Our present research, starting from a previous study, aimed to define a methodological approach for sustainable lighting designs in a historical library, focusing on lighting quality, mainly obtained from the optimal use of natural light and its combination with the artificial one. A historical Florentine monastery, which is now a university library, was used as a pilot project. The proposed method forms an essential part of widening and deepening the recent study. Results have shown that this method will allow for adaptive lighting, based on the optimal control and use of natural light, historical–philological re-reading of the space, cultural heritage preventive protection and conservation, with the aim of building adaptive reuse, and it can be extended to similar cultural heritage cases, but also non-listed buildings and current designs. This research demonstrates how a correct natural lighting design can be a tool for sustainable refurbishment, guaranteeing cultural heritage conservation and preventive protection, and recovery of the historical, architectural and philological value of old and/or listed buildings, which have been converted to uses, often diametrically opposed to the original ones.

Sustainable lighting designs, with a view to achieve an adaptive reuse, refurbishment and conservative rehabilitation of cultural heritage, focusing on lighting quality, mainly obtained from the optimal use of natural light combined with artificial one, is the main aim of our present research. A historical Florentine monastery, which was turned into a university library, i.e. Santa Marta University Library in Florence, was used as a pilot project. Energy saving, natural light control combined with artificial light regulation, sustainable and quality lighting by means of optic fiber textile integration, acted as fundamentals of the proposed sustainable adaptive, non-invasive, reversible and easily removable lighting design. The integrated use of natural light with LED systems and optic fibers by means of a command structure made with supervision and home automation systems based on Konnex, the first open building automation standard, allows lighting solutions for quality and environmental and energy sustainability in cultural heritage. Results showed that the proposed methodological approach allows lighting proposals with the aim of building adaptive reuse, based on architectural structure optimal use, historical–philological reading of the indoor environment, cultural heritage (CH) preventive protection and conservation, but also people and works of art “health and well-being”.