New Changi Facades for Singapore

High Performance Engineering in Glass

New Changi Facades Hugh Dutton Changi Airport is the front door of Singapore, and the facility is continuously modernized in the image of the garden city state itself.

T2 Departure Facade

Changi has for many years been voted the world’s best airport in user surveys, and anxious to remain top in the context of other massive airport modernization projects, such as Osaka’s Kansai, and Hong Kong’s Chep Lap Kok, the Civil Aviation Authority of Singapore CAAS) embarked on both an ambitious new terminal T3 as well as the upgrading of existing T2.

The new T3 building consists of a main hall measuring 300m x 200m with linear concourses extending north and south. The local architectural team CPG, assisted by SOM of New York, collaborated with Hugh Dutton Associates for the design of the facades of the building.

The HDA practice were also appointed on the T2 refit, designed by Gensler of San Francisco, in collaboration with the local architects RSP.

T3 Departure Facade

Related Oppositions The occasion of contributing to the facades of both major terminals provided HDA with an opportunity to create a thematic consistency for the façade designs between the two buildings, done by different architectural design teams.

Both façade designs strive to express the CAAS’s objectives of a contemporary image combining the themes of appropriate and ecological technology with transparency.

Both designs exploit structural glass and innovative solar coatings and use innovative glazing support systems consistent with the different architectural contexts for each. T2 is a composition of fluid curving geometries, while T3 is a sobre and minimalist composition of orthogonal surfaces and design with light. intelligent glass solutions

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High Performance Engineering in Glass

For T2, Gensler’s redesign included a reconstruction of both the principal departure hall facades creating a series of glass curved leaf shape canopies as well as a new airside façade for an extended waiting lobby with views onto parked aircraft and runways beyond.

New ceilings in the departure hall are dominated by gently curved glass lights in bays over each check-in island. The airside lobby façade is a bowstring façade inclining toward the airway.

For T3, the facades concept is minimalist transparency and energy compatibility. The design for the new terminal involves a high performance roof that filters daylight into the space for the main hall.

Sun path in Singapore

The massive roof has a thousand actively adjustable skylights with suspended light reflectors that respond to the changing daylight conditions. In the context of this expressively designed light filtering system, the facades protect the users from glare and low angle sun as well as provide the required transparency.

Both designs face the familiar challenge of modern façade design of resolving the contradiction of maximum transparency and solar protection.

Equatorial Sun Singapore, located on the equator, has its own particular hot and humid climate and solar exposure. The sun’s path is therefore at its most zenithal with alternating but equal exposures for north and south facades in the mid-season equinoxes. Protection is therefore primarily required for east and west sun.

Changi airport’s orientation is along a north/ south axis and is such that the terminals face each other with east and west exposed main departure lobby facades. Both have airside facades facing the runways again to the east and west on the opposite sides. Protection must be provided for this morning and evening low sun on these main facades for both buildings. T2, facing the west, uses deep leaf shaped canopies, while T3 has a very deep roof overhang. Airside, both terminals have operable louvers that open and close according to solar exposure.

T3 Cable net The frontispiece of T3 is the Main Building departure hall cable net façade. An exercise in discretion and transparency, it consists of a simple 34

Cable clamp glass fixing detail

Cable net and glass deflection analysis

orthogonal grid of cables tensioned vertically between the roof and the ground slabs as well as laterally between the roof support columns with glass panels clipped to custom designed cast cable clamps.

The cable net is a high deflection system, that depends on the cable deflection to develop resistance against an applied wind force. The net will deflect up to 30cm in maximum conditions, that were simulated on a full scale on one 15m wide x 18m high typical bay of the façade measuring prototype .

The suppleness of the cable system requires specific attention to the fixing details that must allow the movement and deflection of the glass, whilst still firmly fixing the glass in place. Rather than use bolted glass, it is clipped using more discreet patch fittings with EPDM rubber bearing pads bonded to the castings. intelligent glass solutions

High Performance Engineering in Glass

" The massive roof has a thousand actively adjustable skylights with suspended light reflectors that respond to the changing daylight conditions" The cable net façade is the only single glazed façade, for reasons of architectural transparency.

Insulated glass edge seals were considered unaesthetic and incompatible with a high deflection support system.

T2 Canopy and glass fins T2 has it own distinctive frontispiece; a transparent composition of the leaf glass clad canopies and glass fin façades beneath them.

These prominent canopies are supported on A bowstring truss in transport

T2 Departure façade glass fin

tapering sections of structural steel with tubular ribs. They are glazed in translucent fritted glass to cut direct sun rays, but provide the desired luminance in the departure hall.

The façade fins are fixed as cantilevers from the canopy tie structure above, half inside half outside the glass façade plane to minimize their penetration into the space and visual impact.

Insulated panels are fixed to custom cast clips suspended from thin metal straps concealed behind the insulated glass seals either side of the glass fins. intelligent glass solutions

These castings are in the same bead blast stainless steel finish as those of T3 and use an identical EPDM patch cover fitting. The only identical piece on both facades is this small, and quite critical, component.

Bowstring Truss The 70000 m2 of other typical facades of both terminals are in double glazing to optimize energy performance. These insulating glasses have more strict stiffness criteria for the supports to protect their sensitive edge seals.

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High Performance Engineering in Glass

Sun shading applied to bowstring truss A grid of steel framing provides continuous edge support. However the spans of the facades vary considerably, from one storey heights in the concourse wings to some double height spans up to 18m in the departure hall of T3.

For economic viability of such a large project, optimizing the façade components is important, so one section dimension of 60mm x 120mm was fixed for the entire façade system. It is capable of spanning on its own the single storey heights, but for the taller spans, a bowstring tie system is introduced to provide the necessary inertia.

The ties are fixed like spreaders either side of a sailboat mast using cast struts with standardized end fittings for the tie rod connections. The 60 x 120mm section, analogous to the mast itself, forms the compression spine in the system and provides support for the glass plane.

This same bowstring spreader stiffening system conveniently provides a support for the sun protection louvers. The louvers are perforated metal blades fixed to a tube axle that is connected to the tips of the spreaders.

Glass – Distortion, Energy, Glare and Security Consistent issues and parameters are shared for the glass products themselves on both terminals. The client was particularly concerned about optical clarity given distortion and delamination problems related to the use of fully tempered glass.

Additionally CAAS had lived their own problems with spontaneous breakage on other glass structures in the airport. Exploitation of glass’s structural potential for architectural transparency 36

T3 Bowstring facade

" Both designs exploit structural glass and innovative solar coatings and use innovative glazing support systems "

required the use of tempering to improve mechanical performance, so the design team limited the use to heat strengthened products where the distortion, though not avoidable, can be reduced.

Energy performance is critical too for a client with a conscience for ecology. Protection is required for shading and for limiting heat gain. All glass is slightly body tinted to achieve a degree of protection and shading and high performance UV radiation selective coatings were applied to all insulated glass panels.

Though luminous transparency is desired at the airport to express an openness it creates problems for users if glare makes reading computer monitors with flight information difficult.

To diminish glare grey frits are applied on all

facades. Whilst vision glass at eye level is fully transparent, the frit is applied in bands of gradually increasing density up to the roof level.

All glass is laminated, to limit security risk and maximize safety against falling glass in the case of spontaneous breakage.

Passive Chameleon The facades of both terminals attempt to provide transparency and views of the sky from indoors, and views inside the building at night, whilst still protecting from the solar radiation in the day.

Like a chameleon, the façade changes its nature at the different times of the day through this intelligent glass solutions

High Performance Engineering in Glass

T2 departure night and day

T3 Departure night and day

combination of the body tints, fritting and perforated louvers.

All these treatments are transparent, but filter the light in response to the energy requirements.

The generous overhangs of both entrance facades - the large oversailing main hall roof on T3, and the leaf canopies of T2 - provide sufficient shading to the entrance facades, which combined with strong lighting within the departure halls inside manage to maintain a significant transparency through to the life of the airport and the abundant indoor planting in each which was the objective of both CAAS and their architect teams. intelligent glass solutions

Credits: Client: Civil Aviation Authority of Singapore T2: Architects: Gensler (San Francisco) & RSP (Singapore) Faรงade Design: Hugh Dutton Associates (Paris) General Contractor: Takenaka Faรงades Subcontractor: Mero T3: Architects: CPG (Singapore) with SOM (New York) for concept design Faรงade Design: Hugh Dutton Associates (Paris) General Contractor: Shimizu Faรงades Subcontractor: Permasteelisa

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High Performance Engineering in Glass

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