Undulating Glass Panes

Picture: Couvent de la tourette façade ouest – © Famille I Xenakis

Elisavet Kiourtsoglou

Undulating glass panes consist in an assemblage of glass panes of various lengths; they were used for the first time for the Monastery of Sainte Marie de la Tourette (1953-1961). The project was assigned to Le Corbusier (1889-1967) by the Dominican Friars’ Community of Lyon, in an attempt to modernize the architecture of worship places. The building contains hundreds of cells and everyday living spaces for the friars, as well as a church open to the public. Inspired by the Thoronet abbey (12th century), Le Corbusier designed a massive concrete rectangle containing an inside yard. The placement of the openings was carefully thought out, to canalize and uplift the gaze as well as to offer points of contemplation – the main spiritual practice of Dominican friars. Le Corbusier oversaw the overall design, while Xenakis was named chief architect of the project in charge of the building’s construction. Nevertheless, the young architect had managed to obtain significant liberties pertaining to various design questions, including the type and form of the openings. To Xenakis has been attributed the design of the light canons, illuminating the monastery’s crypt, as well as of the mitraillaitte (machine gun) openings, shining direct light into the sacristy only twice a year, during the equinoxes. But, without doubt, Xenakis is mostly known for the “musical” or “undulating” glass panes, covering various façades of the monastery; this was the first instance when Xenakis employed elements of his music research in his architectural practice.

In 1954 Xenakis was looking for a solution for the openings of the circulation corridors, surrounding the yard. His first attempt was to combine concrete and glass panes for these openings using principles of the serialist vocabulary. At the time, Xenakis had just finished the orchestral work Metastaseis (1953-54); recent research (Barthel-Calvet 2011) has shown that the work’s middle section makes use of mathematical permutations to alter various series of 4 preselected pitch-classes. The composer transferred this principle to the corridor’s openings design: he chose glass panes of four different lengths and permuted their position inside a predefined panel; that was repeated several times along the three façades looking at the internal yard.

The principle of permutation was approved by Le Corbusier and Xenakis tried to also use it for the external façades design. Choosing to permute glass panes of 10 different lengths instead of 4, proved to be rather inadequate. The elevated number of possible permutations of the preselected panes (around 3 million options) made Xenakis change his mind. The solution came again from his compositional practice. According to Xenakis, this same period he was exploring the possibility to build an electroacoustic work based in the variation of sound’s density (see Xenakis 1984). In a similar approach, he proposed to alter the variation of the density created by the arrangement of the glass panes on the external façades of the monastery. Not only the design material to be handled was less numerous, but the effect was also more interesting: clusters of high density (glass panes of very short length) were now alternating with clusters of low density (longer glass panes) creating various types of undulations. Moreover, on the west façade this alternation was performed in two directions simultaneously, horizontally and vertically across the four floors. New findings (Kiourtsoglou 2015) show that the alternation of these levels of density was defined according to another music concept, that of intensity. Using the music notation signs for dynamics (crescendo/decrescendo), Xenakis defined the levels of density of the glass panes by creating a “score” for the changes of density of the glass panes along the façades.

According to Xenakis (1984), the use of density and intensity in design methodology was also drawing attention to the question of transition, important in both music and architecture. The compositional art now focused on the way to transition from one element to another either by sharp differentiation or by slow melting into the next one, producing various transitional modes between the glass pane undulations. Xenakis’s next move was to split the overall façade length in smaller parts, whose lengths were chosen from golden-ratio scales. One such scale was the Modulor, invented by Le Corbusier to help harmonically build the architectural space. But this practice was already familiar to Xenakis: research shows (Baltensperger 1996; Barthel-Calvet 2000) that at around the same time he also split the time lengths of Metastaseis into smaller parts, where specific sound phenomena would take place (clusters of sound, glissandi, etc.), following the Fibonacci Series (1 1 2 3 5 8 13 and so on), which also relates to the golden ratio.

The whole approach was much appreciated by Le Corbusier, so Xenakis was instructed to focus on the “formalization” of this process. He produced a table with several possible variations of clusters (termed waves) including preselected glass panes whose length was decreasing or increasing in such a way so as to produce “ready-made” undulations. From then on, every designer or architect in Le Corbusier’s office could use one or more clusters of glass panes according to the overall length of a façade to be covered with such type of openings. Le Corbusier deposited Xenakis’s table, along with a text by him on the characteristics and benefits of these glass pane types, to the French bureau of patents. Due to their similarity with the undulation of elastic media, what was originally termed musical glass panes were to pass down in history as undulating glass panes. They have been used in many projects at Le Corbusier’s office, even after Xenakis’s departure in 1959, such as the Maison du Brésil in the Cité Universitaire de Paris and the Maison de la culture et de la jeunesse at Firminy. Xenakis also used the principle of undulating glass panes in his daughter’s house in Paris and in the family vacation house in Corsica.


Baltensperger, André. 1996. Iannis Xenakis, Komposition im Spannungsfeld der Architektur und Musik. Basel: Haupt Verlag.

Barthel-Calvet, Anne-Sylvie. 2000. “Le rythme dans l’œuvre et la pensée de Iannis Xenakis.” PhD diss. EHESS, Paris.

Barthel-Calvet, Anne-Sylvie. 2011. “Xenakis et le Sérialisme: L’apport d’une analyse génétique de Metastasis.” Intersections: Canadian Journal of Music / Intersections: revue canadienne de musique 31 (2): 3-21.

Kiourtsoglou, Elisavet. 2015. “Le mystère des pans de verre ondulatoires de la Tourette de Le Corbusier et Xenakis.” Intersections: Canadian Journal of Music / Intersections: revue canadienne de musique 35 (2): 75-118.

How to cite

KIOURTSOGLOU, Elisavet. 2023. “Undulating Glass Panes.” In A Xenakis Dictionary, edited by Dimitris Exarchos. Association Les Amis de Xenakis.