Qualitative and quantitative analysis of natural light in the dome of San Lorenzo, Turin

Abstract

The Church of San Lorenzo in Turin, which was designed by the Theatine architect Guarino Guarini in the 17^th century, is among the most famous Christian Baroque architectural masterpieces. Guarini was given freedom to plan and design this church, which can be considered his most innovative and influential work. The most significant feature of this building is its dome, which is magnificent and slightly different from what is expected from a Baroque church. The dome of San Lorenzo has been the subject of considerable research due to its perforated surface that allows daylight to penetrate into the interior space. However, this dome has been mostly described through mere observation in a poetic and mystical manner. Although a subjective analysis is vital in understanding this architectural piece, a systematic and objective analysis that includes numerical data is required to understand fully the illumination by natural light present in this work of architecture.

This paper presents a method based on high-dynamic-range-imaging luminance analysis that employs a quantitative luminous measurement technique to analyze the daylight behaviorin San Lorenzo. The first section of this paper investigates the subjective experience in the dome hall, and the last two sections objectively show the dome functions and the manner through which the design of Guarini creates various light values in different parts of the dome. Such a design is responsible for the unique experience in the dome hall.

Key words： Guarino Guarini; San Lorenzo; Baroque; Dome; Sacred light; HDRI