This design for the Cheongna City Tower is based on creating an innovative spatial, structural, and energy production device which will become an operational symbol of the future for the IFEZ Cheongna region. Located at the intersection of the main pedestrian passageway from east to west and the main artificial waterway from north to south in Lake Park, the Tower is intended to be a hub of urban activity and a new destination for the region. It is 400 M. tall and offers views of the ocean, the Incheon Airport to the west and Mt. Geyang to the east.
The lower levels of the Tower contain various leisure and cultural activities such as art and design exhibition spaces, an assembly and lecture space, gift shops, and bars. The mid-levels of the Tower contain public Sky-Terraces every 50 M. as well as a Business Spine which contains showroom office space for various technology companies and cultural institutions. The upper levels of the Tower contain an astronomical observatory, a seasonal high-end restaurant with
star chefs, and various lookout points and observation decks.
THE VERTICAL WINTERGARDEN AS ENERGY DEVICE
The envelope of the Tower is based on a double-shell construction which creates a Vertical Wintergarden. It houses various observation decks, botanical gardens, and leisure activities. At night it glows in changing color and light, visible from landing aircraft as well as the surrounding territories.
This Vertical Wintergarden is a naturally ventilated buffer zone isolated with ETFE foil on the exterior. It operates as a greenhouse in the winter, collecting heat energy to be circulated throughout the building and as a thermal insulator in the summer, protecting the internal spaces from thermal gain. Rising hot air in the space accumulates at the top where it is passed through heat exchangers and micro-turbines which recoup the energy before the air is exhausted.
In addition, the Wintergarden is used in summer as a storage device for cool air which is collected at the top of the tower through large wind intakes which are opened during the night. This is based on the model of passive nighttime cooling towers literalized at a mega-scale. Finally, a reversible hydronic system is integrated into the exoskeleton of the building which provides radiant heating and cooling. It is supplied with cooler or warmer fluids from geothermal source heat pumps but it also utilizes the available cool water from the lake basin on site when possible.
THE PLAZA AND THE ROOF
The typology of vertical tower and horizontal plinth is a classic architectural problem. Since the birth of the high-rise, there have been many approaches– both utopian and opportunistic– to resolving how towers connect to the ground as well as to horizontal buildings. This proposal biases continuity between the Tower and its horizontal extensions in order to create a fluid and protected space beneath. These extensions adapt to perform three different functions: ferry platform to the east, retail building to the north, and Plaza Roof to the south.
The Plaza is characterized by urban and natural topography, including lush vegetation and exotic flowers, a network of waterways and pools, and hardscape terraces. Interspersed are cafes, restaurants, cultural events, and the attendant amenities. The space becomes a complex, lively urban space where visitors can relax, meet friends, and engage in leisure activities. It is both a sanctuary and a vibrant urban atmosphere.
The structure of the Tower is based on a steel exoskeleton rather than a traditional structural core model. Three main structural spines weave along the facades, varying in terms of depth, width, and rotation in response to vertical and
ateral forces as well as geometrical rules set by the design team. Similar to the inside of a turtle’s shell, these spines are merged together to form a hybrid of monocoque and frame-and-skin construction types. The structural morphology becomes that of smooth gradients between surface, surface relief, and strand which is a continuing interest of EMERGENT.
CATIA, modeFRONTIER, and ROBOT
A combination of parametric software, population generating software, and structural analysis engines was used in a bottom-up nonlinear engineering process. This process is similar to natural selection in nature where populations of mutations are generated and then fitness tested by environmental forces. Successful solutions are then bred and tested until the search eventually narrows.
CATIA was used to set up the geometry within parametric constraints, allowing for a particular range of behavior. ModeFRONTIER was then used to generate populations of mutations based on a stochastic, non-linear method. These mutations were then processed automatically through ROBOT which performs a basic structural evaluation of the mutations, which were then evaluated for their architectural potential. The ‘survivors’ were then propagated into a new generation in modeFrontier and so on, establishing a feedback loop.
The key here was a multi-objective optimization process, which does not have the goal of 100% optimum in any single search but rather a more ecological approach of multiple individual tendencies producing complex, emergent tendencies at higher levels of organization. For this project three boundary conditions were used:
I. Spine Buckling Response (Rotation)
II. Spine Bending Response (Depth) III. Spine Footing Response (Translation) This way of working redefines engineering workflows and potentially, the roles of architect and engineer in the design process. The danger here– something we are consciously avoiding– is an anemic understanding of optimization as a reductive quest for efficiency rather than as a generative design process which can result in architectural ‘species’ characterized by both efficiencies and excesses.