Case Studies: Curtain Wall Technology

Problems solved with innovative modeling
Katy Devlin and Norah Dick
August 24, 2018
COMMERCIAL, FABRICATION : SOFTWARE


The TWA Hotel at JFK Airport features a robust curtain wall for maximum sound control. A comprehensive acoustic modeling and simulation process was used to determine the best-performing and most cost-effective glass and framing systems. Photos by Max Touhey.

The advent of building information modeling, or BIM, and related next-generation modeling technologies, has transformed the way buildings are designed and built. 3D computer models have paved the way for more ambitious designs with complex geometries and multiple system types. Digitization of design has introduced new levels of collaboration among project players. And shared modeling tools have increased performance measurements and improved efficiencies. 

“With the modeling that we can achieve today, the sky is the limit in terms of performance, complexity and geometry,” says Peter Corsini, senior designer at Fabbrica.

This article presents two case studies that demonstrate the wide range of modeling solutions available to project teams. In one, a design team relied on acoustic modeling and simulation to develop a quiet and cost-effective building envelope. In the other, the project team looked to 3D laser measuring tools to model onsite conditions, greatly increasing accuracy and efficiency on a complex wall and canopy job.

These case studies demonstrate just two examples of how modeling technologies are transforming design and construction. To share additional case studies, write to Editor-in-Chief Katy Devlin at kdevlin@glass.org.  

Case Study 1-Simulated Sounds at TWA Hotel

Acoustic modeling dictates façade design at JFK Airport hotel

Right: The project team recorded noise levels at various site locations.

In late 2016, the TWA Hotel design and construction team broke ground on an ambitious project to transform Eero Saarinen’s iconic TWA Flight Center at John F. Kennedy International Airport in New York City into a premium hotel with 512 guest rooms and 50,000 square feet of meeting and event space. Despite the TWA Hotel’s location at one of the busiest airports in the United States, the developer and design team wanted to find a way to create a quiet guest room environment. 

“We really want to create a quiet space, where the guests are not disrupted.” says Jason Garone, vice president of construction at project developer MCR. “One of your biggest enemies in design can be acoustics. … If the building doesn’t have the right sound attenuation, people don’t want to be there.”

However, managing sound at the JFK Airport site proved quite complicated, Garone says. “The sound depends on which way the planes land and depart, on which way the wind is blowing. Some days it’s quiet. Other days you hear the boom of the engine,” he says.

Acoustic modeling and simulation

Achieving the acoustic goals at the TWA Hotel required a sophisticated acoustic modeling and simulation process, led by Cerami & Associates, the acoustic design consultant for the project. The process included several phases, beginning with establishing acoustic performance criteria for the guest rooms. “We began by developing the design objective for the  ‘acoustical experience’ within guest rooms,” says Christopher Peltier, principal at Cerami & Associates. 

The team then studied the acoustical impact of many aspects of the building. This stage of the process involved recording and measuring noise levels at various site locations, including on the rooftop. “We sampled sounds around the building. We went to the top of the south building and recorded local noise. We recorded the airplane jets, taking off and in taxiing. … We recorded the traffic outside—the taxis, cars that were honking,” says Garone.

“With all this data in hand, we were able to analyze the various design options in front of the owner,” says Victoria Cerami, CEO of Cerami & Associates.

Using the published acoustic performance data for several proposed glazing systems, the engineers and consultants from Cerami took the acoustic projections for the guest rooms and “made them tangible” through simulations, says Cerami. In the firm’s Acoustical Immersion booth, the owner and the TWA project team members were able to experience the modeled guest room sound experience for various façade systems’ options and compare them to the owner’s design objective. 

“[Cerami & Associates] has a sound booth and they could recreate the experience of being in the room with double-glazed units, with triple-glazed units, with triple laminated, with airgaps of different sizes,” Garone says. “That was a great tool, to go into their sound booth in their office and hear the systems’ performance. It allowed us to make an educated decision.”  

“Developing a cost benefit analysis based on the resultant calculations is the traditional approach at assessing the proposed systems. Our simulations add an additional component to the analysis, providing the qualitative component,” Cerami says.

The Cerami team also created acoustical models for several existing airport hotels, using actual acoustical measurements in guest rooms to provide comparisons for the owner and team. “The owner was able to understand how the current design or alternative designs ranked against other hotels in various locations. That helped them calibrate the performance to understand the relative differences,” Cerami says. 

The next step was to ensure the best acoustical results of the glazing system. The project team focused on developing the best-performing glass and glazing system for the project. “We did a lot of work with the makeup of the glass,” describes Peter Corsini, senior designer at Fabbrica. “One of the things that came out of testing was the order of the glass [lites] within the unit. The glass is triple-glazed with laminated layers. Which layer was where made a huge difference in how the glass performed [acoustically].”

Acoustic-performance systems

The chosen systems feature robust vision glass insulating units and framing profiles. “If you were to flip through the details, one item would jump out: the makeup for the vision glass. The glass is made up of seven layers of heat-strengthened glass and two airspaces. It is 45/16 inches thick. This is a significant piece of glass. I would estimate the average IGU [insulating glass unit] weighs 1,300 pounds,” says Corsini. “If you didn’t have the acoustic goals in mind, you could have gone with a more traditional 1¼-inch-thick unit using a more traditional frame.” 

Fabbrica manufactured and installed 2,055 unitized curtain wall units for the 78,000-square-foot façade. The typical unit measures 4 feet 4 inches by 9 feet 8 inches and weighs 1,700 pounds. The curtain wall framing is filled with 14-gauge steel, mass-loaded vinyl and fiberglass insulation to help eliminate outside noise within the hotel suites. 

Interpane fabricated the thick glass units, which are triple laminated and insulating, made up of six layers of low-iron glass plus one layer of Planibel gray glass, with  two argon-filled airspaces. The vision glass offers a sound transmission class rating of 48 and an outdoor-indoor transmission class rating of 41. 

Additional modeling

In addition to acoustic modeling, the TWA Hotel project team also relied on more traditional 3D modeling for the project, says Corsini. Fabbrica relied on 2D modeling with AutoCAD and 3D modeling with SolidWorks during both the shop drawing phase and the fabrication phase. “We used SolidWorks to model the actual curtain walls,” Corsini says. The team also relied on multiple mock-ups—visual, performance and acoustic. 

The TWA Hotel project is expected to be completed in early 2019. Beyer Blinder Belle is the restoration architect on the job, and Lubrano Ciavarra Architects is designing two new buildings associated with the project. 

Case Study 2-Laser Scanning at Shands Hospital

3D scanning and measuring technology reduces errors and speeds construction for complex façade and canopy


Right: Focus3D X 130 Laser Scanner. Photo courtesy of Faro Technologies

The University of Florida’s expansion of the Shands Cardiovascular Hospital, located in Gainesville, Florida, features an eye-catching canopy, with a glass façade backdrop. The 540,000-square-foot addition to the existing hospital is nine stories and provides 216 new inpatient beds. West Tampa Glass supplied the project with its 900 high span, 700 and 500 series curtain wall, as well as the insulating and laminated glass vision and spandrel glass for the exterior and canopy. 

Schedules for such a large and complex project like the Shands Hospital can become delayed due to extended lead times. “Typically, glaziers and fabricators need accurate, as-built dimensions to start a design or go by the design [of the building]. Which isn’t always built 100 percent correct to the design so scrap and lots of adjustments are needed out in the field which take up time and money,” says Brady O’Brien, sales engineer, Faro Technologies. To fast-track accurate measurement and avoid delays, project teams on the Shands Hospital used 3D laser scanning technology.

3D laser scanning

For the Shands Hospital, teams used Faro Technologies’ laser scanning technology which can capture as-built conditions of unfinished project exteriors by allowing operators to scan and create accurate, real-world models of the existing building. Faro’s equipment can scan a scene thousands of times per second, with the potential to capture over 900,000 points of information. Operators can then manipulate this scanned information in Faro’s Scene software. 

The project design by Flad Architects called for exterior cladding to align with the installed curtain wall mullions, which posed a challenge for N-RG Cladding, who contributed 100,000 square feet of aluminum composite material panels to the project, as well as terracotta and soffit panels, with phenolic panels for the canopy. The exterior design required N-RG’s panels to form a staggered, geometric pattern, while still aligning perfectly with the already-installed mullions. “It’s nearly impossible to make it all work based on what the architects drew,” says Yuri Melnichenko, CEO, N-RG Cladding. 

Prior to scanning technology, companies had to do just that: fabricate construction materials based on shop drawings alone. Since as-built conditions always deviate from original measurements, this meant costly re-fabrication and wasted time and materials, says Melnichenko. Glazing and cladding trades, which work on the exterior of the building envelope, are only allowed 1/16-inch deviation from the designer’s original plans, he says.

To meet these high standards, contractors can send an employee to physically measure the opening, but this is expensive and creates opportunities for human error, says Melnichenko. 3D scanning provides a more accurate, digital alternative he says. For this project, N-RG used the Faro x130 to scan the area, a process completed with only one operator. The scan captured about 90 percent of the building’s measurements, and created a 3D virtual model, downloaded to Faro’s Scene software, says Melnichenko. The data appears as individual points, or a ‘point cloud,’ he says, that maps the 3D environment.

Contractors then streamlined the raw data to focus on their specific construction area and “built” their own structure on top of the data using software like Kubit, a Faro product that allows 3D laser scan data to be imported into AutoCAD.  

Building for as-built conditions

Once N-RG had the as-built model for the Shands Hospital, contractors could draw and design panels to match the real measurements. “Otherwise it would be a guessing game, or we would be taking the chance on fabricating panels and them not fitting in the field,” says Melnichenko. Aligning staggered panels evenly with curtain wall mullions was imperative, as leaking can occur if the panel’s flashings are out of alignment or the elevations are incorrect. 

Roger Campla, vice president of West Tampa Glass, has also invested in 3D scanning technology, and used a Faro Focus 150 to scan the Shands project, along with Scene 5.0 software. Campla sees many benefits to this technology for the glazing community in verifying construction measurements and making it easy to get the right materials to fit both the existing structures. “3D Scanning along with CAD helps with geometrical verification and dimensioning, conceptual engineering and designing, and expedient accuracy and ordering,” he says.

Scanning the foundation

Faro’s O’Brien similarly emphasizes the scanner’s importance in allowing contractors to avoid costly adjustments in the field by recording the correct information to start with. Regarding curtain wall installation, this often starts with the positioning of the embed plates, he says. Embed plates are connecting structures that are bottom or top surfaces of the concrete slabs of a building, which the curtain wall itself is then welded to. While shop drawings outline this, they are a 2D medium, and the as-built conditions often require that measurements be tweaked, says O’Brien. “Laser scanning comes in for quality control to double check the measurements and verify that the embed plates are in the right place.”

West Tampa Glass supplied 1 5/16-inch insulated vision glass, insulated frit, and insulated spandrel, as well as 9/16-inch laminated vision glass for the exterior curtain wall. They also provided 9/16-inch laminated vision glass for the canopy. Guardian Glass manufactured the SN54 low-emissivity coated glass for both large missile impact and small missile impact. Tecnoglass was the glass fabricator. Skanska was the general contractor.