These proceedings present selected contributions from the 15th International Conference on Green Technology 2025 (ICGT 2025), convened in Malang, Indonesia, on 29–30 July 2025 in a hybrid format. The conference was hosted by UIN Maulana Malik Ibrahim Malang and designed as an interdisciplinary meeting point for scholars and practitioners working at the intersection of scientific inquiry, technological development, and environmental responsibility.

The conference theme “From Green Ideas to Global Action: Science and Technology for A Better Future” signals a deliberate shift from conceptual aspiration to implementable outcomes. It invites participants to treat sustainability not as a decorative label, but as a rigorous agenda: one that demands verifiable methods, transparent evidence, and solutions that remain credible when translated from laboratories and studios into policy, infrastructure, and daily life. Some papers in this volume offer incremental refinements; others take bolder methodological or conceptual steps. Together, they reflect a shared commitment to research that can travel across disciplines, across sectors, and across the gap between analysis and intervention.

Across keynote and parallel sessions, ICGT 2025 accommodated a wide spectrum of work, including (but not limited to) environmental science and climate-related studies, renewable energy and resource efficiency, sustainable architecture and urban systems, digital approaches for sustainability, advanced materials, waste and circularity strategies, and resilient infrastructure. The diversity of these domains is not incidental. Green technology, by its nature, rewards cross-fertilization: robust engineering benefits from ecological intelligence; sound environmental decisions increasingly rely on computation, measurement, and design thinking.

We hope this volume serves not only as a record of presentations, but also as a working reference one that supports further research, sharper debate, and collaborations capable of producing measurable environmental and societal benefit.