A BOX INSIDE A BOX
This Project, in Bilbao Spain, integrated the façade of a listed, historical building with a new interior structure and distribution of the existing building. The original Rationalist façade had to be conserved as a representative element of the built heritage of the city of Bilbao, required by the Bilbao city planning department.
The existing interior structure of the building, however, was incompatible with the objectives of the client, as it was considered having weak patrimonial value, dysfunctional spatial distribution, heights which were not considered useful and dominating structural elements.
The objectives emphasized the need for a flexible, versatile and modular architecture able to adopt different distributions in the present but also providing the possibility for future change without generating restrictions due to partition walls and the building system ducts and components.
The final results of this particular situation consisted in leaving the original façade intact with a new building constructed inside. In other words, inserting a “new box” inside the “historical” box.
A HANGING STRUCTURE FOR LARGER SPACES
This new concept and redistribution of the interior had, as a primary goal, to increase the useful space of the different floors in order to achieve continuity, transparency and versatility desired by the client.The supporting structure was conceived as a hanging system at roof level, with two big steel cross beams which can support greater loads. This solution reduced the space occupied by the vertical structural elements, such as columns and walls, making more floor space available for interior rooms.
AN INTERIOR BIOCLIMATIC ATRIUM WHICH BRINGS NATURAL LIGHT AND SERVES AS THE HIGHLIGHTED FOCAL POINT OF THE BUILDING
The new space layout was based on the idea of introducing natural light inside the building through a vertical irregular glazed prism, essentially an empty volume, whose shape represents, metaphorically, the vortex of a tornado that has been introduced inside the internal structure of the building and alludes to the force of nature which represents a form of energy.
A LOW ENVIRONMENTAL IMPACT BUILDING WITH REDUCED CARBON FOOTPRINT
Conserving the façades actually presented itself as an opportunity to generate a bioclimatic chamber and was far from being considered a restrictive condition for the design. The space between the original façade and the new one and the interior courtyard has created bioclimatic spaces, which are able to interact with the indoor spaces by exchanging air using mechanical systems.
The control of the daylighting and the natural ventilation both allow for heat capture and heat dissipation (cooling). The optimization of the controls/contribution of the natural daylight also improves the end user´s thermal comfort conditions, and well-being in general.
The different strategies adopted with passive systems (external solar protection devices and the envelope’s thermal insulation) allow for a reduction of the energy demand as well as permitting the use of renewable energies (in particular, a geothermal heat pump system) to satisfy part of this demand.
As a result of these efforts, the conventional mechanical facilities, which usually use large duct installations, were substantially reduced, both in the space requirements (internal networks) and in the size of the systems components (mechanical/boiler room on the roof). The systems used were selected by their optimum efficiency criteria.
A reversible geothermal heat pump system covers part of the heat demand for the heating and cooling. In addition, a gas boiler generation system was also installed for heating and domestic hot water production.
The installation of an intelligent lighting system and a series of other energy saving measures has contributed to achieving the highest energy efficiency rating (Class A - Spanish regulation) possible. The total primary energy demand is estimated at about 137 kWh/m2 per year, according to the spanish regulation RD 47/2007 calculation method.
The use of the eco-design methodology, reduced energy, water and materials consumptions, as well as reduced waste generation, has also helped to achieve a high green qualification according to the American LEED standards by the U.S Green Building Council. The project received the highest possible rating - the “Platinum level ” of the LEED scheme.