Images Courtesy of HKS / Wingler & Sharp

Balfour Beatty

and

McCarthy

balfourbeattyus.com

mccarthy.com

HKS Architects

Wingler & Sharp

Architecture

Carl R. Darnall Army Medical Center will be replacing Fort Hood’s current hospital adjacent to the site. The new hospital is zoned to minimize confusion among patients, as well as maximize effective communication between departments. The spatial design will allow soldier’s families to easily travel about the hospital without confusion. The women’s center is in the northeast, patient and visitor entrance is in the north, the outpatient entrance is on the west side, the emergency entrance is on the east, and the service entrance is on the south side. On the east side is a patient bed tower with an office space on the sixth floor which allows for future expansion. The first floor consists of the departments with frequent visitors such as the women’s health care, pharmacy, radiology, retail and dining, all of which are grouped around a healing garden which maximizes the natural light into the building. The entire building is over 900,000 square feet with six floors above ground and a basement, and floors 1-6 consist of interstitial building spaces above. The IBS floors allow for maintenance to wheel a cart around and service the building systems without disturbing the patients below.

Zoning

Zoning is not available at this time. The hospital is a replacement for the current hospital adjacent to the site. It is located on an army base; there are no historical requirements of the building.

Codes

• Unified Facilities Criteria (UFC)
• International Building Code: IBC 06
• International Mechanical Code: IMC 06
• International Plumbing Code: IPC 06
• National Electric Code: NEC 08
• National Fire Protection Association: NFPA 70, 101, 109
• International Energy Conservation Code: IECC 06

Building Enclosure

Carl R. Darnall Army Medical Center is a cast in place concrete framed building. The exterior facades consist of precast concrete paneling and stone paneling as well as metal panels. The wall system consists of brick veneer on two layers of concrete tied together by rigid insulation thus making a wall of over six feet wide. The masonry paneling is water resistant, very durable, and resistant to freezing/thawing. The glazing consists of curtain wall, strip windows, and individual windows. Low-e coated insulated glass is used for all of the windows, along with thermal barriers. An external sunshade runs along the individual windows of the patient rooms in order to cut out harsh summer sun rays.

Image Courtesy of HKS / Wingler & Sharp: Partial West Elevation (Emergency Entrance)

The roof is mainly a 10” two way cast in place concrete slab with insulation and PVC membrane which keeps the moisture out of the roof structure, and minimizes heat gain. Parts of the facility also have a vegetated roof to maximize sustainable aspects of the roof while reducing run off storm water. The vegetated roof consists of a fluid applied waterproof membrane followed by root barrier, polystyrene insulation, water retention mat, filter fabric, and vegetation. It was designed in certain locations of the building to increase the sustainable aspects of the roof.

Sustainability

The hospital will gain LEED Gold certification upon completion. The building enclosure helps improve sustainability by using regional material for the façade, high performance glazing with solar shading and the roofing uses dark PVC to meet the LEED requirements for reflectance as well as vegetated roof to reduce heat island effect. A few mechanical components include heat recovery chillers, recovery cooling tower blowdown water for irrigation, and energy recovery through enthalpy wheels.

Electrical

Emergency power is provided to the building by two 480 V, 3 phase emergency power class generators. The CUP receives 12.47kV from primary feeders which then steps down to 480/277, 3 phase with transformers. Two pairs of 480V, 3 phase diesel generators provide emergency power for both the CUP and the medical center. The medical center generator provides emergency power to the life safety and critical branches in the hospital.

Lighting

The medical center has recessed lighting with more luminous lighting in the medical rooms. The lighting throughout the medical center has a CCT ranging from 4100K for offices to 5000K for surgical and patient rooms, and a CRI of mainly 86 ranging to 90 for surgical rooms. Most of the lighting is T8 fluorescent lamps with instant start ballasts.

Mechanical

A central utility plant, located off site, houses four 1,250 ton centrifugal chillers and four 11,600 MBH steam boilers. The base loaded 200 ton heat recovery chiller provides chilled water during the winter and it preheats the returning heating hot water. Twenty five air handlers provide 100% outside air for the hospital with enthalpy wheels that recover heat from the general exhaust air. The chilled water system provides a supply temperature of 44°F to the air handlers, fan coil units for electrical and telecom rooms. The building uses hot water produced by four gas fired steam boilers. The heated hot water system provides a supply temperature of 140°F. Above each floor is an IBS floor which allows for easy maintenance of the equipment for building services.

Structural

Concrete beams were designed for redundancy in order to protect the medical center from progressive collapsing. Steel braced frames on exterior or interior are the main component of the lateral system. The floors designed for high activity for medical procedures are designed as a 10” two way slab, and the 6th floor is designed as an 8” two way. The IBS floors are designed as 3”x18 GA composite deck with concrete topping. The hospital floor beams are designed to resist progressive collapse.

Construction

The medical center is a joint venture between Balfour Beatty and McCarthy, with a Design-Build contract. The projected date of completion of the medical center is February of 2015. The overall rough cost of the medical center is just over $900 Million.