null²　-Design Process- null²

For the Signature Pavilion “null²” at the Expo 2025 Osaka, Kansai, NOIZ was responsible for the schematic design commissioned by the Japan Association for the 2025 World Exposition, as well as the construction documentation and site supervision under the general contractors Fujita Corporation and Daiwa Lease. Under the overarching creative direction of Producer Yoichi Ochiai—who envisioned a pavilion that is metallic yet behaves like a flowing, slippery liquid—NOIZ, Arup, and other association-appointed design teams were joined by additional specialist groups working on kinetic mechanisms, LED vision systems, and AI, forming a multidisciplinary structure to develop the exhibition and interior–exterior environmental effects. Design work began in February 2020.

The initial concept proposed a two-story, circulation-based exhibition facility with a central tower, combined with an operable metal-panel façade. However, amid various evolving conditions, the budget underwent significant reductions. In response, NOIZ proposed in the summer of 2021 to use a mirror membrane for the outer shell, and by mid-2022 the project had been scaled down to nearly its current scope.

Because the pavilion needed to reconcile many conflicting demands—metallic hardness and liquid fluidity, static tension and dynamic transformation, complex composition and cost constraints—NOIZ initiated development of a new mirror membrane material from a very early stage. In August 2021, Taiyo Kogyo was invited to join the project to develop a new type of reflective membrane. Achieving metallic gloss and tactility through membrane fabrication required more than two years of experimentation and testing, ultimately resulting in an ideal material with a reflectivity of 98%. While evaluating functional requirements such as area, scale, roof access, and internal circulation, the team gradually developed exterior design options aligned with feasible structures and volumes. In November 2021, NOIZ presented four proposals to Producer Ochiai:

1. Bubble,

2. Voxel,

3. Slime Mold, and

4. Tube.
   At that time, the project still assumed a two-story structure with rooftop access.

The Bubble proposal envisioned a cluster of spherical forms constructed as pneumatic membranes. Combining compressed air with helium would create a lightweight and symbolic structure, but the scheme was abandoned due to rising helium prices, the need to maintain air pressure, and the inevitable requirement for additional wind-resistant structural systems.

The Voxel proposal, which ultimately became the basis for the current scheme, offered strong alignment with the project concept while also providing flexibility to accommodate major budget cuts and design changes. In terms of accepting compositional variability, it was the scheme that most directly inherited the Metabolist ideology of the 1970 Osaka Expo.

The Slime Mold proposal drew inspiration from the fruiting bodies of slime molds and the structural logic of coral. Exhibition spaces circulated between tower-like units, each constructed from metal plates and containing a mirrored sphere within its upper volume. By reflecting outdoor light through reaction–diffusion pattern surfaces, the scheme sought to transform rooftop LED lighting and the shifting colors of the sky into an experience that was both organic and digitally expressive.

The Tube proposal explored bundling mirror membranes into tubular pneumatic structures, introducing complex reflection and distortion effects. While referencing the air-tube roof structure of the 1970 Fuji Group Pavilion, the geometric and fabrication complexity made its feasibility low, and the concept was ultimately set aside.

In the post-pandemic era, when digital environments like Minecraft became a widely shared cultural experience, the pavilion adopted the voxel as its fundamental unit—an element common to both virtual and physical worlds. By rigorously employing simple cubic combinations—1 m, 2 m, 4 m, and 8 m, all binary multiples—the design emphasized the clarity of digital geometry while maximizing the distortion effects of inserted curved surfaces that warp perception and space. The paintings of Chuck Close served as a key reference: their use of grids, organic shapes, bold color variation, and boundary-crossing configurations that express sheen and fluidity were reinterpreted into architectural volumetric compositions.

Due to the constraints of tensegrity behavior and the cubic frame, curved-surface units were limited to two types: horn-shaped and saddle-shaped geometries. Maintaining geometric purity while resolving membrane behavior and construction requirements involved extensive collaboration with Arup and Taiyo Kogyo, with particular attention paid to continuity of curvature. With budget limitations requiring the number of curved units to remain minimal, these units were heavily concentrated on the west elevation—the effective “front” of the pavilion—to create an overall impression of organic dynamism, while other areas were intentionally kept static. From the outset, the pavilion assumed the integration of kinetic mechanisms, including robotic arms manipulating the membrane. During design development, a system to generate wave patterns using woofers was added as another dynamic element. Placement of horn and saddle units, robotic arms, and woofer components was continually refined through full-team discussions in order to maximize the architectural and perceptual dynamism. Every detail—from aluminum extrusion profiles and joint widths to hidden door assemblies and membrane deposition seams—was meticulously designed to intentionally reduce the sense of materiality.

null² ultimately functions as a device that integrates the real and the virtual. In addition to active elements such as kinetic mechanisms and LED imagery, it incorporates passive phenomena—reflection, surface distortion, changes in viewing position, and variations in weather—as dynamic components. Architecture that synthesizes dynamic information ceases to be a static environment and begins to acquire agent-like qualities. In the case of null², these agent qualities are further emphasized by the incorporation of “eyes” and a “voice,” giving the pavilion a perceptual agency as well as functional agency. Such agent-based architecture becomes an actor that both performs and receives, actively engaging human behavior and perception and expanding the possibilities of architecture as an environment.