DAEGU GOSAN PUBLIC LIBRARY
Albert Albareda Valls, Carles Pastor Foz, Sergi Muñoz, Bernat Riera / Youngho Yeo, Hosung Won, Heekeun Kim, Jiyeon Choi (KNWA)
Daegu - SOUTH KOREA
The Daegu Gosan Library is a new cultural center for the city that is large enough to provide the area with new character and a pleasant atmosphere in its surroundings. From a social perspective, designing the building as a cultural center in the area will create a new urban scope that will revitalize and maximize the space, offering new interior and exterior opportunities for leisure activities.
Due to the current situation regarding energy scarceness and environmental degradation, it is essential to plan new buildings as self-sufficient machines. We must be aware that eco-efficient centers are useless if the building is not provided with the required tools to minimize the effect of external environmental agents. Our goal is to design a polyvalent center that will be able to adapt to future changes that the library may demand. Thus, the building will be integrated into the site and will last through time, and may eventually become part of the city’s historical heritage.
In the surroundings of the building site, the city presents different urban typologies. The site, therefore, is in a disordered but strategically situated public space. The proximity of various schools, commercial facilities and public transport stations guarantee pedestrian traffic around the building.The building site is bounded to the north by a main road, and it is connected to the rest of the city through a large green area that shields the site from traffic noise while also providing an unshielded view of the city. On the east side, there are different kinds of buildings (commercial, residential and religious) that create a somewhat disordered urban fabric. On the west and south sides, the urban fabric is made up of detached houses that create a picture of consolidated blocks on continuous façades and straight streets. A little further on, we can find much bigger residential buildings that are part of our construction site landscape due their height.
The park that separates the library from the vehicular traffic will be the responsible for protecting the users and pedestrians that walk near the new building. The area is divided in two lineal stripes. The first one, next to Dalgubeol-daero, with vegetation that helps decreasing the noise and visually isolates the internal zones of the park. The second one, parallel to the first, with a hardest pavement that allows pedestrian circulation and its approach to the building from every part of the city.
Vegetation: Deciduous trees will be planted outside and in both courtyards, creating confortable spaces in summer and Winter, creating a new atmosphere. Low vegetation will also be placed, decreasing the visual impact of vehicular traffic.
Lighting: Street lights (powered by photovoltaic cells) follow building’s rhythm and alignments of the streets, producing an homogeneous lighting everywhere. On the other hand, lighting below public benches highlights the main access.
Water: Natural water ponds lead the way towards library’s main access and integrate the park into the urban fabric. This ponds are water accumulators that are used to water the existing vegetation (by a timed automatic circuit) and to provide water to the evaporative cooling system used in hot weather periods.
The building is settled in the area following the logical structure of the urban grid, matching its main axis close to the north-south one. This structure allows us to solve some important issues related to sustainability using geometry.
One of the most important elements of our proposal are the two patios with east-west orientation, which give urban style to the shape following the ‘non-consolidated’ structure on the east side to the ‘consolidated’ one on the opposite façade. In terms of organization, those two courtyards divide the building into three different sections, fitting the program properly and adding visual quality to the interior spaces with views to a controlled and quiet semi open-air atmosphere. However, the courtyards also have an important ecological purpose.
Analyzing the most adverse climate conditions, the courtyards have two positions that change the behavior of the building depending on the season. In the winter, they work as closed spaces that preserve the natural heat that comes from direct sunlight through the glass ceiling. The building, then, becomes a whole square dense volume that reduces the surface of exterior facades and takes advantage of those two huge ‘warming storages‘ while maintaining the semi open-air courtyard atmosphere and giving the possibility to use exterior spaces as part of a urban conception in cold seasons.
On the other hand, during the summer month, the patio is opened at its east-west sides, so that a cross ventilation travels from one façade to the other. Therefore, the entire building, when opened, is cooled. In the ‘summer mode’ position, the whole building has protection from direct sunlight thanks to the coverage of the patios. With this strategy, the whole building is shielded from direct sunlight to guarantee a proper energy balance.
Our proposal is comprised of a wide range of possibilities, but in our aim to reduce the CO2 emission impact of architecture, we strongly believe that the proposal becomes much more interesting when it respects the existing conditions, understands and solves current environmental issues and allows the next generation to better adapt to future conditions. Accordingly, the building could be adapted according to future needs to guarantee its long lifecycle, which has a tremendous effect in the ecological footprint of the proposal.
Another meaning of the concept flexibility in the field of architecture has to do with adaptability. Some particular parts of the plan will adapt to other uses or to improvised situations such as the multipurpose and lifelong study room surrounded by the two patios. This study room could be used for special events that could even differ from those specifically related to library activities.
The project arose originally with the concept of a ventilated surface hold by a grid of white metal pillars, leaving the space below to fill with the spaces for the library pretending to be the fifth façade of the building and working as the first and the principal filter. These elements are set up by a mesh of squared modules with steel beams every 4.7m in both directions and filled with two different components, depending on the space of the building that they cover. On one side, there are fixed blinds with photovoltaic panels integrated above the sections with the optimum angle to capture the maximum amount of sun radiation. These panels will generate approximately 120kw per year, on a surface of 570 sqm. The panels will provide electricity for the geothermal heat pumps and the lighting system of the building. On the other hand, the courtyards are covered with adjustable white metal slats of 1.20×4.35m letting the sunlight pass through them in winter and protecting the building from the aggressive sun radiation in summer. At the same time, the roof fixes other issues such as urban alignment with the surrounding master plan grid of streets and configures the general perception of the proposal.
The structure sets the order of the building establishing a regular module of 4.70×9.40m with the longest distance in a north-south direction, broken only in the front façade where it is modified to fix other important alignments and to highlight the façade within the public space. The guidelines of the general structural design consist of white rounded double-metal-jacket and concrete filled pillars, with an exterior diameter of 25cm and a square grid of beams in which we can distinguish those connected to the pillars that reduce the section size from approximately 60cm in the center, where it is lightened with holes, to 30cm at the ends where the node is articulated through a welded plate on the web of it to the vertical elements. The main beams reflect the moment diagram with a clear purpose to optimize it. And those in the east-west axis that maintain a normal IPN section, are embedded to the reinforced concrete walls in both sides of the building, that counteract the horizontal efforts in this direction and reduce the distances for placing the corrugated-sheet and concrete-filled slab on them. Finally the covering structure is a mesh of metal sections of around 30cm high, brought to its maximum expression reduced, connected to the interior metal jacket that overcomes the exterior one of the pillars with a bidirectional node.
The HVAC system in the whole building is resolved with central air machines thrown from the ceiling, so it’s a more effective solutions for a public space like libraries to be heated/cooled faster. Adopting this solution we let the floor free to raise it for technical reasons. The central machines consist of water-to-air heat/cooling pumps with geothermal source working with electricity generated by the photovoltaic panels in the roof. To reach a 100% self-sufficient energy building we estimate a maximum energetic charge in summer, considering the refreshing effect of the natural ventilation from the hidden patio, and in winter for heating, considering the ‘heating storage’ effect of the patios, an average demand of 60 KWh/sqm per year, so the need to heat/cool the total area of the building (3100 sqm) will be of around 186KW. If we have a yearly average yield of 0,31 KW/sqm (considering all the angles and bad factors that affect their position) from photovoltaic panels and with a total area of 570 sqm, we could produce 176 KW that could cover almost the total amount of the demand.
Rain Storage Tanks. Finally, we install water tanks to collect all the water from the rain, so we could use it to cover the bowel system needs of the building and to water the green areas of the proposal.
Choosing local-manufactured materials is another condition that we set as a key point in the proposal. Knowing about the intensive activity of the metal industry in Daegu raises the need to resolve the building conception in this material as far as possible to increase the local economy values and to reduce the ecological footprint. So the structure, the facades coatings, the blinding systems, frames for curtain walls… have been proposed from the original conception of the building bearing this in mind. Other materials will to be any manufacturers within a 600 km radius from Daegu.
More specifically we manage to use a triple-layered low emissive glazing in the
curtain walls with U values between 0,9 and 1,2 (being more strict with the north facade) which reduces 40% the energy loses compared to the average double-layered one. In relation to metallic materials our goal consists in using as much as possible recycled steel for structural elements and for coated panels in the facades. About concrete used for executing the retaining walls, the stiffener cores and the slabs, we manage using a special dosage consisting in reducing around 45% the amount of cement (which means the 5% of the CO2 emissions, meaning one of the largest greenhouse effect gases source) being substituted by granulated blast furnace slag (EGAH) which is a waste product of the smelting steel process, saving almost a tone of CO2 for each tone less of cement. It increases the natural resistance of the reinforced structural concrete as well.