key element of sustainable development. Reducing energy consumption without sacrificing service or comfort levels allows societies to lessen their environmental impact while ensuring stable economic growth. Technological advancements in energy efficiency, along with the transition to renewable energy sources, play a crucial role in creating long-term sustainable energy systems. Croatia, as part of the global community and a member of the European Union, faces similar challenges. Achieving energy efficiency and sustainable development goals in Croatia requires the adaptation of national policies and alignment with European regulations and strategies. Despite progress in certain sectors, there is a need to further enhance the use of renewable energy sources and raise awareness of the importance of energy efficiency among citizens and businesses. This paper provides a framework for understanding the complexity of the relationship between energy needs, ecological sustainability, and economic development. Energy efficiency is not just a technical issue; it is also a socio-economic challenge that requires changes in behavior, education, and the political framework to achieve long-term sustainability.