Sumit Singhal loves modern architecture. He comes from a family of builders who have built more than 20 projects in the last ten years near Delhi in India. He has recently started writing about the architectural projects that catch his imagination.
City Municipality Ljubljana in Ljubljana, Slovenia by OFIS architects
April 23rd, 2011 by Sumit Singhal
Competition 2009, third prize
Competition entry for a new Ljubljana administration centre of 60.000m2. The 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 Ljubljana city centre, by the river and is already occupied by some existing protected buildings.
Brutto surface above ground:
As such, the area represents a chance for unique rearrangement with its identity to become a sort of symbol or landmark of contemporary Ljubljana architecture. The mix of public and private areas inside the program calls for complex organisation – both inside and outside. The project took the idea of cylindrical organisation from the existing protected garage-building that is in the middle of the site.
Three new buildings are designed as cylinders related with loops of spaces in different heights. In the middle of each cylinder the public and entrance areas are organised and offices are arranged around this. The logic of connected and disconnected departments follows the mathematical model of intersections and unions. Two departments that share meeting spaces are connected in various floors with loop-bridges which creates a unique space.
The loops and circles create a complex landscape with external plazas, squares and bays of greenery, which connect to the river promenade. Special care was also given to achieve optimal environmental conditions with minimal 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 key ideas of the sustainability 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 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 majority of cooling for the office spaces will be achieved 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.
As the atrium is a buffer space, which is naturally ventilated and heated/cooled by the exhaust air from the offices it 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 a water wall and a floor cooling system will condition this space in addition.
The water wall is used for both 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. This local climate is important to guarantee adequate working conditions. The energy supply system is based on natural resources like a 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 will help to generate power. Another objective of a sustainable building approach is to minimize the use of energy intensive materials. Instead, locally sourced, sustainable materials will be used.
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