Prague 7, Letna, international competition for National Library building design, 2nd stage
Pedestrian access and the main public entrance are situated off Milady Horákové street. At the north east corner of the site the mass of the upper floors (L1) form a canopy over a great carrefour that brings the Letenská pláň plain into the library and creates a grand public parvis out of the entry level of the library. A landscaped public area, for gathering and casual encounters is created around the main library entrance. This area steps down to allow natural light into level – 1 while respecting the setback requirements created by underground City Ring Road. Entry into the main library level is via bridges that pass above the landscaped public area.
Ground floor – The main library entry level is a grand high space, bending and sloping to connect on all sides to the various topographic conditions set up by the Letenská plain. Generous light wells bring natural light into the focus point of the entry floor. This grand high space culminates as a public space at the south side of the site extending the greenery of the Letná Park into the building. The surrounding greenery of Letná becomes visually a part of the main level of National Library. From this public space is the VIP entrance to the building. The VIP entry is connected via independent lifts to the restaurants and exhibition areas on the top floors. The library has 4 above ground stories on the west boundary and steps up 1-2 floors towards south/east corner. The vehicular access is within the set back of 23m from the library building’s underground floors, as well as the detour of public transportation buses from Milady Horákové Street.
From the open plan of the ground floor of the main library hall rise four different volumes. These are clustered around the giant light well. Where required by function these volumes are interconnected via bridges. The largest volume, the National Archival Collection is opaque, the other volumes have different degrees of transparency and colouration.
Within the main atrium a large circular ramp connects the libraries entry level with the upper floors. This main library level is naturally top lit during the day. The play of the light and colours among the general massing of the interior public space animates general orientation and identification within the building.
The vertical masses are pinned down to the ground with strategically distributed vertical cores containing vertical movement – elevator shafts, stairs, M&E services. These vertical cores are also connected to underground floors.
Over the envelope of the four basic masses is “stretched” in differing distances a double skin which combines a variety of materials and technologies including- solar units, photovoltaic units to the south, SW and SE and transparent or translucent surfaces toward the interior of public spaces.
The main public access from the north east corner is clearly identified by the buildings massing, surrounding landscape, access paths, and ramps. For the access of light into the underground level -1 the adjacent landscape is bent down creating a courtyard along the north and west boundary. Additional lightwells and courtyards exploit local topographic conditions and bring ambiance to lower levels.
The main basic functions are organized in 4 volumes above the main library hall ground floor:
- Acquisition Division (1.1) & National Bibliography Cataloguing Division (1.2) in one block
- Reading Rooms (1.3) all in one block
- Collection Management Presentation Division (1.4) in one block
- National Archival Collection Management Department (1.4.3) with Multipurpose halls and Exhibition area on top floor
The volume of the reading rooms starts on the ground floor with open stacks and a study area. The rest of the ground floor is an open area with access lobbies to the upper floors of all other departments. The information booth counter, the principle light well with the main spiral ramp to the public areas on the top floors, panoramic elevators going to the restaurants, terraces, exhibition halls, bridges flying across the spaces between the 4 masses are all key components creating the ambience of the “transparent” main library hall. The Literary café is situated towards the greenery of Letná park in the south.
Reading rooms are on several floors and are set in quiet zones located in the southwest corner. Reading rooms on higher floors have fabulous views of Prague Castle and Petřín Hill over the greenery of Letná and the King’s garden. Public areas on the top floors (L5, L6) – terraces with restaurants and galleries – multipurpose halls and exhibition areas also enjoy magnificent views of Prague veduta, set above the tree crowns. These areas are accessible via exposed panoramic lifts or public ramps. VIP access is separate via lifts located at the south side park area.
Parts of the above mentioned departments are placed on the lower levels – These are interconnected by vertical cores. The libraries remaining functions are situated in the underground floors.
On the -1 Level is the loading dock with the distribution of books and material to all library divisions. The library operation and management division is located on this level with offices lit by natural light via courtyards cut down on the western side. A similar system of light courts is used for the Main Library Hall background and the Library System Department. Also on this level is the Universal Collection Management with distribution to the same department on lower floors.
On -2 and -3 Levels the Universal Collection Management occupies both floors + parking (1.4.4).
The shapes of the 4 main volumes above the ground floor are formed by concrete slabs and a system of steel frames, bracing and columns to obtain desired forms. Concrete vertical cores pass through out of all floors including the lower levels down to the foundations. These cores also act as bracing for the spatial frame. The bridges connecting the various departments are also designed as steel bracing. The volumes over the main entry in the north and north east are cantilevered with steel beams. This design to be further coordinated with the design of the City Ring Road in order to insure structural integrity.
The double skin façade is connected to the steel frame. The inner layer has all the properties of an insulated wall to satisfy the prescribed library climacteric conditions. The outer layer is hooked onto a system of spacers which enable the facade to react to variable sun conditions. The heat energy between these two layers is recuperated for additional use or recycled within the system.
The future extension of the National Library after 2040 is placed underground. This extension is shown with a green roof extending the park of the Letenská pláň plain which will continue to terminate with the present design of National Library of Prague.