**5. Conclusions**

This paper has provided the first systematic study of the vernacular daylighting provision in Moroccan heritage public bathhouses (hammams). It combines historical and architectural analyses of a representative sample of 13 working heritage structures to reveal tacit rules underlying the number, location and configuration of roof oculi. These are then restored in a working hammam to establish the first benchmark for levels of horizontal illuminance afforded by the vernacular system in the bathing spaces under real working conditions. The results reveal a recurrent pattern of oculi number and

configuration consisting of one to three rows of eight circular openings (of 18 to 20 cm in diameter) arranged along the roof vaults covering the bathing spaces.

The total area of roof openings for each bathing space was found to rarely exceed two percent of its internal floor area. Measurements of horizontal illuminance on the roof of sky conditions, as well as that of inside the bathing spaces, were carried out continuously and simultaneously in July, August and September of 2016 at 20 min intervals and at comparable locations. This has resulted in real time values, allowing for the calculation of daylight factor under real changing sky conditions. The results of horizontal illuminance measurements indicate that maximum levels are reached between 12:00 and 14:00 when the sun is high in the sky, but never exceeded 60 lx. The impact of the saturated air humidity on the daylight factor is evident in the hot room where the highest levels of DF are registered but suddenly decrease below that of the cold room as the air humidity levels reach almost 100%. Levels of horizontal illuminance are generally much lower than those recorded in previous studies in Ottoman baths and remain well below 60 lx as compared to 100 or 150 lx recorded in Ottoman hammams. Low levels of daylight are therefore a genuine experiential quality of Moroccan hammams afforded by small oculi in the vaults and domes of the bathing spaces.

This paper has provided a new understanding of the experienced luminous environment afforded by the vernacular daylighting system in Moroccan hammams and established the first benchmark for its rehabilitation in heritage structures and its future integration in new Moroccan hammams. Further studies are needed to investigate bather's sensorial experiences of heritage hammams daylighting ambiences to understand elements of comfort that are outside the norms of numerical quantification of light. As argued by Tregenza and Marjaldevic [19] in their review of half a century of research on daylighting, there are still important questions which fifty years of study have not fully answered: What are the criteria of good daylighting? What should be the central aim of the designer? What regulations or standards are required? "Describing lighting only in terms of illuminance is equivalent to describing music in terms of sound pressure level" [20]. As Bille and Sørensen [20] argue, light works as a significant constituent of experience. In their introduction to *an anthropology of luminosity*, they coin the term *lightscape* and highlight that "*by introducing an anthropology of luminosity; an examination of how light is used socially to illuminate places, people and things, and hence affect the experiences and materiality of these, in culturally specific ways.*" From a phenomenological point of view, Merleau-Ponty [21] argues that "*we do not so much see light as we see in it*."

Further research is needed to carry out wider measurements of illuminance as experienced and perceived by building users, combining real time measurements with recordings of users' space use and reactions during a whole bathing session in a working rehabilitated heritage hammam.

This paper opens up new avenues for further research based on the innovative combination of historical, architectural, building science research and environmental psychology methodologies to reveal tacit rules underlying the luminous environment of heritage buildings, as well as their perceived experimental qualities, in order to provide benchmarks for the rehabilitation of original luminous environment and their reinterpretation in contemporary designs.

**Funding:** The architectural survey part of the research on the public baths in Marrakech was funded by the Arts and Humanities Research Council (AHRC) as part of the UK gran<sup>t</sup> number [AH/D503019/1].

**Acknowledgments:** The author would like to thank Khadija Kadiri, the manager of Hammam Rjafalla, for providing me with the opportunity to retrofit the vernacular daylighting system in her hammam, install data loggers and carry out measurements and interviews during the summer months of 2016. Sincere thanks to Mr Hadj Youssef, president of the hammam managers association of Marrakech and to all the hammam managers of Marrakech for allowing me to complete the roof surveys.

**Conflicts of Interest:** The author declare no conflicts of interest.
