CSWADI Wraps a Chengdu Fusion Research Center Around a Funnel-Shaped Sichuan Light Well

Buildings for nuclear research usually go one of two ways: they hide behind security fencing as anonymous sheds, or they reach for science-fiction imagery and date within a decade. The Tianfu Fusion Technology Research Center, designed by CSWADI (China Southwest Architectural Design and Research Institute) for the Southwest Institute of Physics of China National Nuclear Corporation, tries a third route. It is a 38,000 m² ring of offices and laboratories in Chengdu's Tianfu New Area, set beside an artificial lake. Its whole interior bends toward a single planted void capped by a tapering membrane funnel.

The interesting part is not the circle itself. Round buildings are easy to draw and hard to justify. What is interesting is the pairing of references. The design team, led by chief designer Liu Yi, draws on the physics of controlled fusion and on the tianjing, the light well at the heart of the traditional Sichuan courtyard house. The result reads as a toroidal reactor from the drone and as a courtyard house from the inside. We think that double reading mostly works, and it is worth looking at where it is strongest and where the symbolism gets ahead of the architecture.

A Ring Set into the Tianfu Landscape

From above, the parti could not be clearer. A thick, layered ring sits on a green base, its centre punched open by a funnel. A smaller round canteen pavilion sits across a dark reflecting pool, and curving paths ring both volumes. The site covers about 8.9 hectares, and this is only phase one of a phased master plan. That explains why the landscape feels deliberately open-ended: the circles in the paths and planting are setting up a grammar that future buildings will have to answer to.

At eye level the ring becomes a long, low oval of silver horizontal bands. Seen against the forested hills and hazy ridge, it is calmer than the aerials suggest. The banding keeps the mass horizontal and stops a 38,000 m² building from looming over the plaza. That restraint matters on a campus that will keep growing around it.

The Roof as Light Well and Energy Plant

The roof does the most conceptual work. A funnel-shaped glazed and membrane skylight drops into the atrium, and a continuous ring of photovoltaic panels surrounds it on the upper surface. In a traditional Sichuan house the tianjing pulls light, rain and air down into the dwelling. Here the same gesture is scaled up and inverted into a cone, so daylight is collected over a wide opening and concentrated into the void below.

Seen from inside, the funnel hangs above a conical glass volume like a lens over a target. It is the clearest moment where the fusion metaphor and the vernacular reference line up: energy and light gathered from a broad field and focused at the centre. The solar ring keeps the idea from staying purely symbolic, although the sources we reviewed do not say how much of the building's load it covers.

Inside the Atrium

The atrium is where the project earns its scale. Tiered, curving balconies stack up one side, white conical volumes and a glazed hourglass core occupy the floor, and a planted garden runs underneath a ribbed white vault. At dusk the garden is lit from below and the whole space reads as a covered courtyard rather than a corporate lobby.

The risk with a void this large is that it becomes a showpiece the occupants walk past. The white spiral stair and the balconies help here. They turn vertical circulation into a visible social route, so researchers moving between floors pass through the same light that defines the building. For a research institute, where chance encounters between teams can matter as much as the labs, that is a useful choice.

Cable-Net Glass and Translucent Canopies

CSWADI brought in a dedicated curtain wall team, and you can see why. The inner face of the atrium is a cable-net glass enclosure held by steel clamp nodes, with a curved translucent canopy above. Close up, the bolted clamps and bracing cables are left exposed. The building shows its tension structure instead of hiding it, which suits an institution whose work is about containing enormous forces with precise engineering.

At the entrance, two translucent white cones on angled steel struts stand over shallow water basins. They are the most literal objects in the scheme, small reactor-like vessels that announce the program. Inside, perforated metal screens and diagonal ribs throw shifting patterns over a terrace. That detail does more for the experience of the place than the cones, because it turns sunlight into something you notice through the day.

Louvred Bands on the Outer Ring

The outer facade is built from stacked horizontal bands of glass louvres and ribbon windows that follow the curve without interruption. Looking up, the tiers read as rings in a coil. That is the fusion imagery handled with more subtlety than the cones, because it emerges from a practical device: louvres that filter sun and give the office floors a continuous outlook.

The balconies make the facade habitable. Timber decking, louvred glass screens and a steel railing give staff a place to step out over the trees. At ground level, a long reflecting pool runs along the glazed base and a thin white canopy on V-shaped columns marks the edge. The water doubles the banding at dusk and softens a facade that could otherwise feel mechanical.

Water Between Laboratory and Canteen

The artificial lake connects the main research building and the staff canteen, and it is the best landscape decision on the site. Instead of a corridor or a forecourt, the two programs face each other across still water. From inside the offices, the round, layered canteen pavilion sits on the far side of the pool like a smaller planet in orbit.

The round glass stair pavilion with its thin white roof disc, set on a green terrace, extends the circular motif into a building small enough to read at human scale. It is a reminder that circles do not have to be monumental to be legible.

Offices and Meeting Rooms

The workplace floors are quieter than the atrium, which is how it should be. Open offices with round white columns and grey carpet look out through full-height glazing to trees. The ring plan keeps every desk close to either the outer facade or the inner courtyard, so the depth problem of large office plates largely disappears.

In the meeting room, concentric oval ceiling rings and slanted white struts carry the geometry indoors. It is a lot of motif for a room built around a U-shaped table, and here the circle starts to feel applied. Where the inner glazing opens onto the courtyard garden, with its stepping stones and an autumn maple, the building is at its most convincing: light well first, physics metaphor second.

Plans and Drawings

The plans confirm how disciplined the scheme is. The ground floor wraps a central garden and links by corridor to the round canteen. The upper floors form a ring of open offices and meeting rooms around the void, joined by a bridge to the smaller volume. The basement puts parking and service rooms around a central multifunction hall, with a kitchen wing serving the canteen. A services diagram shows color-coded routes radiating across the ring of floor beams, which suggests the radial geometry was coordinated with MEP from the start rather than imposed afterward.

The sections are the most revealing drawings. One shows blue airflow arrows and a sun ray passing through the hollow atrium, which points to an intent to use the void for daylight and air movement. Another shows the lattice shell of the atrium over the stacked office floors. The cutaway axonometric ties it together: a tapering ETFE membrane roof, a truss ring and a planted atrium at the core of the building.

Why This Project Matters

China is building a lot of large state research campuses, and most of them default to either corporate glass blocks or iconic gestures with little spatial consequence. This one shows that a scientific metaphor can organize real decisions about light, circulation and services when it is paired with a building type people already understand. The tianjing gives the fusion imagery a body. Without it, the circles would be branding.

It is not flawless. The entrance cones and some interior ceilings lean on literal symbolism, and we would like to see performance data on the solar ring and the atrium's environmental role before calling it an exemplary low-energy building. Still, the core move is strong: a working ring of offices turned inward toward a planted, daylit void, with a lake that makes lunch a short walk across the water. As the master plan grows, that central courtyard will be the standard the rest of the campus has to meet.

Tianfu Fusion Technology Research Center, Southwest Institute of Physics (SWIP). Architect: CSWADI (China Southwest Architectural Design and Research Institute); chief designer Liu Yi, deputy chief designers Ma Jun and Feng Ting. Location: Tianfu New Area, Chengdu, China. Area: 38,000 m². Year: 2026. Photography: Arch-Exist.

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