Council on Tall Buildings and Urban Habitat

Postitalo Torni
Gabriel Huerta

Third Prize Winner
Site: Helsinki, Finland
University of California Los Angeles
Competition: CTBUH 2nd Annual Student Competition - 2012 Reimagining Tall

Building overall
Detail Section
Parasitic Aggregation - Systemic Growth Logic Case Study
Varying Densities - Surface Articulation Studies
Site Plan

Building Section
Building Use Diagrams
Strangling Growth

Postitalo Torni
Strict zoning ordinances (limiting building height) and a strong sentiment towards historical preservation have contributed to the absence of the high-rise tower in the Helsinki skyline. The research was interested in the development of a parasitic type structural approach in cities that are resistant to towers.

The project is sited opportunistically at the cusp of the old city center and the developing cultural zone of Helsinki, making the tower an iconic beacon from the harbor waterfront. The selected host building for the proposed tower is the Postitalo (the former main post office building) as it is a building already in violation of zoning height ordinances thus justifying further vertical development.

Parasitic Aggregation
The Strangler Fig (e.g. banyan) was the biomimetic inspiration and the basis of the parasitic systemic logic of the research. The “strangling” growth habit of the strangler fig is an adaptation for growing in dark forests where the competition for light is intense.The original support tree of the parasitic plant can sometimes die, so that the strangler fig becomes a "columnar tree" with a hollow central core.

The research explored this idea of parasitic aggregation as a system that is implemented both at the micro and macroscale of a tower. At the microscale, the structural skin adapts the strangling logic to form varying densities of articulation from aperture to surface. More technically the research looked at developing deliberate control of the pattern articulation. At the macroscale, the building adapts the growth logic of anchoring onto a host building and growing vertically into a self supporting hollow column. This allows for being able to create a tower without demolition and allows for the continued inhabitation of the host building.

Structural System and Multiplicity of Performance

The structural system became the emphasis of the project as it provided the opportunity to rethink the convention of the tower as not having to be centrally loaded. By being a hollow column the tower allowed for more of a Centre Pompidou approach of loading all mechanical systems and circulation on to the building skin allowing for a multiplicity of performance of the structural system. Elevator cores, escalators, and  stairwells are embedded into the structural skin through a variability of thickness and depth allowing for more of an interaction and actual inhabitation of the skin. Mechanical systems such as HVAC and plumbing would also be integrated into the monolithic mass and would be locally distributed to the floor plates which sit on the skin much like bookshelves.

By being liberated from being a centrally loaded tower the newly proposed Postitalo Torni (Postal House Tower) has more of a freedom as to the layout of floors, such as allowing for large multi-floor voids. Because of the extreme climatic condition of Helsinki the double glazed skin delaminates to form these inhabitable voids that promote a stack effect and are a transitional space between the conditioned interiors.

Programmed as a primarily residential tower, with commercial program at the top and foot of the tower, the void played the role of forming neighborhoods within the tower through communal lobbies. Floors terrace onto these communal lobbies and are further activated though the discontinuity of elevator cores which form an interchange on these lobby levels.