In 2015, The University of Burgos was commissioned to refurbish blocks numbers 4 and 5 of the city's former Military Hospital and convert them into blocks of classrooms. The buildings were originally built at the beginning of the 20th century.
It was decided that one of them would be refurbished in accordance with the Passive House standard (No 4) and the other one (No 5) using the building code currently in effect in Spain (CTE) so that the efficiency of both construction systems could be compared with real data from two buildings with identical envelopes used for the same purpose.
Glassed-in galleries outside the building envelope were added to connect the two buildings. This resulted in bigger classrooms and also established a relationship between the two buildings and their users, bringing the courtyard into the activity of both classroom blocks, which share this common space.
Obtaining the EnerPHit standard was quite tricky for this project. The facade was protected due to the building's status as a historical heritage building. This meant that openings in the facade could not be shrunk or enlarged, and no additional insulation could be added to the exterior. In spite of all these difficulties, the project achieved the EnerPHit certification in 2015.