The Beacon of Seoul
640 m tall Seoul Light DMC Tower is a mixed-use project envisioned as a new model in sustainable super-tall building design. Located north of the Han River at the western edge of Seoul, Seoul Light DMC Tower rises as a gateway to the city. Greeting visitors as they approach from Incheon Airport and points west, the tower will create a first impression of Seoul’s identity as a global city of the future. Together with other future towers, Seoul Light DMC Tower sends a message about Korea’s standing in the world. The tower is particularly significant as it will be the first tower international visitors see on their way into Seoul. At 2100 feet (640 meters) tall, tower will be the tallest building in East Asia when it is complete in 2014.
Functi onal Program
Seoul Light DMC Tower project is a mixed-use development. The skyscraper of 133 stories offers approximately 447,365 square meters of floor area above ground. There are 8 retail floors; 39 office floors; 16 hotel floors, including double height lobby; 19 serviced apartment floors, including double height lobby; 39 residential floors, including double height lobby; 1 restaurant floor; 3 observation deck floors, including and observation deck transfer floor; and 8 mechanical floors.
Project Overview
The architectural expression of Seoul Light DMC Tower reinforces the sustainability strategies at the core of this design. The tower is shaped through gently curving forms and smooth transitions between the main northsouth and east-west facades. Perimeter mega-columns reinforce the expression of the transforming mass and provide a natural break to a series of solar louvers.
On the east and western facades, a pattern of both horizontal and vertical fins shield from early and late day sun, while horizontal shades on the southern face shield from high afternoon sun, thereby reducing internal cooling loads. Solar photo-voltaic panels are integrated into the shading system on the surface of specific zones of the louvers that receive the most sun, generating additional renewable energy. The tower’s soaring crown collects and channels light and helps power the building through wind turbines.
A large central void and two perimeter voids are carved through the upper half of the tower, creating an opportunity to bring in natural light, clean air, and capture renewable energy. The tower produces renewable energy by capitalizing on the principles of a solar updraft tower within the tall vertical central void. The design plans for six vertical axis wind turbines at the crown of the tower to be driven by the air as it is drawn out of the void; as the buoyant air rises, the air flow draws in cool, fresh air from below which also drives wind turbines at the base of the building.
The inner panels of glass that line the central void are designed with materials that catch, reflect, and hold light, which reduces the user’s reliance on artificial lights. An active phyto-remediation green wall is planted within the void to clean and replenish the interior air supply. Radiant cooling through chilled beams, radiant floor heating, and drawing tempered air through green atriums adds further efficiency. A gray-water reclamation tank within the tower drastically reduces the dependence on the public water supply and eliminates any need for irrigation water.
By taking advantage of naturally occurring events such as stack effect and solar radiation gain, Seoul Light DMC Tower is able to generate its own power and therefore reduce municipal energy consumption to a fraction of traditional levels. At the core of SOM’s scheme is an integrated sustainability strategy that uses the natural physics of tall buildings in order to generate power. Through the use of the stack effect and wind turbines located at the top of the building, SOM is generating almost 3% of the building’s energy consumption.
At the base, an eight story retail podium connects the tower to the surrounding urban fabric and encourages pedestrian flows through the site between the Digital Media City business district to the north and the recently rehabilitated Nanji public park to the south.
Archit ectural and Structural Features
Seoul Light DMC Tower is unique in that there are substantial vertical building voids cut through the top half of the tower. A central core runs through the retail podium and office floors for a more conventional and efficient structure through the bottom half of the building. Above, the core is divided by a large central void into two main bars that run north to south and is connected at the north and south ends with multi-story diagonal bracing to tie the core together structurally.
The void is approximately 308 m tall, spanning the residential, hotel, serviced apartments and observation deck. In plan, the void varies in profile between different programs, but is roughly 18m wide by 32m long. Elevators serving the hotel, residential and serviced apartments are located adjacent to the void so there is a direct experience of this architectural feature from the elevators. Stair and service elements are located on the unit side of the plan, separated by a public corridor that interacts with the void and allows access to passenger elevators.
Structurally, a series of mega-columns are arranged in the center of each face of the tower that rise nearly vertically that with the core form the primary structural system of the tower. As the tower geometry transforms in the corners of the towers, those columns are part of the secondary gravity system.
MEP and HVAC System
The project is designed to be a leader in sustainability and low-energy use. Four principles guide the sustainability strategy of the project: Reduction, Reclamation, Absorption and Generation. First, building energy use is reduced by optimizing MEP and HVAC systems, selecting equipment and lighting that is less energy intensive. Reclamation seeks to re-capture waster energy streams to reuse waste heat and reduce the amount of “new energy” used.
Absorption makes use of existing energy streams like wind and solar power available onsite. Generation explores methods to produce energy onsite through micro-turbines or fuel cells and improve transmission system efficiency. The building is designed with radiant floors in the residential and hotel units, chilled beam system in the office floors, and grey water collection and treatment for use in landscape irrigation. Trash is sorted for recycling to divert most building waste from landfills.
Cladding Peculiarities
As the tower is still in the early stages of design, curtain wall and enclosure development is still ongoing. In principle, the curtain wall is envisioned as a high-performance enclosure system that maximizes vision area glass and energy performance through high-performance coatings. All curtain wall panels will be flat and panel types will be minimized to balance constructability, efficiency and geometry articulation. Exterior shading fins are planned for the south, east and west facades to limit the amount of solar heat gain on the interior of the building.
Engineering and Construction Technologies
The central void, or solar engine concept of the building, is a unique proposal to use building stack effect to drive turbines. To understand the dynamics of air flow and performance of the wind turbines, CFD analysis of air movement within the building and within the void is conducted to simulate building conditions during different times of day and between seasons. Wind tunnel testing will be employed to optimize building shape and wind performance of the super tall tower.
Vertical Transportation
Due to the tower’s height and mixeduse program, vertical transportation is divided into programmatic zones. Local retail escalators and elevators serve the retail podium outside of the footprint of the tower. Lobbies for each program are located on the first two levels of the tower to give separate and distinct identities to the different functions. 18 local passenger elevators serve the office floors directly from the ground floor.
The hotel, serviced apartments and condominium programs are served by 3 express elevators each that connect ground floor lobbies to sky lobbies below each program stack. Transfer to local elevator banks occur at sky lobbies, which allow for efficient stacking of local elevators thereby reducing the number of elevator shafts needed.
Three express elevators connect the ground floor lobby of the observation deck to a double floor restaurant and observation sky lobby floor on the 79th floor. From there, passengers transfer to another set of high speed elevators that take them to the observation deck at the top of the building. This reduces the elevator run to less than 500 meters, which allows for the use of more conventional elevator technology.
Pedestrian and Vehicular Traffic
The entire project – tower and retail podium – is located on a single 37,000- square meter city block. A large pedestrian corridor runs in the north south direction through the site, connecting Digital Media City, a technology-oriented business park to the north with Nanji Park, a sustainability park and education center to the south.
This pedestrian corridor forms an important urban link that unifies the entire Digital Media City district and gives access to the Han River to the south. Vehicular access occurs at the perimeter of the site with drop-off zones and access to parking and loading below grade. There is a large transit hub and access to subway connections north of the site and public bus transportation access directly to the site.
Sustainable Components
The project is planned to maximize sustainable strategies to reduce energy and environmental impact, and also increase occupant comfort and health. The building’s four tiered approach to energy – Reduction, Absorption, Reclamation and Generation – is anticipated to reduce overall building energy use by 66%. These reductions come from improved building MEP and HVAC systems as well as the integration of renewable energy sources.
The building is designed with horizontal shading fins on the southern façade and a combination of both horizontal and vertical shading fins on the eastern and western facades. This reduces heat gain in the building, which reduces the anticipated cooling demands on the HVAC system. Potential locations for building integrated PV panels would generate up to 7,000 megawatt-hours (MWh) of energy. This energy could either be used in the building and surrounding site or sold back to the grid depending on demand.
The number of building integrated photo-voltaic panels to be installed is still being finalized, but covering 20% of the building would generate approximately 1,400 MWh of energy. This will keep the PV panels located in the lower portion of the building for easier access and maintenance. It is anticipated that the solar engine will produce up to 3%-5% of the building’s energy use, another source of clean energy.
A methane harnessing facility is located adjacent to the site, and wind turbines have recently been installed in a park immediately to the south of the site. It is anticipated that up to 20% of the entire building’s energy can be supplied from these near site renewable energy sources. On the interior of the building, green walls are planned at the perimeter atriums in the residential, serviced apartment, and hotel programs. They are separated into three sections ranging from about 16 to 39 floors tall.
There is approximately 3,000 square meters of wall surface in each program upon which green walls are mounted. These walls function to remove toxins and VOCs in the environment, refresh the air, and improve the well being and quality of the indoor environment. It is anticipated that these walls will reduce the amount of outside air needed, which will reduce the energy requirements to heat or cool additional outdoor air. With a lapse of less than four years we’ll see how much this new Seoul’s skyscraper is in line with its design concept.
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Information provided by SOM