By filling a void with an element analogous to the one that is missing, the material intervention would be more integrated into the whole. As it would be a minor element of the building, of a type whose copies have been changed over time, the impact, both of its placement and its removal, would be minimal."
It seems that those responsible have not wanted to indicate specific dates and in statements by the cathedral administrator to local media, Mario González, has commented that «it will not go further, or at least there is no forecast on the execution of the project. It was a contest of ideas and so far it has come.
A "veil" to protect the portico of León Cathedral by Julio César Moreno.
A "veil" to protect the portico of León Cathedral by Julio César Moreno.
Project description by Julio César Moreno
INTEGRATION
As a protection, we propose the installation of a light transparent membrane suspended from the upper part of the portico, by means of a new load-bearing element that would be closely related to the set of crests of the building.
The cresting, although they are minor elements of the buildings, have interesting compositional and constructive functions. The main one is that they crown the buildings or their parts in a more delicate and gradual way than do the cornice or the eaves, serving at the same time as a parapet to prevent falls from height.
Throughout the more than 700 years of existence of the Gothic cathedral, different types of crests and parapets have been placed and removed, substituting one for the other according to the times. In the case of the portico, the original was preserved until the end of the 19th century, when it was removed. Since then no other has been placed in its place. With the lack of that old rosette sill, a somewhat abrupt cut can be seen between the portico and the façade.
We propose to partially recover this old element by installing a new crest to support the protection of the portico. It would have a new design, inspired by the pavilion of the Nordic countries in Venice, by Sverre Fehn. It would make number 16 of the historical sequence, according to the count that we have made from both those found in corridors and eaves, as well as the remains of others that are kept in the cloister. We provide a graphic record of the 10 best preserved, plus the one we propose to install.
The design summarizes the functioning of the Gothic structures in the verticality of the supports with the catenary arches of the channels. It even seems that each interval between plates reflects the space that the towers form when they separate from the central nave.
By filling a void with an element analogous to the one that is missing, the material intervention would be more integrated into the whole. As it would be a minor element of the building, of a type whose specimens have been changed over time, the impact of both its placement and its removal would be minimal.
CONSTRUCTION AND STRUCTURE
This new element, which would work as a cantilever from a support base placed at the rear of the terraced roof, would fulfil the function of supporting the EFTE veil without overloading the lightest part of the façade front. This would be achieved because this cantilevered configuration carries the weight to the resistant mass of stone located at the back, next to the gable walls between doorways. It would be built in several prefabricated concrete bodies, whose aggregate would be crushed gravel from Boñar stone. Between the cantilevered pieces it is planned to place some channels for protection from the rain, made with reinforced resin that would contain Boñar stone dust in its mass. The entire set of elements to be installed could be removed without risk to the monument and with the sole trace of the anchor holes, which would remain hidden.
EFTE has been chosen for the protection membrane because it allows it to be suspended from the upper part, lightening its profiles and avoiding resting on the ground, under which the archaeological remains of the ancient hypocaust of the Roman baths are found. Compared to other transparent or translucent materials such as glass, EFTE has the advantage of being light, insulating, resistant and flexible, and it repels dirt because it is self-cleaning. Its great transparency can be regulated with additives and with the printing of shading patterns, which are usually white or silver. We proposed adding some pigments to the mass of one of the layers (-15% opacity) and silk-screening another, with a quatrefoil pattern in memory of the ornamental rosette motif of the old sill.
It would be stabilized against wind pressures with a frame and with tension rods and profiles anchored to the buried base of the building, at a depth less than that of the archaeological remains. The union of these bases would be rigid and solidary to the factory of the buried walls. However, at the other end of the assembly, where the bases meet the porch roof, elastic supports are provided. With this objective, they would support the bases on neoprene bands, with the capacity to reduce vibrations due to the dynamic action of the wind.
ADVANCE OF THE NEW AIR CONDITIONING, BY ÚRCULO INGENIEROS
During the hours of solar radiation on the façade, there will be natural convection in the space between the EFTE sheet and the stone, which, being air heated by the greenhouse effect, will dry the façade by increasing its temperature (desirable circumstance in winter to avoid possible frost).
On the other hand, this heating will accumulate in the facade, giving it certain thermal inertia during the night, attenuating temperature variations.
As radiation data for the west orientation in León, approximate values have been extrapolated, which vary from 9,580 kJ/m² in January, to 16,280 kJ/m² in February.
Regarding surface condensation: Long-wave radiant exchange between the stone surface and the cold layers of the lower atmosphere is an important heat transfer process.
During night hours, or with the sun at low angles of inclination, (which occurs in the west orientation), the result of such transfer is a net loss of heat from the façade. This can lead to a drop in the surface temperature so that it becomes lower than the ambient temperature. If it reaches the dew point of ambient air, condensation will occur. In our case, this undesirable circumstance will be minimized by the thermal inertia of the stone, heated by the aforementioned greenhouse effect.
Another, undesirable, effect on the facades is that of windy rain, which is largely avoided by the protection sheet. (In León, the prevailing wind is from the West).
Incident solar radiation on the façade represents its greatest thermal load. It is short wave radiation that depends on the angle between the sun and the perpendicular to the façade, which in our case is an unfavourable factor. The planned EFTE sheet, with two layers of material, has a solar gain of 0.29, which is a good value for reducing incident radiation.
