JEWEL CHANGI AIRPORT

Jewel Changi Airport

Jewel Changi Airport With contributions by: Liew Mun Leong Chairman, Changi Airport Group Lee Seow Hiang CEO, Changi Airport Group Moshe Safdie Lead Design Architect, Safdie Architects Jaron Lubin, Charu Kokate Principals, Safdie Architects Adam Greenspan Lead Landscape Architect, PWP Landscape Architecture Craig Schwitter, Cristobal Correa Lead Engineers, BuroHappold Patrick Bellew, Meredith Davey, Henry Woon Environmental Designers, Atelier Ten Martin C. Pedersen Architecture Critic Sam Lubell Editor

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Creating a 21st-Century Glasshouse Atelier Ten Patrick Bellew Meredith Davey Henry Woon

Environmental Designers

Green Singapore

In 1967, Prime Minister Lee Kuan Yew presented his vision of Singapore as a “City in a Garden,” a goal that has driven its physical identity ever since. Singapore’s tree-lined boulevards, large parks, sky gardens, green connectors, and many other landscape devices now define a place where there is an almost continuous physical connection between man and the natural world.

In addition to providing Singapore a clear identity as one of the world’s greenest places, the green cover that makes up some 47 percent of its area limits much of its equatorial sunshine and reduces its temperature. It also absorbs pollutants, filters particulates, and provides oxygen.

With this profound impact in mind—along with the enthusiastic support of Moshe Safdie, who clearly had something pathbreaking in mind—it seemed completely appropriate that Jewel Changi Airport, the new gateway to Singapore, should represent the very best, and greenest, that the country has to offer.

A New Kind of Glasshouse

The history of conditioned planting under glass consists mainly of buildings that consume very large amounts of energy. Glass is generally not a great insulator, and the greenhouse effect is an immutable reality. Victorian-era glasshouses, such as those at Kew Gardens and the New York Botanical Garden, were single-glazed with cast glass to maximize light and solar gain, requiring huge amounts of resources to heat and cool. Modernist versions, like the Climatron in St. Louis, introduced conditioning innovations like “swirling” air flow systems, which made conditions more comfortable, but still couldn’t completely solve the energy conundrum. Recent advances have had more success, like the U.K.’s Eden Project, a bubble-like structure in Cornwall, England, that balances performance and sustainability through advanced building management systems, an insulating, double-layered ETFE skin, sustainably sourced materials, and a renewable energy program using rooftop photovoltaics and water harvesting.

At Jewel Changi Airport, our team needed to perform an especially challenging balancing act: introducing natural light, showcasing nature, and providing constant thermal human comfort in terms of temperature, humidity, and air movement, all while minimizing the building’s energy demands. We undertook a considerable amount of research to get this balance right, while ensuring that the systems in the space would be as concealed as possible so visitors would not be aware of the technology and equipment keeping them comfortable.

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Construction of the Level 1 floor slab includes integrated chilled flooring. The Forest Valley planters above have integrated displacement cooling systems hidden from sight. Rain Vortex (center) and train bridge (right) assembly are well underway.

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Modeling Daylight

Modeling air speeds (top) and temperatures (bottom) to inform the design before commencing construction

Mapping daylight levels and solar exposure for the Forest Valley. Generating these maps allowed the landscape team to determine appropriate daylight levels for each garden’s plantings.

Resolving the competing demands between heat and light was the basis for many months of discussion between the design team and client. The main issue was that plants typically need higher light levels than people, which introduces elevated levels of unpredictable solar heat. Our façade optimization therefore sought to ensure that light levels would vary in different parts of the building based on planting locations and palette, while still minimizing the loads on conditioning systems.

Using a combination of bespoke ray tracing and illuminance prediction software linked to the architect’s 3D BIM model, we modeled the light coming through each triangular cell of the grid shell roof for each hour of the year. This modeling technique facilitated greater design and engineering flexibility, and allowed us to evaluate many different glazing materials and surface coatings in terms of energy demand and use.

The glass coating that was eventually selected for Jewel admits 62 percent of the sun’s energy as visible light, while allowing only 33 percent of that energy as heat. A frit pattern, which creates the building’s varied external appearance, was applied in different densities to reflect broadband radiation in areas where light is less critical. Where daylight is not required for plant growth, such as the event plaza, fritting and motorized shading devices further reduce air-conditioning requirements.

Apart from comfort implications, the ability to limit solar heat gain while still delivering high daylight levels was vital to reducing the airconditioning requirement in the indoor garden, which in turn would reduce servicing needs, plantroom space, and energy use.

Our collaboration with PWP Landscape Architecture was particularly important to this process. As the daylight analysis produced an understanding of the available light in particular areas, we took an iterative process to asses appropriate plant selections and landscape responses. Conversely species that required higher light levels were accommodated by adjusting the surface properties of the glass to shine more light into these areas.

Thermal Comfort and Systems

While plants are mainly affected by the overall energy they receive from the sun, humans are more concerned with instantaneous conditions, aka comfort. To maintain well-being while minimizing energy demand, our intent was to only condition areas that people would inhabit, and to work with the architectural forms of the space to optimize the semi-natural air flows from features like the Rain Vortex.

Realizing the Dream / Environmental Design

In the tropics, manually operated punkah fans are still widely used in non-conditioned spaces, while in most conditioned spaces it is normal to limit air movement because of concerns with cold air and drafts. We developed something of a hybrid in Jewel, creating regular zones of higher-than-normal air movement, which give the impression of a semi-outdoor environment and provide additional cooling effects to offset exposure to solar gain.

Jewel’s air movement is mainly achieved by supplying cool, dry air into the space at low levels, but at a comparatively high velocity, producing an effect akin to a light breeze. In addition, the majority of the hard floor surfaces have chilled water piped through them.

The conditioning system relies on heat from the space stratifying and rising to higher levels (plants are more forgiving of heat than humans), confining the cooling to the occupied zone.

A series of lab experiments, using a radiant heat source to replicate the effects of solar gain, were conducted to confirm what would constitute acceptable air velocities inside the space. The tests were calibrated by taking thermal readings of visitors inside the flower dome at Gardens by the Bay, then recreating those results inside the lab.

The Rain Vortex waterfall at the center of the building provides a minor cooling effect on the space through direct evaporation. But its disruptive air movement proved to be a complex challenge for our hybrid displacement air system. Our computational fluid dynamics tests showed that its falling water droplets would pull stratified hot air from the top of the space down to the lower levels, creating extra heat and humidity around its base. Subsequent modeling showed that a continuous glass balustrade around the base (which was installed) would serve to redirect the air vertically and prevent the disruption to the air in the surrounding areas.

Skytrain Tunnels

One of the most striking features of Jewel is the Skytrain that travels through the building, over the Forest Valley. In the original design the train’s track was enclosed in a glass tube, intended to prevent cool air from leaking outside. However, the glass tube obstructed views of the garden and vortex and there was a strong push to eliminate it.

After extensive analysis the team opted to incorporate four sets of interlocked fast action doors—similar to those used for vehicle access to cold stores in warehouses—into the tunnels approaching the entry and exit to Jewel. These operate sequentially and rapidly to minimize air leakage. The Skytrain slows on entry to minimize the piston effect of air being pushed in front of the train and dragged out behind it.

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Jewel is located at a point where trains arriving from other terminals cross over, meaning they tend to arrive from each side simultaneously. Each train pushes a small amount of air into the building, but at relatively low velocity. This warm air is then sucked back out by the train going in the opposite direction out of the building. Extensive computational fluid dynamics (CFD) simulations demonstrated the effectiveness of this proposal, helping it achieve local Building and Construction Authority (BCA) approval despite its variance from normally accepted standards.

As the Skytrain approaches Jewel, passengers will have a good view of the 463kWp-rated 1,381-panel solar array that has been installed on the train station roof—one of the two arrays that have been installed as part of the Jewel project with output totalling 830kW. This makes it one of the largest solar energy arrays in Asia. With the combined energy efficiency measures and this renewable energy initiative, Jewel has achieved a Green Mark Gold+ environmental rating from the Singapore BCA. Jewel is truly a building of today, designed using the very latest in digital modeling to predict with a high degree of certainty how its spaces will perform under all conditions. With the challenging environment of Singapore it would be unthinkable to build such a colossal public space for people and plants without having a very good idea of its comfort level. The techniques used to model and predict these conditions relied upon the physicists at Atelier Ten, a great deal of computer power, and instincts cultivated from years of experience. This is the essence of modern interactive design— instinct, analysis, and collaboration going hand in hand.

This newest generation of glasshouse advances the typology’s legacy, providing optimal comfort and daylight while minimizing energy consumption through building envelope optimization, air movement, air-conditioning, energy recovery systems, and renewable energy. All while making the systems more or less disappear from view. It’s a far cry from the European botanical glasshouse of the past, where the maintenance of plants was all that really mattered.

As a new centerpiece to the world’s best airport, in arguably the world’s greenest city, Jewel represents a huge investment in the belief that man is never happier than when he is comfortably immersed in and awed by nature. With the opening of this extraordinary building, airports will never be quite the same again.

$45.00 [USA] £35.00 [GB]