Rx for Hospital Design: Models & Meetings
When Turner Construction Co. introduced business information modeling (BIM) for building the new University Medical Center of Princeton, it immediately inspired a medical metaphor for the owner: brain imaging technology used by neurosurgeons.
Barry Rabner, president and CEO of Princeton Healthcare System, the owner of the Plainsboro, N.J.-based medical center, compared BIM to how neurosurgeons inject blood vessels with dye and rotate images of the brain on an axis. “As the owner we wanted to keep costs as low as possible while maximizing usable space,” he says. “BIM helped reconcile those needs.”
That was only the beginning of the collaboration process involved in building the 638,000-sq-ft medical center, a replacement for a nearly 100-year-old hospital. Early on, Princeton Healthcare System medical and design officials traveled around the country to evaluate features of some of the best new hospitals. They brought those ideas to the table after choosing Turner as construction manager for the $340-million project. Construction team leaders and subcontractors met weekly for eight months at an onsite smart room to hammer out challenges and go over plans.
The medical center will serve as the hub of a 171-acre health campus located 2.5 miles from the center of Princeton. It will include the seven-story, 238-bed hospital, an attached medical office building, an education center, a skilled nursing and rehabilitation facility, and a 32-acre public park.
HOK, New York, designed the hospital interior while RMJM, Princeton, served as the construction documents architect. Completion is expected by March 2012, three years after groundbreaking.
Designing the hospital's curved bed-tower with its structural grid took a “proactive and creative approach" due to the geometry of the building, says Dennis Mordan, engineering operations director at Philadelphia-based engineering firm O'Donnell & Naccarato. “Coordination of the structural framing design and fabrication with geometry that left no identical connection was extremely difficult,” he says. “All beam-to-column connections are skewed.” To allow for patient rooms of the same width in the curving building, the grid lines were positioned on tangents off the circumference of a circle.
“You would think the geometry of the tower is a radial with each column line forming a radius in a circle, but actually each column line formed a different tangent of a 300-ft circle and each had a different rotation angle,” Mordan says.
The use of 3D modeling helped identify solutions to problems, greatly reducing errors on the job, Mordan says. O'Donnell & Naccarato shared the bed-tower's difficult geometry directly with Cives Steel Co., the Roswell, Ga.-based steel fabricator, by delivering a Revit model that was used to form a 3D fabrication model. “By necessity, we had to do 3D modeling since standard orthogonal connections could not be used because of the building's geometry,” Mordan says.
Cives made suggestions and tweaked its fabrication model. “They welded tab plate connections instead of angle connections at the appropriate angle to accommodate for lack of right angles,” Mordan says. “The difficulty here was that every connection was different.”
The bed-tower also posed unprecedented challenges for the MEP team, since piping had to be notched to allow systems to follow the curvature of the building, says Tim Krawetz, vice president with Syska Hennessy Group, New York.
To work through the design challenges, team leaders and subcontractors studied 3D models during foundation and steel erection construction of the medical center.
“We uploaded the model, reviewed clash detections and worked out hits with individual subcontractors before signing off,” says Greg Ryan, senior project executive at Turner.
With no x, y coordinates in the hospital bed-tower, “we had to lay out the walls, ductwork and piping systems from a fixed, known point using Total Station, an electronic/optical instrument used for surveying,” Ryan says. “GPS was needed because we did not always have line of sight on the intended layout point, due to obstructions such as columns or vertical ductwork and piping systems.”
One congested area of the basement, where three sectors of the building converged with a vertical shaft, required months of trouble-shooting, Ryan recalls. “It was difficult to layer all the pipe and ductwork into that space on 2D design drawings, but once we put everything into a 3D model we could show the design engineer that the 2D configuration couldn't fit three dimensionally into the space,” he says. “Since we couldn't lower the ceiling, we had to create another vertical shaft to move systems away.”
Many green design features were incorporated into the building, including environmental control systems for lighting and temperature and extensive use of daylighting and solar shading to reduce energy usage.
“We conducted an analysis of the best shading for summer that would also allow light in for winter,” Krawetz says. Using Ecotect software for exterior shading analysis provided a stereographic chart that gives the position of the sun at different latitudes, depending on the time of year. This assisted with determining proper placement for the fixed solar shading blades.
Syska and Hennessy also created an eQuest energy model for the building. For the 600-ft-long south facade, the software calculated $228,000 in operating savings per year, Krawetz says. “We had many design charrettes with the owner and even considered putting in a wind turbine, but there wasn't enough wind,” Krawetz says. “He wanted practical results.”
Incorporating LEED specifications into the hospital's design made sense both businesswise and for the community, but the owners opted not to go for certification due to the high cost, Rabner says. “We would rather take that money and buy a new MRI,” he says.
The site also includes a cogeneration power plant, developed by NRG Energy, a wholesale power supplier in Princeton. It will generate 100% of the medical center's heating, cooling and power and is expected to reduce energy usage by 35%, Krawetz says. Construction of the cogeneration plant is expected by mid-August. It is expected to be operational by mid-October.
The central utility plant became operational last September and is providing chilled water and steam to the hospital for cooling and heating during construction. In addition, construction of a thermal energy storage tank, which will contain about a million gallons of chilled water for cooling, is scheduled for completion by late October.
Guy Molinari, senior vice president at Voorhees, N.J.-based Concord Engineering, the contractor managing engineering and installation of the system for NRG, says the plant will use a 4.6-MW Solar Mercury 50 gas turbine and heat recovery steam generator (HRSG) that generates electricity and produces 24,000 lb per hour of steam for heating. The HRSG is matched to back-up boilers to provide additional steam during colder winter months.
The efficiency of cogeneration is 65%, compared with only 33% for central energy plants found at most hospitals, Molinari says.
On the design side, HOK relied on evidence-based design, which seeks to improve patient outcomes by creating an environment designed to reduce stress, enhance safety and promote healing.
For example, for more efficient treatment, the hospital now uses a 64-slice CT imaging procedure that requires less space and turnaround time than a heart angiogram, says Chris Korsh, principal at HOK.
Rabner calls himself an actively involved owner who once “viewed the building as a container for people and equipment, but then realized the hospital structure was part of the solution to improving patient outcomes.”
To avoid the spread of infection, for instance, the owner opted for 100 outside air ventilation systems with energy recovery to capture heat from discharged air in the operatory suite, the emergency department and the bed-tower.
Healthcare System officials looked at 1,200 research projects and visited many hospitals with the goal of integrating best practices to help reduce infections, falls and operating costs. “I think we have done things right, but the real answer will come three years after the hospital opens,” Rabner says.
Upon entering the triple-height atrium space at the front of the medical center in Plainsboro, “visitors can easily see any area they need to visit,” Korsh says. Easy navigation is a central goal of the architectural design of the hospital, with the grand concourse creating a circulation spine for the whole building, he says.
“The design was intended to help people find their way easily, minimize distances traveled by patients, visitors and staff, and to help patients feel safe, less stressed and welcome,” says Rabner, who uses his 89-year-old mother as a model to test the suitability of the hospital's design and services. “This sets the bar very high,” he says.
