Traditionally, the City Hall had a noticeable institutional character and its presence was severe and somewhat hieratic. As time went by, it began to lodge other functions and become a place of meeting for the citizens. As a result, its image became smoother, and thus the architecture reacted becoming more pleasant. Now, in the beginning of the XXI century, the City Hall is transforming into a model of interaction with the environment by implementing mechanisms in the face of increasing energetic challenges that our society can no longer deny.
The location of the building displays a conflict between two landscapes: at one side, the urban fabric and a tough and desolated square; and to the other side, the natural environment, facing a park that grows towards the south. The square and the park turn their backs to each other, separated by an asphalt belt. The new City Hall serves as a mediating agent for both landscapes, dissolving their limits and therefore becoming a built hybrid that assimilates these opposing characters. This will produce a zone of osmosis between the building and the place, not mimesis nor radical rupture, but an infiltration that settles a common agreement.
The building is made up through a superposition of membranes. The inner layer, with a strict geometry, is formed by a double translucent skin separated by an air chamber. It guarantees the decrease of the energy and lighting consumption. The external membrane is a metallic latticework with an organic form where vegetation will grow producing a “cloud” that will change its density and colors throughout the year. The vegetal canvas is composed by the Virginia creeper (Veitchii), which climbs and covers the facade during the summer, protecting the building from the solar radiation and also serving as a refreshing device. During the fall, it acquires spectacular red shades and in the winter, due to its deciduous leafs, lets sunlight pass and heats the double inner skin.
The Virginia creeper does not take root in the soil but rather in a building that paradoxically sinks more than seventy meters deep in the ground to obtain enough geothermal energy to supply the heating and refrigeration needs. After a rigorous study of the energetic behavior with powerful digital analytical tools, the building received an outstanding A level qualification with a reduction of power consumption of 60%.
Thus the building will be perceived as a landscape that changes, displaying the course of days and seasons. In summary, it acts as an index of the everyday life and the yearly cycles of the Noain citizens. The new Noain City Hall is equipped with passive and active systems of energy saving. The development of both systems was included from the early stages of design, so that the final outcome of the building is clearly determined by their presence. The project has been subject to an energy rating, resulting in a 60% saving.
Lighting usually involves the higher energy consumption in an office building. To minimize its impact, the building has been built with the aim to obtain the highest level of sunlight in all its areas. It’s conceived as an addition of layers. The center of the building is an empty space, covered by a skylight that introduces northern light to all the circulation spaces. Along this void the main staircase connects the different levels. Around it, a corridor provides access to the offices and meeting rooms. These areas are separated by divisions that do not reach the ceiling, so that the central sunlight enters through the private spaces, as well. The facades are composed of a translucent double skin. Glass inwards and polycarbonate outwards, separated 25cm. The sunlight, therefore, enters through the whole building envelope.
The outer layer is an ‘organic’ grid of flat steel bars, located between 2 and 3 meters away from the double translucent skin. Horizontal bars serve as ‘brise-soleil’, reducing the impact of summer sun. Over this grid, creepers grow and, eventually, will cover completely the building. The creepers are deciduous, and they work as a seasonal filter, absorbing solar radiation in summer and allowing it to heat the air chamber between the double skin in winter. During the night, the vegetation reduces radiation losses and prevents from inner temperature drop. Furthermore, the ‘green growing grid’ provides added benefits moistening the environment, softening the temperatures and absorbing CO2.
The main source of energy is geothermal. The building exchanges energy with the ground through heat pumps and a set of probes 100m depth. Geothermal energy is a high performance system. It takes advantage of stability and low thermal oscillation of the ground to exchange heat with it through a network of vertical pipes where water flows. This exchange, allows interseasonal energy accumulation, giving heat to the ground in summer and extracting it in winter. The distribution of cold and heat inside the building is done through a radiant floor. It consists of a network of micro tubes embedded in the floor, turning all the surface in a large heating and cooling system. This system works with lows temperatures of transmission and avoids draughts, ensuring high standards of comfort.
A small gas boiler placed on the top of the building improves system performance in those periods when it is necessary to reach required temperatures instantaneously.Moreover, the building is equipped with mechanical ventilation, that satisfies the needs of air renewal and modifies its hygrothermic conditions. The top skylight works as a solar chimney, allowing the evacuation of hot air in summer through its motorized grilles. On the other hand, the double skin air chamber has manual grilles beside each window whose manipulation allows to accumulate or dissipate heat. Finally, all systems, lighting, heating, cooling and ventilation are controlled and regulated by a central computer. It allows fully optimize energy efficiency while meets the required comfort conditions.
It should be noted that, in the Noain City Hall, technology is not seen but is perceived through other senses. The organs where functions reside, become kilometres of pipes, whether geothermal extraction, microcapillaries distribution, telecommunications fiber optic, or lighting electricity. The user can not see the different systems, which go unnoticed by any visitor. Perhaps he can sense the lighting, temperature or movement sensors embedded in the suspended ceiling, which serve to rationalize energy consumption.
All systems are still there, but no longer are the main character of space. The organic metaphor as a body with visible organs with defined functions is replaced by another in which the body is only the skin, the boundary between exterior and a conditioned interior. The organs are not seen, or have been restructured into fuzzy systems of energy management and information. In short, the more advanced technology, the more invisible it is.
Location: Navarra, Spain Architects: ZON-E Arquitectos| Nacho Ruiz Allén y José Antonio Ruiz Esquiroz
Collaborators: Lucía Martinez Trejo y Sara López Arraiza
Quantity Surveyor: Miguel Larraburu Sorozábal
Structure: Ingeniería Lauquiegui+Boreas
Engineering: Ingeniería Lauquiegui, Gealia Nova
Energy Consulting: Miyabi
Gardening: Área de jardinería y Agenda 21. Noain City Council
Client: Noain City Council
Construction manager: Enrique Goñi Viamonte
Furniture: M40, Paymo
Photos: Pedro Pegenaute
Starting date: January 2007
Finishing date: May 2009