The European Engineering Learning Innovation and Science Alliance (EELISA) Challenges represent a pioneering initiative in fostering student-led, multidisciplinary projects across European universities. During the 2023-2024 academic year, a challenge was introduced focusing on circular economy solutions for construction and demolition waste. The approach emphasized autonomous student work and innovative idea development. However, the initiative encountered significant challenges, particularly in facilitating effective collaboration between students from diverse schools and universities, leading to limited success in achieving project goals.

In the 2024-2025 iteration, targeted adjustments were implemented to address the identified shortcomings, including enhanced communication strategies, structured guidance, and more integrated support for inter-university collaboration. This paper presents a comparative analysis of both experiences, evaluating whether the corrective measures have effectively resolved the earlier challenges. Furthermore, it identifies key areas for improvement and offers actionable recommendations for future implementations of similar initiatives. By reflecting on these two consecutive years, the study aims to provide valuable insights into optimizing cross-disciplinary and cross-institutional student projects in the context of engineering education and sustainability.

Keywords: EELISA Challenges, Circular Economy in Construction, Educational Challenges in Circular Economy.