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Sustainability

AIA COTE 2017 Top Ten Winner: Ng Teng Fong General Hospital

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The Green Mark Platinum Ng Teng Fong General Hospital & Jurong Community Hospital is part of Singapore’s first medical campus to combine continuing care from outpatient to post-acute care. The performance-based design, which is based on passive principles, supports resource efficiency, health and well-being.

The sawtooth plan for Ng Teng Fong General Hospital revolutionizes the traditional healthcare model by providing every patient with a window. The team designed the patient bed towers to optimize these aspects of the patient experience. The fluid, dynamic design directly responds to the position of the sun and prevailing breezes.

Seventy percent of the facility (82 percent of patient beds) is primarily passively cooled and naturally ventilated; only 30 percent is air conditioned. Thermal mass, ceiling fans, cross ventilation and exterior shading ensure that the temperature remains comfortable throughout the day, with typical ventilation rates that are higher than in a standard U.S. patient room. Operating suites, imaging, isolation rooms and other critical areas are mechanically ventilated.

Dense vegetation covering low roofs and much of the site form healing gardens, staff-only respite areas and community park space. Vegetation also grows vertically up the building, both in planter boxes and along wires linking floors.

As design and medical planning consultant, HOK collaborated with the Singapore Ministry of Health and a team that included CPG Corporation (prime architect and architect of record) and Studio 505 (design collaborator focusing on building envelope development).

In April 2017, the American Institute of Architects named Ng Teng Fong General Hospital one of the year’s 10 best examples of sustainable design as determined by AIA’s Committee on the Environment. Here is a detailed look at the sustainable design strategies that led to the project’s AIA COTE win.

HEALTHCARE FOR ALL

The hospital CEO’s goal was to create a “hospital without walls,” a healthcare facility that would be for and of the community it serves. Our team designed the campus to support the Singapore Ministry of Health’s initiative to provide high-quality, affordable care to all Singaporeans.

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The design integrates the large public facility into city’s dense urban context, both at grade and one level up (the hospital’s first floor). A public pedestrian thoroughfare with a retail mall traverses the center of the first floor, providing safe, protected passage for users coming from the Jurong East Mass Rapid Transit station. This links public transit to every hospital building, as well as to adjacent shopping and offices. Most of the pedestrian activity happens on this first floor.

Bringing neighbors and shoppers through the campus to access the light rail creates a more transparent, less daunting environment, positioning the hospital as part of the community fabric.

The site features a community park and green roof terraces. An auditorium and training rooms are available for public rental or community programs.

Several hundred community members participated in the design process at critical junctures. Structured events included visits to the full-scale mockups, groundbreaking and topping-out ceremonies.

BACK TO ITS ROOTS

The project reintroduces ecology into an urban, heavily developed region. Two hundred years ago, before it was filled in to make way for an industrial district, a mangrove swamp covered this edge of Singapore. Although mangroves are no longer an option for this site, the design team restored ecological benefits by specifying other native vegetation and a stormwater capture, reuse and infiltration system.

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“We envisioned the hospital as an oasis in the dense city of Singapore,” says Bill Roger, regional director of Healthcare based in HOK’s San Francisco studio. “The design incorporates parks, green roofs and vertical plantings throughout the campus and offers each patient an operable window with views of the greenery. It’s unique for a healthcare facility to offer this much access to greenery and natural ventilation.”

Additional vegetation and street trees line the main roadways, and a jogging trail surrounds the site. All of the plants and trees are native or adapted to Singapore, minimizing the need for irrigation and creating a habitat that attracts local fauna.

CONSERVING WATER

With the city’s limited land mass, water is a precious resource in Singapore. The design team incorporated several water-saving strategies.

The main water-reduction strategy occurs in the HVAC system. The use of natural ventilation and passive cooling for 70 percent of the building significantly reduces water use.

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For the remaining cooling needs, the mechanical system uses NEWater, a pillar of Singapore’s water sustainability strategy. This municipally scaled wastewater treatment system returns reclaimed water to high-grade, potable standards. Because of its low mineral content, NEWater is more effective than standard tap water in the HVAC system and can be used for more cycles before it is discarded.

The design team specified low-water fixtures and equipment to the extent possible within infection prevention requirements. Rainwater is harvested, stored in underground cisterns and used for irrigation in lieu of potable water. No potable water is used for either irrigation or the HVAC system. In addition, the toilets are plumbed to accommodate reclaimed water in the future.

BANG FOR THE BUCK

The Ministry of Health’s capital investment in these sustainability measures is expected to yield significant financial returns.

“By providing patients with access to nature, daylight and natural ventilation, the design dramatically improves the patient experience with only a modest increase in square footage and cost,” says Shiva Mendez, senior medical planner in HOK’s San Francisco office.

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The unique design makes it difficult to compare the building’s costs with others in the region. The additional exterior skin contributed to a higher first cost. The benefits provided by daylight and views to nature will yield operational savings through shorter patient stays, better infection control and staff retention.

The fan-shaped floor plan and high-performance facade create spaces that are comfortable without air conditioning or much electric lighting during daytime hours, reducing operating costs. On the interior, views to nature provided a visual focal point in lieu of expensive, high-end finish materials.

Support spaces such as materials management and kitchens are shared among the general hospital, community hospital and outpatient center. This eliminates redundancies and cuts costs.

Pre-fabricating precast modules reduced construction time and costs.

PERFORMANCE FIRST

An integrated, performance-based design approach led to significant energy savings. The design EUI of 72 kBtu/sf/year represents a 38 percent reduction compared to the typical Singaporean hospital and a 69 percent reduction compared to U.S. hospitals.

“We used detailed computational fluid dynamics models, shading analysis, climate analysis, daylight modeling, acoustical studies and energy modeling to optimize energy efficiency and the patient experience,” notes Roger.

The facade design is unique to each orientation. Custom external shading devices include sliding sunscreens and light shelves. The optimized shading design provides at least 60 percent shading for critical facades and 40 percent for other facades.

In addition to these passive strategies, the mechanical system uses efficient plant-side and air-side equipment, with a target system efficiency of <0.625 kW/ton.

Other energy-saving strategies include:

  • Heat recovery in operating rooms using heat pumps and heat exchangers with runaround coils
  • Use of a chiller plant measurement and verification system 
  • For mechanically cooled spaces, a dual mode switch automatically cuts off air conditioning when a window opens
  • Escalators and elevators are in standby mode when occupancy is low
  • 100 percent of hot water demand is met by solar thermal collectors 
  • 90 kW photovoltaic array 
  • Demand-controlled ventilation
  • T5 and LED lighting
  • Daylight and occupancy sensors 
  • BMS incorporates monitoring, occupancy levels and sleep modes

HEALTHY PATIENTS, HAPPY PATIENTS

“Healthcare research repeatedly demonstrates that providing access to daylight and views to nature improves patient care,” says Mendez. “It also enhances alertness and reduces errors by physicians and nurses. We designed the hospital around these concepts to provide an optimal experience for both patients and staff.”

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Hospitals typically push staff areas into the center of the floor plates. Most NTFGH staff, however, have frequent access to daylight and views. At the patient beds, a portion of the jalousie windows are fixed in an open position to guarantee a minimum air change rate. Patients control the remaining portion.

Although some staff desks are located in the building’s core, most staff either have access to windows or perform functions that don’t keep them at a desk for much of the day. Respite gardens, nap units and massage modules support staff health and well-being. Separate gardens dedicated to patients encourage healing through contact with nature. They also serve as rehabilitation spaces that promote activity and enable patients to relearn mobility.

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MATERIALS MATTER

The team chose building materials based on factors related to durability, longevity, maintainability, health impacts, affordability and regional availability. To select the most sustainable project materials, the team used the Singapore Green Labeling Scheme and Singapore Green Council Certified Product list. Select materials contained high levels of recycled content, including carpet tiles, porcelain tiles, composite timber, cast-in-place rubber flooring and steel.

Use of long-lasting, low-maintenance materials ensures that the building will survive long into the future. The easily cleanable materials help maintain proper levels of sanitation. Low-emitting materials minimize indoor pollutants.

Because Singapore has a limited supply of locally sourced materials, only aluminum curtain walls were available locally. These were extensively used in the facade of the outpatient center and for the hospital podiums. Instead of high-end finishes, the interior relies on interior vegetation, natural light and views to the exterior that provide focal points.

INHERENT FLEXIBILITY AND RESILIENCY

“We designed the hospital to provide a high degree of adaptability to future needs and to withstand natural or manmade disasters,” says Mendez.

The clinic’s administrative floor could function as a clinical floor. With minor changes to the HVAC system, the community hospital could function as an acute care hospital. Single-bed hospital rooms can be adapted into wards with two or four beds. Wards with six beds can double their capacity to 12. The modular clinics allow for specialty groups to easily add or reduce space. Operating rooms are universal, and clinical spaces have adjacent soft spaces that will accommodate future changes.

NTFGH serves as a ground zero emergency preparedness center and supports three modes: peacetime (typical), national emergency (wartime) and civil emergency (pandemic outbreak, natural disaster, mass casualty or chemical attack). A complex labyrinth system prevents bioterrorists from accessing air handlers. The joint basement of the health centers is designed as a highly resilient bomb shelter that can withstand disasters and provide trauma care during emergencies.

With 82 percent of patient beds naturally ventilated and daylit, most of the facility could maintain basic functionality during a utility failure. Additional power demands would be supplied by the photovoltaics, solar thermal system and backup generators.

LESSONS LEARNED

“The design of NTFGH challenges the traditional model of a hospital, both from American and Singaporean perspectives,” says Roger. “While window access is fairly standard in the U.S., inpatient bedrooms are rarely naturally ventilated, passively cooled, fully daylit or able to provide views of vegetation to all patients.”

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Though some Singapore hospitals employ natural ventilation, most organize around double loaded corridors. Air flow may cross one patient prior to reaching another. NTFGH was the first hospital to use a cross-ventilation scheme that allows for high ventilation rates at every patient bed without cross-contamination.

In the one other Singapore hospital that had previously incorporated vertical vegetation, views to this greenery were only available for the few beds closest to the windows. NTFGH extends this benefit to all patients.

This was the first project in Singapore to combine acute care, long-term care, primary care and specialty outpatient care on the same campus. This model has proven extremely effective in improving follow-up care for patients and leveraging staff across the continuum of care. New public hospitals are being planned to follow this model. Existing healthcare campuses are being modified to incorporate all types of care.

Related: AIA COTE 2017 Top Ten Project Winner: NOAA Daniel K. Inouye Regional Center