It is our great pleasure to warmly invite you to the 2025 5th International Joint Conference on Energy and Environmental Engineering (CoEEE 2025), which will be held in Budapest, Hungary during July 25-27, 2025. The conference is dedicated to providing the platform and opportunities for researchers, scientists, engineers and scholars to exchange and share their experiences, new ideas and research in the common research field of Energy and Environmental Engineering, and to discuss practical issues, the challenges encountered as well as the solutions adopted.

Energy security, environmental degradation, soil & water loss, and climate change are the current and future grand challenges of the world. Energy and environmental engineering contribute immensely to these grand challenges and are important to the economic and ecological sustainability of the world. While the public has established the local-realism-based vision that the new energies (solar & wind power, biofuel, carbon capture and storage, etc.) and environmental engineering technologies (ecological restoration, wetlands, water & soil reservation, wastewater and sludge treatment, desalination, etc.) may be beneficial for resource conservation and climate change mitigation, the far-reaching ecological impact of these engineering projects to the environment is little explored. The ecosystem is an entity of complex network connections, where one slight change can affect the whole, but these complex interconnections remain little known to humans. For instance, it has been increasingly realized that all forms of renewable energy production rely on machines built with non-renewable minerals, which means that with current technologies, no form of renewable energy is 100% "renewable". The interlinkage of different ecological elements calls for a systems vision.

We recognize that the future for energy and environmental scientists is one where they will be working in interdisciplinary teams, especially in partnership with social scientists, to solve new, complex and evolving problems that will require innovative solutions. Therefore, we strongly encourage participation of interdisciplinary disciplines (such as social hydrology, energy and environmental policy, ecological economics, systems embodiment analysis, etc.) in this conference where multidisciplinary researches are presented.

CoEEE 2025 will be held in the beautiful city of Budapest, in spring, which is the wonderful season in Hungary. The conference will start with the registration and material collection on July 25, 2025, followed by two days of technical sessions consisting of plenary lectures and keynote speeches to overall audience and oral presentations and poster presentations by participants in various sessions as well as social networking events.

We truly believe that CoEEE 2025 will provide the best platform for all the participants to have spirited discussions and exchange insightful thoughts on the broad field of energy and environmental engineering. Finally, we do wish all of you to have a memorable experience on the conference and seize this opportunity to promote future international collaborations.