Renovation of Shizukanaoka Park Indoor Pool with Membrane Roof

Taiyo Kogyo Corporation (Head Office: Setagaya-ku, Tokyo; Osaka Head Office: Yodogawa-ku, Osaka; President and CEO: Yuuki Nōmura), a leading manufacturer of large-scale membrane structures (tent structures), civil engineering, and logistics materials, has completed the renovation of the indoor pool at Shizukanaoka Park (Yokohama City, Kanagawa Prefecture), which is scheduled to reopen on July 21, 2026. The company was responsible for replacing the existing glass roof with a membrane roof.

To address the issue of rising indoor temperatures during summer caused by the previous glass roof, the project adopted a highly translucent and solar-reflective membrane roof. This solution maintains a bright interior while effectively suppressing temperature increases, significantly improving user comfort.

Shizukanaoka Park Indoor Pool with a membrane roof that allows natural light while reducing heat buildup

Replacing glass roof with membrane roof to suppress summer heat

The indoor pool at Shizukanaoka Park was originally constructed as part of the 60th anniversary commemoration project of Emperor Showa’s reign. Its glass roof created a bright and open atmosphere, a defining feature of the facility. However, during summer months, solar radiation caused significant indoor temperature increases, posing a challenge for maintaining a comfortable environment.

The new membrane roof has a high solar reflectance, efficiently reflecting solar energy—including heat—thereby minimizing heat absorption into the building. This effectively suppresses indoor temperature rise during summer, contributing to a more comfortable user experience and extending the facility’s usable period throughout the year.

Additionally, the white membrane’s translucency allows ample natural light to enter, creating a bright and open space. This reduces the need for artificial lighting during daytime, contributing to lower maintenance and operational costs.

*1 Taiyo Kogyo website: Features of Membrane Structures https://www.taiyokogyo.co.jp/membrane_features/

Advantages of lightweight and flexible membrane materials

Membrane materials are extremely lightweight compared to conventional roofing materials, significantly reducing structural load on the building frame.

Their flexibility allows them to move with seismic vibrations during earthquakes, making them less prone to damage and eliminating the risk of flying debris. This reduces the likelihood of secondary disasters caused by falling materials, enhancing overall safety.

Durability suitable for pool environments

Membrane materials are highly resistant to corrosion caused by chlorine and water vapor, making them ideal for pool facilities.

The selected material, PTFE-coated ethylene tetrafluoride resin membrane (PTFE membrane)*2, also features excellent anti-soiling properties. A titanium dioxide photocatalyst coating*3 on the surface breaks down organic dirt, which is then washed away by rainwater, enabling the roof to maintain its white appearance over the long term.

*2 PTFE-coated membrane: A durable composite material made of glass fiber fabric coated with fluororesin, first used in the world’s first permanent membrane structure—the Laverne University Sports Science & Athletic Pavilion (1973, California, USA). It has been in use for over 50 years.

*3 Titanium dioxide photocatalyst: Reacts with sunlight (UV rays) to oxidize and decompose organic matter. The decomposed dirt is washed away by rain, providing a self-cleaning effect. Furthermore, fluororesin-based titanium dioxide photocatalytic membranes break down NOx (nitrogen oxides), converting them into harmless ions, thus contributing to air purification.

Efficient renovation using lightweight membrane materials

As a renovation of an existing facility, the project faced constraints on the use of heavy machinery and material transportation. The lightweight and highly portable nature of membrane materials enabled efficient construction even under these challenging conditions.

Preservation of architectural aesthetics

The facility has long been a local landmark, with interior lighting softly glowing through the glass roof at night. The new membrane roof maintains this visual identity by softly diffusing light, preserving the facility’s iconic nighttime appearance without compromising its design integrity.

Exterior appearance of the membrane roof: bright during the day, softly diffusing light at night

Overview of Shizukanaoka Park Indoor Pool

Address: 87-2 Shizukanaoka, Minami-ku, Yokohama City, Kanagawa Prefecture 232-0007

Facilities: - Main Pool: 25m × 13m, depth 1.1–1.2m - Children’s Pool: 13m × 5.5m, depth 0.8–0.9m - Toddler Pool: Oval, 22㎡, depth 0.36m

Membrane Roof Overview

Client: Yokohama City Green Environment Bureau Design: Kuni Sekkei Co., Ltd. Construction: Kikushima Co., Ltd. Membrane Work Period: July 2025 – February 2026 Taiyo Kogyo’s Scope: Manufacturing and installation of membrane and secondary steel frames Membrane Material: AP450 Membrane Surface Area: 1,328㎡

About Taiyo Kogyo Corporation https://www.taiyokogyo.co.jp/

Taiyo Kogyo Corporation is a leading company in large-scale membrane structures with over 100 years of history. At Expo ’70 in Japan, it achieved the world’s first low-rise air-inflated membrane structure for the U.S. Pavilion, supported solely by air pressure. Since then, the company has participated in major global projects, including the roof installation of the Tokyo Dome and the world’s largest dome structure, the Millennium Dome in London (now The O2 Arena). It also contributed to over 20 pavilions and facilities for the 2025 Osaka-Kansai Expo, supporting the development of the expo site. Leveraging its membrane technology—renowned for economic efficiency, constructability, translucency, and design flexibility—the company operates across architecture (sports and transportation facilities), civil engineering, logistics, disaster prevention, and environmental sectors, contributing to societal safety and security.

Together with group companies such as TSP Taiyo Corporation (event consulting) and Actio Corporation (facility management), Taiyo Kogyo promotes the vision “Softening the World. Warming the Future.” to deliver new value to society.