Curved Geometry
Helsinki Central Library Oodi, Finland
The project represents a new era of libraries. The newly completed building in the heart of Helsinki consists almost entirely of public space and offers a wide selection of services. It is the new central point for the city’s impressive public library network. The design divides the functions of the library into three distinct levels: an active ground floor, a peaceful upper floor, and an enclosed in- between volume containing the more specific functions. This concept has been developed into an arching form that invites people to utilize the spaces and services underneath, inside and on top of it. The resulting building is an inspiring and highly functional addition to the urban life of Helsinki and the Töölönlahti area.
The Kansalaistori square (“Citizens’ Square”) across the street from the Parliament House seamlessly continues inside the ground floor level of the library building. The flexible spaces are suitable for both small events and large happenings. The movie theatre and the multipurpose hall can be used as a part of the open lobby space or separated off to cater for specific events. Walking through the ground floor offers a quick glimpse at the services available in the building. The sculptural wooden surface arches over the ground floor areas as a dramatic bridge- like structure. This innovative structural solution has enabled the creation of a columnfree public space to maximize the accessibility and visibility of the program.
The ‘ Book Heaven’ on the top floor, is a vast open landscape topped with an undulating cloud- like white ceiling. Here, the best features of the modernist library meet the possibilities provided by up- to- date technologies. A calm, serene atmosphere invites visitors to read, learn, think and to relax. From this level, visitors can enjoy an unobstructed 360- degree panorama view of the city centre. The middle floor, the ‘ attic’, consists of flexible irregularly- shaped rooms, nooks and corners inhabiting the spaces between the trusses of the bridge structure. The enclosed spaces are designed to accommodate both noisy and quiet activities. The stepped seating in the open central area of this floor is the result of the form of the cantilevering, twisting west façade.
By opening directly to the surrounding cityscape and by dissolving the border between indoor and outdoor areas, the building engages directly with the Töölönlahti area. The large foyer and the glass- walled multi- purpose hall on the ground level act as indoor extensions of the outdoor spaces. The arching wooden volume creates an entrance canopy over the Kansalaistori square forming a covered outdoor space that expands the building’s functions such as the ground level restaurant to the square. The
large public terrace on top of the canopy doubles the amount of public outdoor space available for library visitors and creates a new destination where people can meet and observe the city below. There will be three public entrances in the building: one in the south for the main pedestrian flow from the direction of the Central Railway Station; second, next to the Kansalaistori square to the west of the building shielded by the overhanging canopy; and the third for the visitors to the family library and the movie theatre in the north- eastern corner.
The spaces for maintenance and library logistics are located at the basement level. The administration and storage spaces are kept to the minimum on the publicly accessed levels to maximize the open and accessible nature of the library. The administrative and storage functions of the library will remain at the main library in nearby Pasila. The new library will be at the forefront of the renewal of the city’s library services. In addition to the core operations, there will be a wide range of services available inside the building alongside an abundance of lounge spaces and auxiliary services that support the operations such as Helsinki Info, the City of Helsinki’s information Center;
Europa Experience, the Center for EU related information; and Kino Regina, the National Audiovisual Institute’s movie theatre.
The spatial concept, based on three individual public floors is executed by building the library as an inhabited, asymmetrical bridge spanning over 100m over the open ground floor space. The bridge structure consisting of steel trusses and beams is supported by two massive steel arches, tensioned together with a reinforced concrete tension slab. The innovative structural solution has enabled both the construction of the flexible column- free interior spaces and the possibility for the construction of a future road tunnel under the site.
Secondary steel trusses support the cantilevering balcony and roof canopy asymmetrically from the arch structure, forming a unique structural design to accommodate both permanent and temporary functions for both the library and the public realm. The library has been built using local materials and with local climate conditions in mind. The wooden façade is made from pre- fabricated elements. 33mm-thick Finnish high- quality spruce has been used for the cladding. A specific grading and quality control system was developed for the timber, the sawing and the treatment of the slats.
The complex curved geometry was designed and manufactured using algorithm- aided parametric 3D design methods in order to achieve the required precision. The appearance of the façade will develop over the years towards
a deeper, richer version of its initial hue. The design of the building envelope is intrinsic to the passive energy approach adopted by the project team. Detailed analysis of the façade performance has informed the environmental solutions and has allowed the team to minimize the requirement for mechanical environmental control systems, which facilitates the highly flexible architectural solution. The glass facades allow for large amounts of functional daylight in the public areas, reducing the use of artificial light and enhancing the quality of the interior spaces as a multifunctional citizen’s forum.
The carefully planned placement and optimization of building services has enabled the flexibility of the spatial arrangements. All public levels of the building are equipped with access floors to allow for changes in use during the estimated 150- year life span of the building. The library building is extremely energy- efficient. Its energy consumption level is that of a nearly Zero Energy Building ( nZEB). This is mostly due to the efficiency of the building services. The material efficiency of the building has benefited among other things from the use of wood in the exterior cladding. Building information modelling was used in both architectural and engineering design, as well as in checking the compatibility of the designs. Building information model will also be utilized for maintenance.