Summary--The
specifications of the Hotel Me project required a particularly innovative
facade design. This article describes and explains the unusual solution
developed by the façade
designers, in answering the specification’s requirements.
1. Introduction
One
of the Engineer’s tasks is to execute the Architect’s design. Such a statement depicts
the work done for the façade
of the Hotel Me designed by Dominique Perrault and his design team. It is located
at the junction of the Avinguda Diagonal and Pere IV Street in Barcelona. The
building is a skyscraper of 117 metres in height (Photograph 1). The geometry is reminiscent
of a number four, inspired by the stone heads of Easter Islands, with and
adjacent 25 metres tall cube shaped building.
2. The Façade
2.1. Architecture
The façade is a unitized curtain wall
system formed by several differing modules, combining heights of 2.6 and 4.6m,
forming a saw tooth shape. Once installed, each unit incorporates the
waterproofing, the fire, thermal and acoustic insulation, and moreover the
internal architectural design for the room.
Each of the rooms is
formed by four panel types (Photograph 2 and 3). Two of them are ‘opaque’ type being a triple skin
4.6 m high formed by an external laminated glass, a stainless steel metal
shaped sheet sited in the air gap and a inner insulation sandwich panel with
stainless steel bright polished as per design for the room.
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| Photograph 1. View from Avinguda Diagonal |
Another type of panel
is named the ‘filter’ being 2.6m high and allowing solar radiation to pass
through a triple skin formed by two panes of glass with a stainless steel
perforated shaped sheet fitted between the glass. The inner skin is accessible
for maintenance.
The last panel is
named ‘transparent’; being a window 2.6m high.
There is a fourth
type of panel placed at the emergency stairs providing ventilation. This module
is clad with vertical louvers of bright polished stainless steel.
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Photograph 3.
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2.2. Engineering
The frame of the
unitized curtain wall panel is formed by two layers of aluminium joined through
a low conductivity material that breaks the thermal bridge.
The waterproofing of
the union between the transom and mullion is resolved through a waterproofing
sealant.
Each curtain wall
module is formed by two panels including hooks to be hung on the brackets fixed
to the concrete slab (Photograph 4).
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Photograph 4.
Typical module clad with unitized curtain wall 7.2m high and 1.2m wide, covering two rooms. The panel above is transparent and the panel below is opaque.
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One of the
specification’s requirements was to provide the fire insulation at the gap
between the curtain wall and the slab, including the fire insulation in the
curtain wall module. In order to achieve this a rock wool panel was added in
the module in front of the slab, and the joints were sealed with fire rated
materials. Once the solution was designed, it was tested in a European notified
laboratory, achieving 92 minutes of fire resistance.
The
acoustic performance of the whole room with the curtain wall panels attached
was also tested. The acoustic insulation achieved was 39 dB, being higher
than the 30 dB required by the standard.
The
waterproofing is achieved through the contact between the bubble gaskets fixed
continuously through the aluminium frame (Photograph 5).
The
filter and opaque panels include an air gap, where the stainless steel bright
polished bent sheet is inserted. The particular design of the bent sheet
required them to be bent through a manual process.
The
opaque modules are cladded with the bright polished stainless steel as the
finish for the room in the inner skin. This is fixed through an aluminium cover
cap.
The
external glass is laminated transparent float, structurally bonded to the
aluminium frame. Due to the requirements of the Quality Control team,
additionally a cover cap was used for fixing the glass mechanically onto the
frame.
The
internal glass, an insulated low emissivity unit, is present in the transparent
and filter modules.
The
façade is resolved and
interfaced with the perimeter elements such as vertical dividers, ceilings and
finished floors. The acoustic insulation (Photograph 7) and fire insulation elements (Photograph 6) are
executed in situ. Subsequently, the finishing trims are installed.
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Photograph 5. View of the union of two modules. Note the broken thermal bridge, the bubble gaskets, the waterproofing sealant at the union between transom and mullion, and the cover cap as a mechanical fixing component.
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Photograph 6. The technical design for the composition at the dividing line between rooms that achieves 45 dB of acoustic insulation.
Photograph 7. The technical design for the horizontal fire insulation composition covering the gap between module and slab.
2.3.
Execution
The
main activities for the assembly, brackets and modules, were carried out from
the outside the building due to the particularities of the project, as
described below:
The limited
thickness of the floor, did not allow the bracket installation on the slab
surface. It was consequently installed on the slab edge from the outside of the
building.
The design of the main structure of the building, with
concrete walls as divisions at the façade
facing the sea and the metallic structure at the façade facing the mountains, did not enable the use of any kind
of equipment for horizontally shifting the modules along the floor plan after
unloading the prefabricated units. The panels had to be individually lifted up
to each storey in order to be installed. Hence, a free surface on the slab was
needed, in order to move, erect and install these panels.
Therefore,
a customized auxiliary system was designed to resolve the conflict with the
elements in the interior of the building to allow installation from the
outside, optimising safety, convenience and performance.
This kind of track running continuously
through the full perimeter of the building, as it was not feasible to work from
inside due to the interference with the structure of the building. This rail
supported two cradles and a mini-crane (Photograph 8).
The cradles were allowed to move
horizontally and vertically throughout the entire façade. The cradle included
all the elements to carry out the works efficiently. The mini-crane could hoist and
install the curtain wall modules (Photograph 9). It was designed to allow a maximum load of
1100kg. It was possible to hoist a curtain wall panel from the ground floor to
the 32nd storey, and then it could be horizontally moved to the
final position, aligned and installed (Photograph 10).
The vertical displacement of the
module was guided by a tensile cable system the same height as the building.
The method statement for the
assembly was based on the shifting of the modules to the package, the
dismantling of the package to the individual modules, the hoisting by the mini-crane
and the guidance of the tensile cable system. Once the module reached the
respective storey, it was horizontally moved to its position, where it was
aligned by the jacking bolts at the hook bracket, ensuring the contact between
the bracket and module.
The daily average performance was
70 square metres, with the wind being the main issue. The daily performance,
considering only the net days worked, was 90 square metres.
The quality control plan was
rigorous, inspecting the welding and torque settings of the brackets, module
tolerances to meet the requirements of the project and to achieve the
environmental performance designed.
With regard to the dimensional
control, a survey of main structure was periodically carried before analyzing
and making the decisions on the position of the façade, whilst absorbing the
misalignments of the structure.
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Photograph 8. The customized auxiliary system to install the modules. The system was installed on the 32nd storey through a cantilever beam. Note the vertical displacement of the module.
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| Photograph 9. Mini crane, lane system and cantilever beams as a structural system. |
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| Photograph 10. Unitized curtain wall module during horizontal displacement at 31st storey. |
3. Conclusions
Without any doubt, the unitized curtain wall
system, minimized the installation works on site, improving the delivery times
and the quality of the final product, in comparison to an in situ façade
system (Photograph 11).
The success of such a particular façade was based
on the façade being defined four months prior to being erected onto the building,
rigorous planning and successful cooperation among the staff of the façade company
and main contractor, obtaining the approvals of the consultants and architects
to carry out the façade works properly coordinated with the rest of
subcontractors.
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| Photograph 11. View of the building from Pere IV Street.
Note 1: This article has been already published in journals of architecture (Revista Hueco Arquitectura; AFL Arquitectura de Fachadas Ligeras; Infodomus; L´Informatiu del CAATB). The original version is posted in this blog in the following link .
Note 2: The building was named as Hotel Sky during the project execution.
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