Revisiting the spiralling, timber-ensconced hive, The Exchange by Kengo Kuma

Renowned Japanese architectural firm Kengo Kuma & Associates' celebrated oeuvre of works strikes chords in true material manifestation and artisan sensibilities, in particular, of choreographing timber into forms incredible. For instance, their spiralling, dynamic building wrapped in ribbons of wood, The Exchange in Sydney, is a porous piece of architecture built as a paean to geometry and sustainability. The visually powerful 'nest' is easily one of their most recognisable works, spontaneous, robust and beautiful in its cylindrical, radiating and expressive being. The almost lyrical arrangement of 20,000 metres of fair wooden ribbons (sustainably sourced acetylated radiata pine) encircling the concrete community centre seemingly at the random filter in natural light and provides a soft, attractive consistency to its interiors that resemble a silkworm's cocoon. The spirals extend leisurely into the public square outside, morphing into a perforated pergola that provides shade to those to pass or rest under it.

The mixed-used civic building (2015-2019), essentially a planned "exchange" with the city and its people, is located in the heart of the large urban development in the active area of Darling Harbor in Sydney, comprising a public library, childcare, and commercial uses, including a fresh food market and restaurants. Accessible and discernable from multiple directions, the Australian architecture is placed in harmony with the urban landscape and the nature that surrounds it, contrasting the dense skylines of high-rises and residential blocks with its playful vibrancy. The lively skin of numerous skillfully overlapping and overarching lumber bands wrap around the seven-storey shifting floor plates of The Exchange, also a historic reference to the Darling Harbour originally being a hive of business activity and a focal point of market exchange.

STIR revisits the much-beloved structure through the eyes of Yuki Ikeguchi, Partner, Kengo Kuma & Associates, as a throwback on the inner dynamics and generated social culture of their first completed project in Australia.

Jincy Iype: Against the rigid geometries of high rises and residential blocks, The Exchange, with its idiosyncratic, spiralling form encircled in bent wooden "threads" brings comfort to the site – what led to this?

Yuki Ikeguchi: The site given for our project was a “small pocket” among high-rise buildings done in hard surfaces within the large development plan. My immediate response in designing The Exchange was to generate an architecture that softens the surroundings.

The design approach, therefore, came about by creating an architectural form that harmonises with the square, to become a part of the urban landscape, narrating and integrating a human scale aided by natural materials, to offer a tangibly comfortable and dynamic building to the busy city. The circular geometry was chosen to amalgamate the built into the existing landscape, and to achieve an edgeless, convivial presence that draws in people from all directions, in a spontaneous manner. Warm timber ribbons outline The Exchange to echo the trees and to bring comfort to the interior as well as to the exterior of the concrete and glass form. Determinately, it was about forming a relationship with the people and the city through architecture, one that grows and builds organically.

Jincy: Please elaborate on the concept adopted for The Exchange. What would you say is the crux of its animated architecture?

Yuki: There was no singular concept that underscores the building, but to encapsulate, I would say it was to inject the urban square with a dynamic and exciting building that is respectful and employs natural materials. Wooden strips wrap the entire building in a capering spiral, while its tail continues out into the square to function as exterior seating and shelter for a gathering space. I am quite happy about the outcome and how it has become part of the city's existence, how the timber was composed, overlapping so that the joints would be concealed, resulting in a dynamic and playful character that works in unity with the open active square. The irregularity of the patterned timber stripes reveals an intended organic feeling as if we are set inside a "nest" or a cocoon, streams of sunlight streaming in from the gaps between them. The pattern and the placement of these wooden tapes were carefully studied for each floor, their subsequent orientation and their uses, so that they could serve as an effective screen for sun and privacy protection.

Jincy: What is the one unique feature of the mixed-use building that may not have been perceived as envisioned by you?

Yuki: The building includes multiple and layered programs that had different requirements according to varying functions, exposure and planning needs. I would say that the shifting floor plates at each level may seem playfully random but were done in a very controlled, planned manner, but may have been perceived as being done at a whim. Surrounded by residential blocks, retail at the lower levels, and an active flow of people along the boulevard, the site is a nodal point. We, therefore, chose a non-directional architectural form so that it would be accessible and recognisable from all directions, as an instant landmark architecture of sorts. The circular form reflects and promotes the vibrant and active neighbourhood of the Darling Square Precinct with its diverse mix of users.

Jincy: “Natural materials always cause unforeseeable problems despite the most careful planning. They break and rot and split. Inconsistencies are both their charm and their drawback… If building with natural materials is to be saved, it must be accomplished with humility and hard work, not bombast and confrontation.” In the context of this work, how has this played out?

Yuki: The use of timber in any form imposes certain challenges. For The Exchange, our design decision to curve and bend the timber strips gave us an exciting challenge, to manufacture, engineer all the fixing details and make it compliant with fire regulations, and make it attractive when seen cohesively. Instead of pre-curved laminated timber, we automatically went for solid, acetylated radiata pine that met the necessary fire retardant rating and also ensured extended longevity and warranty. Despite its overall random pattern and primate appearance, the timber screen's composition was well programmed with a base grid pattern overlaid with diagonal stripes, designed and scripted, and used for production, manufacturing and installation purposes. The process of design, patterning, detailing, and engineering was quite extensive.

Jincy: In continuation, can you relay to us the reasoning for employing timber for the structure? How was its delicacy achieved?

Yuki: Timber was selected for the envelope material to offer a natural, amicable texture to the building's neighbours. Timber stripes are composed of organic and spontaneous patterns that wrap around the shifting floor plates, overlapping with each other but almost never touching the facade actually. It acts as a screen to filter natural light and gives a soft texture to the interior space.

Jincy: What can you tell us about the shifting floor plates?

Yuki: The ground floor plane is conceived as an extension of the Square. A fully glazed façade enables the space to be open, transparent and accessible from all directions. It promotes interaction with the active street life and free flow of people offering opportunities for the community’s daily use. The middle levels of the building are dedicated for public use. To express the active and diverse nature of the building, a dynamic geometry was created through a shifting of floor plates. By shifting floor plates, comfortable and active outdoor terraces are created at each level that suits the use for its function.

Jincy: Your works are celebrated for their wise ability to unite architecture with nature and social responsibility – how was this manifested in The Exchange?

Yuki: It is our common approach to create architecture that is in harmony with its surroundings, with nature, with the locals, and consider biophilic design properly by incorporating natural elements as much as possible. Our process of generating the architectural form is perpetually in response to the surroundings and context. For The Exchange, what’s unique was the context being in the large-scale development, a bustling, busy space. The architectural and design response was not to merge with the surrounding buildings but on the contrary, to soften the context through the built form. Dynamism is injected into the playful, curved, low-rise building in an effort to extend it into its surroundings warmly. In the initial design phase of studying, research and design in the micro and macro scales are considered simultaneously, urban scale and human scale. On the urban scale, the building’s unique presence contributes to the surroundings, and on the human scale, it contributes to a warm, spirited and comfortable spatial experience.

Jincy: Over the years, how has The Exchange been experienced? Has it come close to your intentions when you built it?

Yuki: It is exciting to see how it has animated the dense, urban setting and has been functioning so well as a public facility. Over the years, the trees and greens in the square have grown mature and denser, enhancing the organic feel of the architecture. Together with the square, I believe it works quite well as a place to be and experience.

Jincy: What holds precedence – the materiality, or the impact of a project? Can a healthy balance between the two be achieved?

Yuki: I would say this project achieved a good balance between both. Otherwise, it depends on project to project.

Jincy: What is the most consistent aspect of your work?

Yuki: I believe all design processes initiate with a biophilic design approach, to apply as many natural materials and sustainable processes as possible; to create lives between buildings and people, to ensure quality open spaces between the newly implemented building and its surroundings; a simultaneous scale study of the micro-macro, to derive an architecture in response to the context and from tangible human scale. I believe this focus in the process forms robust, lively and informed architecture.

Project Details

Name: The Exchange
Location: Sydney, Australia
Area: 4,993 sqm (Site Area); 1,075 sqm (Building Footprint); 6,680 sqm (Total Floor Area)
Year of completion: 2019
Client, Structural Engineer, Builder, Developer, MEP and Architect of Record: Lendlease
Architect: Kengo Kuma & Associates: Kengo Kuma, Yuki Ikeguchi (Partner in Charge), Marc Moukarzel (Project Architect), Diego Martin, Mira Yung, Laura Sandoval Illera, Taylor Park
Landscape Architect: ASPECT Studios
Façade Engineer: ARUP, F&D Normoyle
Façade Optimization: ARMA