The Agbar Tower, located in Barcelona, is a singular 34-floor office building with a height of 115 m. The façade is designed as a double skin enclosure to exhibit the following flexibility and performance: energetic and light control, natural ventilation, high acoustic mitigation, different orientation, and necessity suitability. Moreover, a homogeneous was achieved as the architect wanted to obtain the same appearance. The interior skin façade is conceived using two different construction systems: the shaft, built with a conventional ventilated façade and windows, and the dome, developed as a curtain wall (Figure 1). Additionally, the exterior skin is continuous in all the envelope surface, thus unifying the exterior image of the tower.

The shaft contains an edge concrete lead-bearing wall with small square holes, inspired by fractal rules, which indicates where to incorporate standard windows in lacquered aluminium carpentry and double glazing (Figure 2). The wall consists of a superposed ventilated façade comprising a rock wool panel insulation containing 80-mm ventilated chamber corrugated aluminium sheets, which are curved and thermos-coated in 45 different colours. The structural system is completely modified in the dome, shifting the concrete load-bearing wall to a steel profile structure generating a colossal dimension mesh. This structural modification enables the creation of a glazed dome, constructed with a standard modular curtain wall that can be easily adapted to the double curvature polygonal form. The glass in the modular curtain wall is a double-glazing screen painted blue with blue layers inserted.

In all the tower enclosures, the exterior skin façade is built in glass slat continuous skins to unify the two construction systems used in the interior skin. The slats are made of security laminated glass with different compositions by combining serigraph, printing, extra light lass, and conventional glass based on the required project and distributed following geographic orientation, interior views, or inclination in the dome. The 52.000 installed glass slats are supported by aluminium brackets, which are placed 90 cm away from the interior façade, thus generating an air cavity that improves the global performance of the façade and enables the integration of the catwalk for maintenance.

The glass slat system support for the double skin façade is considered the brainwave idea of the project, as the key element that enables obtaining the desired images and performances (Figure 3). A conventional system inherited from the traditional kitchen windows in Barcelona houses has technically been developed and thus can be used in one of the most emblematic buildings in Barcelona. This project realized an aluminium bracket that can be regulated in different positions.

The systems consist of 52.000 glass salts of 100 $\times$ 30 cm dimension laminated glass supported by two aluminium profiles in the short sides, glued with structural silicone, fixed to the vertical profiles with plates that enable different angle positions based on diverse requirements and disposed of in assorted combinations of inclination, colour, and serigraphy percentages. The solution offers a continuous layer that adapts to the tower shape.

The Porta Fira Hotel Tower located in Barcelona is set out with a floor that turns on itself, rotates as it rises, and is translated on its vertical axis from a specific height simultaneously. Finally, it opens like a vegetable shape. Because of the complex geometric composition of the building, the façade is designed with two different skins, enabling each skin to satisfy specific requirements. First, the interior façade consists of a modular curtain wall light system with aluminium profiles and double glazing in the vision areas and opaque panels conceived to guarantee acoustic, thermal, fire protection, and water tightness requirements. The modular curtain wall is disposed between the slabs, thus horizontal profiles are indispensable to realize a tight joint in the system. The vision area casement window is used both for ventilation and cleaning of the glass. An aluminium panel sandwich addresses the opaque areas, formed by a lacquered aluminium sheet, thermal insulation, and galvanised steel sheet in the interior (Figure 4). To improve the fire protection, acoustic, and thermal insulation performances, the sandwich panel rock wool or fibro silicate boards are installed in inside, following specific requirements in each floor.

Second, the exterior façade is outlined as an enclosure to award texture and shape to the tower. The skin comprises independent 1.00 red aluminium tubes fastened on the ends with swivel joints to enable the desired twisting from the floor to the crown of the building (Figure 5). This tubular skin functions as a solar protection element as it reduces 50$\mathrm{\%}$ of direct solar radiation in the inner skin. The assembly site is built without auxiliary tools in the exterior oblique to first assemble the exterior red aluminium tube skins from the inside followed by the interior vertical enclosure. Owing to the light weight of the modules, they can be positioned from the inside without additional machinery.

The brainwave that enables the development of the facade outer shell in the project is the round swivel that forms part of the fixation system of the tube lattice (Figure 6). A custom element in the car industry is adapted to be used in the façade construction system, enabling the free displacement and combination of different angles (that are not repeated in any situation all over double skin façades). At the end of the red aluminium tubes is disposed of a turned polyethylene bit to facilitate the joint between the tube and swivel joint, obtaining an articulation in both tubes ends to enable the adaptation to the main shape of the building.

La Querola from Ordino is a residential complex comprising a seven-building assembly, adjoined to the mountain. The building façade design can reproduce a natural element on an increased scale, aiming to address the definition of ‘querol’: a geological accident formed in a flat landscape where it emerges an enormous stone with stratified layers. A dry joint construction system was proposed to construct the cavity-ventilated wall façade of the project. Therefore, the cladding could adapt to the building shapes with the required tolerance and flexibility. The exterior cladding executed in natural stone is variable in different levels and sections generating unequal planes with irregular folds. Furthermore, the windows have irregular and variable shapes and large dimensions, leading to difficulty in realising a type detail. A steel tube grid filled with concrete blocks in the interior enclosure was selected (Figure 7), enabling substructural integration in the vertical plane of the tipping windows and supporting the exterior ribs ensemble, where the exterior stone cladding is fixed. The same system used in the façade is applied to the roof, as the enclosure is continuous.

The brainwave idea in this project is as simple as the slat cladding fixation system, (Figure 8) which was developed in the prototype execution phase. Initially, the idea was to be applied in hole fixations. However, as shown in the prototype, the system has limitations in the execution of the façade. A loading test was conducted to determine the viability of the concealed fixing embedded in a slate piece. Thus, previously discovered problems were prevented. A single fixing element used with another cladding type of materials was tested, and its performance with slate materials, which are usually fixed via hole fixations or supporting components, was verified.

The Isla Blanca building located on Ibiza Island is a commercial and luxury housing complex. Its façade consists of two distinguishable parts: a commercial façade, which aims to be as transparent as possible, and the housing area comprising all height windows, terraces with jardinières, and solar protection termed ‘voilettes’. All the façade components have to be adapted to the floor geometry: windows, partitions, ventilated façade, jardinières, and eaves. The opaque façade coinciding with the slab edge and the handrail are resolved with white and smooth texture ultra-high performance fibre reinforced concrete (UHPFRC) prefabricates panels. Between the joints of the panels, the cantilever elements enable the fixation of the solar protection eaves or ‘voilettes’ (Figure 9). The glazed façade is built with all high windows adapted to the curved geometry by polygonal lines.

The predominant project elements are the huge solar protection eaves. Therefore, if an almost 3-m length projection is generated, the aim is to search for a big dimension protection component with extremely lightweight. The brainwave idea that leads to the construction of these ‘voilettes’ is the chosen material. UHPFRC is a material that can be designed and produced with high resistances, lightweight, and slender complex forms as a result of the fibbers added to the concrete (Figure 10). The ‘voilettes’, including the high capacity of the UHPFRC, had a complex characteristic added-on. The components were perforated in more than 50$\%$ with only 5-cm thickness, leading to a mesh with 90 holes. Therefore, several tests should be conducted in the workshop. The resistance was guaranteed and did not break or deform significantly, similar to the development of the casts and the cast-fulfilled system. Finally, the ‘voilettes’ were built using two different modes: concave and convex.

The Mohammed VI Tower located in Rabat is currently under construction. It is designed with a height of 250 m and therefore will turn into the tallest building in the African continent. The façade diverges the north and south orientations, and the north skin searches for transparency with straight-up ribs termed ‘epines’ to accentuate the vertically. The south façade is perfectly opaque to introduce photovoltaic panels. Although they are conceptually different facades, they are resolved using the same construction system. All the façade enclosure is constructively solved with a modular curtain wall with different widths in the tower perimeter, following the project requirements and dimensions. The curtain of the north façade is modulated in 1,70 and 0,60 m modules, an alternating vision module, and an opaque module (Figure 11). The 0,60-m opaque module is used to situate the white aluminium ‘epines’ to remark the tower verticality and reflect light to the interior of the floors of the tower. The ‘epines’ are suspended in the opaque curtain wall module with a tubular substructure that, in addition, stiffens it. The materiality of the ‘epines’ was investigated in the prototype phase to verify if both the material and suspending system accomplish the constructive and aesthetic requirements. Conversely, in the south and intermediated façades the same system, i.e., an opaque modular curtain wall, is used. Overlaid with the suspended final cladding, which comprises three material types: aluminium sheets, photovoltaic panels, and tubular profiles for ventilation.

The brainwave in the Mohamed VI tower is the EPDM polymer rubber between the curtain wall modules that ensure water tightness in the façade, in addition to the possible movement that occurs in the modules because of structural deformation and adjustment of the double curvature (Figure 12). The brainwave of the biggest project is one of the smallest and simplest elements in the construction system but accomplishes the resolution of the total façade cladding towing to its geometry.