In order to properly understand all the identified structures, the Team researched and benchmarked other classification methods that were being used. One of these was used by Lucchi, Garegnani, and Maturi (2014) in their paper “Architectural integration of photovoltaic systems in historic districts: The case study of Santiago de Compostela.” In the paper, they used the classification to determine which heritage structures could incorporate photovoltaic systems for a more sustainable energy source. The different levels of buildings were interfaced with possible interventions. This served as the basis for the San Pablo Heritage Zone Classification Index.
The SPHZ Classification Index lists six (6) different types of structures, each with their own levels depending on authenticity and integrity, as well as their contribution to the Heritage Zone.