Haikou Towers are projected to become the heart of the new Central Business District of Haikou, the capital city of Hainan, a tropical island in the in the South China Sea. The Masterplan comprises an ensemble of 10 Towers ranging from 150 to 450 meters height with an overall building area of 1.5 million square meters.
Two facing series of towers line up along the central axis of the new Central Business District and culminates in two landmark towers framing the central plaza of the district. On ground level the office towers are connected by a continuous undulating podium that accommodates the adjunct commercial facilities. The public realm between podium and boulevard expands with lush green spaces and water basins.
Form and structure of the 450m high tower have been directly informed by the program requirements of the building and the drive for an efficient structural scheme. The occupant needs for an office space and hotel room are distinctly different and have led to a shift in the structural system at the boundary between the two functions.
The shift in systems occurs at the hotel lobby area in the form of a large outrigger truss. This truss is purposefully exposed and integrated into the architecture to provide a clear distinction between functions and structural systems and is a key feature of the overall design.
The requirements for the office levels called for long span floors with column free interiors. This led to a megacolumn and megabrace solution in conjunction with a large core. In order to maximize the flexibility of the internal spaces, these megacolumns are pushed to the eight exterior points of the building, inclining and rotating with the form. Core and megacolumns carry the majority of the vertical loads. The large megabraces carry the horizontal loads due to wind and earthquake loading.
For the hotel floors there is a greater requirement for unobstructed views. To avoid any cross bracing on the perimeter of the building a structural system relying only on the core and perimeter columns is adopted. The perimeter columns are tied back to the core via a rigid connection at each floor plate and a large capping truss at roof level. The internal space of the core itself is designed as a full height atrium. To increase the openness of this space, the concrete walls employed for the office levels core are replaced with a steel diagrid.
The lower two thirds of the towers are reserved for office use with a total floor area of 185.000 square meters. The hotel lobbies are located on the 72nd floor with three floors of hotel service programs underneath. From the 77th to the 100th floors the hotel offers more than 46.000 square meters of floor space for guests. The sky lobby and the observatory floor are located on top of the tower.
The building height of 450m called for an intelligent, highly performative building envelope. The main requirement of the facade system is to react to differing sunlight conditions depending on the building’s orientation.
The proposed facade achieves this with a panel unit system which is divided into two parts – an upper opaque part that blocks sunlight and a lower transparent part. The opaque spandrel panels provide both external shading to reduce cooling loads and energy production by a photovoltaic coating on the south facade. The transparent glass facade in the lower part maximizes the use of daylight. The division in each facade units allows to fold in and out.
The folding angles vary according to the different sun-shading requirements, from north to south, from bottom to top. The increase of the folding angles allows for a smooth transition from the flat units on the north side to units on the south facade with a maximum angle of 30 degrees. The continuous differentiation of the facade harmoniously blends with the large-scale structure of the tower.
Architect: HENN Location: Haikou, China Design Team: HENN StudioB: Leander Adrian, Daniel da Rocha, Martin Henn, Kaowen Ho, Markus Jacobi, Agata Kycia, Paul Langley, Klaus Ransmayr, Max Schwitalla, Wei Sun, Xin Wang, Mu Xingyu Local Partner: IPPR International Engineering Corporation Consultants: Arup, Front, Lumen 3 Program: Office, Hotel, Conference, Commercial Status: Competition 1st Prize Area: 320,000 sqm Images: Courtesy of HENN