The Arc At Green School / Ibuku

Architects: Ibuku
Area: 760 m²
Year: 2021
Photographs: Tommaso Riva, Courtesy of Ibuku
Structural Engineer: Atelier One, Atelier One, Neil Thomas
Creative Director: Elora Hardy
Design Concept: Ibuku, Jörg Stamm
Construction Manager & On-Site Architect: Ibuku, Jules de Laage
On-Site Consultant: James Wolf
Project Architect: Ibuku, Rowland Sauls
Build Time: 8 months
Width: 23,5 m (75 ft)
Length: 41 m (134 ft)
Height: 14 m (46 ft)
City: Kecamatan Abiansemal
Country: Indonesia

The Arc gymnasium, designed by Ibuku for Green School in Bali, features a unique bamboo roof structure with double-curved arches connected by gridshells. Created in collaboration with bamboo architect Jörg Stamm and engineering firm Atelier One, the 760-square-meter space offers a column-free sports court, with natural ventilation achieved through openings at the base and vents at the roof’s apex. Inspired by a ribcage structure, the gridshells create tension that stabilizes the arches while minimizing material use. This efficient, lightweight design reflects Green School’s sustainability ethos, where bamboo structures have defined the campus since 2008. Green School now also operates campuses globally, prioritizing natural materials and energy efficiency.

Architecture studio Ibuku has completed The Arc gymnasium for a private school in Bali, showcasing a complex, double-curved roof crafted entirely from bamboo. The Arc is the newest addition to Green School’s campus—a private educational institution focused on sustainability and learning within a natural setting.

The building was designed by Elora Hardy, daughter of Green School founders John and Cynthia Hardy, along with her studio Ibuku, in collaboration with bamboo architect Jörg Stamm and structural engineering firm Atelier One. It serves as a protective canopy for a 760-square-meter multipurpose sports court.

This lightweight structure incorporates bamboo arches supporting an organically contoured canopy. Standing 14 meters high, these arches are linked by anticlastic gridshells, which curve in two directions to form a robust, tensioned system. Ibuku project architect Rowland Sauls noted that “the concepted structure for The Arc is totally unprecedented,” adding that realizing a design of this kind required both “bravery and optimism” as well as the determination to innovate the solutions essential to the project’s success.

The building’s organic shape and structural design draw inspiration from natural systems, particularly the way ribcages are supported by the tension of surrounding muscles and skin. According to Stamm, “The Arc functions similarly to the ribs of a mammal’s chest,” stabilized by tensile membranes comparable to tendons and muscles between ribs. Stamm further explained that, “Biologically, these highly tensile microscopic tendons transfer forces from bone to bone.” In The Arc, this function is mirrored as bamboo splits transfer forces from one arch to another.

Months of research and development resulted in a precise geometrical design that enabled the structure to enclose a large internal volume with minimal materials. Atelier One director Neil Thomas explained that the gridshells utilize shape stiffness to form the roof enclosure, offering buckling resistance to the parabolic arches. Together, these systems create a uniquely efficient structure capable of flexing under load to redistribute weight, which helps to alleviate localized forces on the arches.

The pavilion’s roof arches span 19 meters, creating a spacious floor area free from supporting columns. Openings around the canopy’s base promote airflow, allowing breezes to circulate for natural ventilation, while vents at the roof’s apex enable warm air to escape efficiently.

Since its founding in 2008, the Green School has constructed bamboo buildings on its Bali, Indonesia campus. The school has since expanded to include campuses in New Zealand, South Africa, and Mexico. Every building at the jungle campus in Bali’s Badung regency is designed for energy efficiency and constructed with natural materials wherever feasible. John Hardy and Jörg Stamm collaborated with designer Aldo Landwehr to develop the initial buildings and infrastructure, which include bridges and a spiral three-story structure housing the high school and administrative spaces.