The competition for new Ljubljana administration centre of 60.000m2. Ofis Arhitekti's brief proposed several departments to move to the same site but occupy different buildings. The heart of the centre is the main hall where citizens could also arrange all the documents.
The site is just on the edge of the Ljubljana city centre, by the river and already occupied by some existing protected buildings.
As such, the area represents a chance for unique architectural rearrangement with its identity and to become a sort of symbol and landmark area of contemporary Ljubljana architecture. The mixture of public and restricted relations inside the program calls for complex organisation – both inside and outside.
Ofis Arhitekti's project took idea of cylindric organisation of existing protected garage-building that is in the middle of the site.
Site location plan
Three new buildings are designed as cylinders related with loops of spaces in different heights.
the middle of each cylinder public and entrance area is organised, offices are arranged around the circles. The logic of connected and disconnected departments follows mathematical model of intersections and unions. Two departments that share meeting spaces are connected in various floors with loops – bridges which create unique space.
Loops and circles create complex landscape with external plazas, squares and bays of greenery. Outside space is connected but still rich and complex of public and semi-private areas. It connects to the river promenade.
A sustainable design aproach is taken to achieve optimized environmental conditions with a minimized energy demands in three steps: reducing the energy and meeting remaining conditions with high-performance building-integrated systems, and sourcing those systems as much as possible with renewable sources.
One of the core ideas of the sustainable design concept is to heat and cool working areas like offices and use the exhaust air of these offices to condition the atrium, which is used as a big buffer space. The external facades will feature a high performance glazing and an adaptable external shading device to reduce solar gains in summer.
The concrete slab imbedded pipe system provides cooling without draft problems and in winter comfortable radiant heating. In summer the cooling of the offices spaces will be achieved for major amount of time just using the slab system. The decentralized ventilation units vent fresh air into the rooms and serve as peak time cooling in summer. During winter the fresh air will be heated inside the units and distributed into the rooms using the displacement ventilation principle. An overflow to the atrium allows the exhaust air to flow from the offices into the atrium and through louvers in the roof to the outside.
The atrium itself is a buffer space, which is naturally ventilated and heated/cooled by the exhaust air from the offices. This means the temperature in the atrium will swing from 15°°C in winter to ambient conditions at the upper levels in summer (temperature stratification). To minimize the peak summer conditions, features inside the atrium like the water wall and floor cooling system will condition this space in addition. The water wall is used for cooling and dehumidification purposes in summer, whereas in winter the water will evaporate and humidify the air. Special areas inside the atrium will get this “own” climate. Especially for a front desk this local climate is important to guarantee adequate working conditions.
The energy supply system is based on natural resources like river water heat exchanger to provide cooling in summer as well as heating - in combination with a heat pump - in winter. Photovoltaic cells integrated in the atrium roof generate power. Another objective of a sustainable building approach thrives to minimize of energy intensive materials instead local available, sustainable design materials will be used.
Location: Ljubljana, Slovenia
Type: Offices with public program
Client: City Municipality Ljubljana
Gross area above ground: New buildings: 42,288m2. Existing buildings: 16,868m2. Existing buildings + new buildings: 59,148m2
Gross area underground (new buildings): 20,800m2
Construction ratio: 17%
Architecture: Ofis Arhitekti
Rok Oman, Spela Videcnik
Project team: Andrej Gregoric,
Magdalena Lacka, Katja Aljaz