Sun Tower | OPEN Architecture

OPEN has revealed the design for its under-construction Sun Tower project on the coast of Yantai, a booming city on the coast of the Yellow Sea. Recipient of the Jeu d’Esprit Special Prize of AR Future Project Awards 2021, the Sun Tower comprises a semi-outdoor theatre on the ground, a winding exhibition space, and a library in the sky. The building also has a unique semi-outdoor space at the top, referred to as the “phenomena space”, designed for people to observe the magnificent natural phenomena throughout the year.

The name of the city of Yantai means “Beacon Tower” and was derived from the series of watchtowers built during the Ming dynasty as a warning against impending attacks on the coastline. The city wanted to create a landmark on the coast, its fast-developing new district, one of the earliest special economic zones in the country and an industrial powerhouse today. OPEN’s response to the design brief was to move towards a more purposeful structure, something that would evoke the ancient rituals of nature-worship while providing much-needed cultural facilities in the newly urbanised district. Yantai is also often noted for its beautiful views of sunrise across the Yellow Sea, something the architects would embrace in their design.

The form of the building is a large curvilinear structure; the structure’s shape is designed according to careful studies of the sunlight and appears sliced open by beams of light, revealing the interior spaces to the majestic sea. The 50-metre high structure sits inside a gently sloping plaza. The building is a composite shell structure, two layers of slanted white concrete shells are connected and braced by horizontal slabs and ramps. This complex design has been achieved through close collaboration with engineering firm Arup.

Facing the ocean, the concave inner shell of the Sun Tower acts as a sound collector, absorbing and amplifying the sounds from the sea. The smaller upside-down upper shell houses the light-filled library and the ‘phenomena space’ with a breathtaking view of the ocean and the sky above. An oculus in the centre of the phenomena space’s ceiling allows rainwater to enter and fill a small pool underneath in the summer. In the winter, the pool will be dry and used as a fireplace.

In the early design phase, working with French firm dUCKS scéno, OPEN conceived the exhibition spaces inside the building with a focus on digital exhibitions and big data technologies, while also simultaneously being an energising force for the long-term growth of this new city.

At the base of the tower, in the plaza also designed by OPEN, a shallow pool completes the circular shape and features misting devices and spouting fountains. A specially designed water channel cuts across the plaza—a ruler of time—this is the straight line that the shadow of the Sun Tower will follow on the day of the equinox. A series of elliptical rings are set in the pavement pattern; the intersections between the rings and the water channel mark the building shadow’s footprint at specific hours on the equinox day. At one of the outer rings, a series of fountains were designed to celebrate the 24 Solar Terms of the Traditional Chinese Calendar; on normal days they are synced with high and low tides. These carefully planned water features add to the sense of liveliness, while also reflecting upon the city’s long history of oceanic culture which is rare in China.

The project is expected to be open to the public in 2024 and will be featured in OPEN’s forthcoming book Reinventing Cultural Architecture: A Radical Vision by OPEN published by Rizzoli in April 2022.