Kyoei Steel is Japan’s leading steel producer, specialising in recycling iron scrap. Using electric arc furnaces, the company transforms various types of scrap iron—construction waste like H-beams and rebar, cars, mobile phones, vending machines, even medical needles—into high-quality steel products for construction. This transformation of “once-used iron” into valuable steel forms the foundation of its business. Building on this expertise, Kyoei Steel has also advanced into environmental recycling, utilising cutting-edge technologies to render industrial waste harmless.

This project, located at Kyoei Steel’s Yamaguchi Division, replaces and consolidates aging office and welfare buildings, enhancing site efficiency. By centralising dispersed office functions into one structure, the new building improves productivity and provides a better working environment, while enriching welfare facilities, including dining halls and bathhouses, to enhance employee engagement.

The building’s exterior design was inspired by steel billets stored at the plant, visually symbolising the process of regenerating scrap iron into structural steel. It represents Kyoei Steel’s commitment to recycling, sustainability, and social contribution. The facade features five stacked billets with varied attributes, enhanced by two vertically divided stairwell volumes, forming a composition of seven billets. Each billet is distinguished by unique colours and textures, reflecting the diversity of the company’s product lineup.

Inside, steel products manufactured at the Yamaguchi Division—equal-angle steel, flat bars, and deformed bars—are prominently featured as finish materials, celebrating their raw strength and aesthetic potential. Materials like angle steel (L30x30, 50×50, 75×75), flat bars (FB-32, 50), I-bars (I-BAR-44, 75), and deformed bars (10φ, 25φ, 38φ) were used for walls, ceilings, and to form the company’s barcode pattern. From the entrance to the elevator hall, the space transitions vertically through the stairwell.

The stairwell features 93 wires (6φ) stretched across a 20-meter height, with five types of angles (L30x30 to L75x75) and seamless linear lighting installed along them. A QR code of the company’s website is integrated into the floor, and staircase handrails use randomly arranged angles and deformed steel bars (10φ, 29φ, 32φ). On the west side, similar steel bars cover the stairwell from floor to penthouse, interacting with handrails and lighting to emphasise verticality and continuity.

This interplay of light, shadow, and raw steel highlights Kyoei Steel’s technological strength and innovative spirit. Linear lighting and the western sun’s patterns create dynamic effects, intuitively conveying the company’s brand identity.

Through this design, Kyoei Steel’s philosophy of sustainability and social contribution is clearly expressed. By creatively showcasing materials and integrating corporate values, the project harmonises functionality and design. Rooted in the company’s recycling philosophy, it presents a prototype for future architecture merging sustainability, innovation, and identity, while offering a unique spatial experience that inspires visitors and reinforces environmental dedication.

Category:EnvironmentsAward Year:2025Location: Yamaguchi, JapanDesign Architects:Okumura CorporationArchitects:MR STUDIO Co., Ltd.Design Team:Masahiko Tokunaga and Tetsuya NagayoshiClient:Kyoei Steel Ltd.Photographers:Kenta Sato, JXPhoto Co., Ltd. and Nobuaki Miyashita, MR STUDIO Co.,Ltd.