EXPO Osaka 2025 Sauna 'TAIYO TSUBOMI' / KOMPAS

Architects:KOMPAS

Area:161m²

Year:2025

Photographs:Yohei Sasakura

Category:Pavilion,Sauna

Organizer:Japan Association for the 2025 World Exposition

Owner / Design Client:Taiyo Kogyo Corp.

Sauna:TTNE Inc.

Landscape Designer:SORA BOTANICAL GARDEN Project Inc.

Lighting Designers:REALROCKDESIGN Inc.

Sound:KISSonix, Inc.

Construction:TSP Taiyo Inc., Taiyo Kogyo Corp.

City:Osaka

Country:Japan

Text description provided by the architects. Situated along the western seafront of the EXPO site, "TAIYO TSUBOMI" (Bud of the Sun) is an experimental sauna complex embodying the concept of "resonance with nature" and the "awakening of synesthesia". It invites visitors to the new immersive experience with nature through its architecture, atmosphere, and unique sauna rituals.

Set on an open platform surrounded by greenery, three distinct membrane volumes emerge: a sauna that wraps in heat like a bud, a comfort lounge bathed in light and wind, and a cold bath under the balloon roof. These units engage in resonant dialogue with nature, swaying in the breeze, reflecting the sky, and glowing in sunset hues, which creates a rich sauna experience in harmony with the lush greenery.

Guided by a sauna attendant, participants embark on a curated journey of "11 Sauna Rituals," blending immersive narrative and sequential steps with sensory stimulation —light, sound, scent, and heat—that transcends the conventional sauna experience.

This innovative membrane architecture is formed by tetrahedral air-membrane units constructed solely from thin aluminum frames, ETFE film, and air. This minimal structural framing encloses maximum air volume, providing remarkable stability and insulation while remaining lightweight, and reaching heights of up to 8m. The modular ETFE system offers versatile adaptability and, when deflated, becomes compact, allowing for effortless relocation and reuse.

The ETFE membrane with a frosted texture diffuses light while embracing warmth in the sauna. Unlike traditional wooden finishes, the sauna interior is crafted entirely from translucent materials, capturing solar warmth by day and transforming into a luminous atmosphere by night. This soft, lightweight architecture fully exploits the ETFE membrane's resilience and translucency.

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