The course "Energy Optimization of Heritage Buildings" is offered during the second semester of the fifth year of Fundamentals of Architecture at the University of the Basque Country (EHU). It is an elective course with a workload of five ECTS credits. Throughout the course, students explore a broad range of topics that are increasingly relevant to contemporary architecture from technical, legal, economic, and aesthetic-compositional perspectives, with a particular focus on building systems and passive thermal conditioning.

This course employs a vertical learning methodology, promoting collaboration between undergraduate students enrolled in the course and Master's students from the Architecture program at EHU. Based on the Master's students' ongoing design projects, students in the Energy Optimization course are tasked with analyzing, modifying and proposing improvements to various building systems. Depending on the specific characteristics, limitations, strengths, or strategic aspects of each project, the systems under analysis may include fire safety systems, solar exposure, thermal and energy performance, HVAC systems, renewable energy systems, or water management.

During the second half of the course, an additional effort is made whereby each student team proposes improvements to help the project meet sustainable performance targets aligned with certifications such as the PassivHaus standard, BREEAM, LEED, Energy Performance Certificate, or similar schemes. This vertical collaboration therefore aims not only to meet the minimum requirements of current regulations but also to equip students with advanced competencies that are increasingly demanded in the architectural profession.

The vertical methodology is implemented through working groups composed of one Master's student (the project author) and two undergraduate students enrolled in the optimization course. The Master's student is not assessed as part of this course.

The course follows a continuous and formative assessment approach. Work is conducted during class time, and each session includes feedback and revisions with every team, which allows for iterative improvements and refinement of the project work throughout the semester.

This collaborative methodology has been in place since the 2018/2019 academic year. Since then, and through the current academic year (2024/2025), a substantial number of Master's projects have incorporated various sustainability goals. Notable outcomes include: 8 projects adapted their thermal envelope and ventilation systems to meet PassivHaus standards; 13 projects improved various building performance parameters to achieve an Energy Performance Certificate Class A; 13 projects were optimized to attain higher scores under the LEED certification system; 4 projects were enhanced in accordance with BREEAM criteria; 12 projects integrated renewable energy generation systems to achieve electrical self-sufficiency; 2 projects implemented water management systems; and 4 projects were assessed using the Sustainable Building Guide of the Basque Country.

This work has enabled students to appreciate how the integration of sustainability standards often requires rethinking projects from a broader perspective. Aspects such as mobility, site selection, air quality management, and the environmental impact of building materials—previously underexplored in the undergraduate Fundamentals of Architecture program—are now recognized as essential design considerations.

Keywords: Vertical methodology, sustainable goals, new requirements of the architecture.