Building on a Classic Legacy: An Invisible Extension.
Our fundamental concept — which evolved gradually as our design for the new extension developed — was to respect and to create a dialogue between two existing but contrasting elements: Jean Tschumi’s original creation and the wide, open green spaces of its setting. A masterpiece of modern architecture, Tschumi’s design — now 50 years old, and weathering beautifully — has three distinct elements: a linear office block hovering above the access level and a spiral pavilion structure that connects downwards to a lower volume, which orders and defines the limits of the ensemble.
We wanted to create a design that would not challenge Tschumi’s concept — by being too large or too close — and so would have an ‘invisible’ impact: increasing the client’s usable room space, but adhering to the current site curtilage. It would provide fine, functional, and flexible spaces in which people could work and gather, concentrate and relax, that were easily accessible and naturally lit, but would both embrace and integrate the whole campus and open it out to the local parkland.
The principal element of our proposal is a single, new, L–shaped horizontal volume whose two wings define the site’s edges. Its restrained scale facilitates uninterrupted views of the surrounding landscape from the existing offices, and its ‘invisible’ green roof — turfed with grass and shrubs — creates a terrace garden whose edges seem carved into the landscape, drawing nature into the site. Extending outwards, it serves as a walkway into the panorama, giving clean views back to the main building.
In the wider context, this roof/terrace garden connects the site seamlessly to the neighborhood’s disparate elements — the proposed forecourt esplanade north of the existing building and the parkland south of the site. A discreet ramp on its western edge gives vertical circulation to the offices below and to Appia Parkway, while a bridge links to the park, creating generous public spaces that accommodate bicycle and pedestrian paths.
Nestled into the park’s gently sloping landscape, the new additions adopt the scale of the ensemble’s existing buildings, and the structural rhythm of the office volumes complement the existing spiral pavilion structure. Buildings, topography, and landscape are held in harmony, erasing the site’s boundaries and achieving a fluid transition from built spaces to landscape, which allows both to be experienced together.
The programme’s various requirements are accommodated in an inconspicuous two-storied volume under the green roof. The main linear block provides individual and open offices while a connecting block contains shared facilities: a restaurant, meeting rooms, a conference hall, a strategic operation center at the lower level, and offices at the first-level. Between them, these two new volumes define a central courtyard, linking the existing spiral pavilion to the new extension. A multi-purpose exhibition and reception area at the lower level connects the main building to the new extension while serving as a meeting point for users of the building. The car park is on the underground level.
The office spaces are organized in a simple and rational manner. Multiple individual interior offices are arrayed along the periphery of the proposed extension and is designed to harvest natural light while a central bay houses open-plan offices and open-to-sky courts in a configuration that can easily be adapted to future needs. The modest exposed concrete finishes deliberately downplay the visual impact of the new additions, striking a pleasing contrast with the main building’s glass-and-aluminum façade.
The layout is rooted in the principle of equity, providing all users with excellent work conditions, including natural light and views of the surrounding landscape. The primary room module sizes and configurations follow the proportions of Tschumi’s original main building design.
The open core of the ensemble functions as a courtyard from where staff and visitors can experience the contrast in scale between the old and new architectures. It offers both sun and shade and gives direct access to the new extension: a single-storied volume houses a restaurant and creates a transition space overlooking and opening into the courtyard.
The large conference facility is set at the corner where the two new lateral volumes meet, its contrasting design emphasizing its prominence and functional autonomy. It can be subdivided into four smaller areas according to ‘golden ratio’ principles, and its size, location, and sky-lit roof echo the pyramid-shaped structure of Tschumi’s initial studies.
The green roof’s biodiversity reduces heat loss and allows for rainwater recapture and filtration. The landscaping respects existing trees and resettles local species, while the interior patios feature species from the six continents, symbolically portraying the WHO’s international function.
The proposed new extension marks a fresh stage in the development of this important site. It offers considerably enhanced working and public spaces, enshrines today’s eco-imperatives, and opens the site up to landscape and light while still paying tribute to Tschumi’s legacy.