NFPA Journal

     

Like many urban sites, the Museum of the Bible is on a constrained site, with train tracks to the south, roads to the north and west, and a neighboring building, the Washington Office Center, to the east. Back-to-back two-hour fire barriers between the museum and the office center provide the required party wall separation.

Fitting the entire museum, including the conference facilities and scholar-in-residence housing, into the historic cold storage building was not possible, despite the new construction above the historic structure and the infill addition of below-grade and vertical circulation space. The adjacent roads and railroad tracks prevented horizontal additions, leaving no space to expand the building footprint.

The adjacent Washington Office Center was under the same ownership as the historic structure, however, which provided a unique opportunity to expand the museum into—or, more accurately, onto—the adjacent office center. A new floor now provides space for lectures and housing for visiting researchers and is connected to the rest of the museum by a new elevator. Although the new floor serves the museum, it is part of the office center, both from a legal and a code perspective.

While the DC Building Code prohibits openings in a party wall between buildings on separate lots, it does permit designers to propose alternative approaches that provide an equivalent level of safety, much like Section 1.4 in NFPA 101®, Life Safety Code®. We were able to obtain such an equivalency to allow passage between the museum space and the new floor above the office center through the city’s pre-design review meeting (PDRM) process, which brings designers and reviewers together early in the project so that key issues can be resolved before the final permit review. These range from prescriptive provisions in the code that explicitly require AHJ approval, such as campus-style electrical feeds for fire pumps, to requests for equivalent approaches to prescriptive requirements, such as the openings in the party wall requested as part of this project. The reviewers involved could be limited to a single discipline or span the entire range, from fire protection to civil to zoning.

In our case, the discussion at the PDRM led to an approved equivalency that required additional fire-rated opening protectives at the elevator, a covenant agreement that would grant access to museum space in the Washington Office Center in perpetuity—even if it is sold to a future owner—and an additional elevator that firefighters could use to access the new floor directly from the office center’s lobby. This additional elevator is critical because fire department response to any alarm in the new conference or residential space would be to the office center’s lobby, rather than the primary elevator located on the museum side that staff and scholars use to access the added floor.

By participating in the PDRM process, we were able to work through the concept with the AHJ early in design, helping to reduce the risk that a fully developed concept would be denied during the permit review. The early feedback from the city also allowed the owner’s legal team to establish the necessary covenants prior to permit submission, rather than waiting for a review comment that would then hold up permit issuance. As a result, construction began on time and the museum was delivered on schedule.

Challenge: Atrium design and smoke control

To lend order to the complex array of spaces and functions inside the museum, we created a vertical hub-and-spoke circulation system within a large, central atrium that connected all the stories and encouraged occupants to use the monumental stair rather than wait for elevators. The primary circulation core is a calm, bright space that provides visitors both a place of respite and an opportunity to reorient themselves in the building. The core ultimately leads to the rooftop addition, which includes a restaurant, special event spaces, and a large performing arts theater.

With a vertical opening that is only slightly larger than the stair, we assumed that traditional hand calculations would be inadequate for designing the smoke control system. NFPA 92, Standard for Smoke Control Systems, contains several algebraic formulas for calculating the volume of smoke produced by a given design fire, but there are limitations to the applicability of those hand calculations.

Indeed, NFPA 92 (Section A.5.9 in the 2018 edition) explicitly indicates that empirical equations are not adequate for atriums with “varying cross-sections and complex geometry” and recommends alternative approaches such as computational fluid dynamics (CFD) models in those cases. Since the interaction between the smoke plume and adjacent balconies would not be captured by hand calculations or simple models such as zone models, we believed that a CFD model would be the most appropriate method for evaluating the smoke exhaust system design.

                    
The dramatic atrium stairway offered a focal point for the museum's interior but created a complex smoke control challenge for designers.

Our theory was confirmed when early computer-based smoke modeling results from our consultant, Jensen Hughes, using the fire dynamic simulator (FDS) developed by the US National Institute of Standards and Technology (NIST), indicated accumulation of smoke on levels four and five, even while the main smoke layer remained above the top of the stair. Analysis of those results suggested that the geometry of the space caused eddies of smoke on those levels, which drove the visibility below the minimum acceptable threshold of 30 feet.

In order to mitigate the eddies of smoke on those levels, overhead-coiling smoke curtains were designed to prevent smoke movement into the adjacent, occupied spaces. Upon activation of smoke detectors in the atrium, these curtains drop at a controlled rate to completely seal the openings into the atrium. When retracted, they blend into the ceiling and are nearly invisible.

The make-up air design also contributed to an effective, efficient smoke-control system. Since exhausting air from a space without replacing it will create negative pressures, make-up air must be provided to balance the exhaust air.

We have found that make-up air ductwork, grilles, and openings often have a more significant architectural impact than the exhaust fans and openings. While exhaust openings are generally located at the top of the space and can exhaust a significant volume of smoke through each opening, the make-up air inlets are usually larger and located on the lower levels. This often requires shafts, ductwork, and wall area for inlets that are in direct competition for space with other systems, building structure, and architectural features.

Larger inlets are often required to minimize the velocity of the make-up air, since high-velocity make-up air disrupts smoke plumes, causing them to mix with adjacent, fresh air. This mixing increases the volume of smoke that must be exhausted. They are generally located on the lower levels because injecting air directly into the smoke layer can increase the volume of smoke, negating the efforts of the smoke exhaust system.

At the Museum of the Bible, we provided make-up air from the adjacent spaces on Levels 1 through 6. This helped distribute the source of make-up air, so that no one floor lost too much space to make-up air openings. Although this included make-up air inlets on the upper levels, the CFD fire modeling results indicated that the smoke plume would not be disrupted by the make-up air flow and that the natural movement of air from the high-pressure area at the make-up air inlets toward the low-pressure area at the exhaust outlets would help keep smoke within the vertical opening.

Additional iterations of the fire model incorporating the final make-up air and smoke curtain designs confirmed the efficacy of these measures and demonstrated that the system would be expected to maintain tenable conditions for the design fires that were modeled. These results held true for scenarios that included fires in the center of the atrium opening, and for scenarios located next to the make-up air injection points.

Challenge: Coordinating 'museums within a museum'

Whereas traditional museums typically consist of exhibition galleries, spaces for lectures and educational activities, a shop, and perhaps a café, the Museum of the Bible was conceived and designed as a more ambitious and flexible institution, one intended to deliver a multidimensional visitor experience. This vision also created significant design and safety challenges for designers.

Long-term, permanent exhibitions occupy the majority of floor space within the original structure, and the project includes a variety of additional gallery spaces accommodating displays from visiting institutions, such as the Vatican Library and the Israeli Antiquities Authority. Each of these unique spaces had its own specialized exhibit design team, which in turn had its own methods of creating drawings, communicating to fabricators, and coordinating with the base building engineering teams. This approach effectively created a building of “museums within a museum,” as well as the need to standardize many of the building’s main systems—such as lighting controls, dimming panels, life safety devices, and communication pathways—without stifling the design of the spaces.

Due to the compressed schedule, necessary project phasing, and the large number of design professionals involved—more than 550 engineers, architects, and other construction experts—a traditional design-bid-build project approach would not have allowed the museum to be completed in the client’s desired timeframe. The general contractor, Clark Construction, was brought on to the project at the beginning, and constant collaboration between the design and construction teams helped maintain a tight schedule. Together with the general contractor, six exhibit design teams, and more than 60 specialty trade partners, the project team took an integrated approach early in the process, with specialty design-assist partners embedded with the design team—HVAC, plumbing, fire protection, electrical, and curtainwall fabricators, to name a few. This included weekly design coordination meetings with participation from all six exhibit design teams and the contractor, as well as quarterly project meetings where design progress was shared.

Because of the desired unique nature of each of the “museums,” the design teams needed to go beyond the standardization of the larger systems and find solutions for items that could not be standardized. These included features such as custom-colored, concealed sprinklers in a re-creation of Nazareth Village; the precise placement of fire protection devices in a vaulted, stretched fabric ceiling on the floor containing the History of the Bible; and the concealment of all infrastructure in a portion of the immersive walkthrough of the Old Testament on the floor containing Stories of the Bible.

Safety features had to be incorporated discreetly into a dense array of museum spaces and exhibits, including immersive exhibits like the re-creation of Nazareth Village, pictured above.

To understand why these elements were so important, presentations were held in each of the exhibit design team offices where the architects, engineers, and contractors all met to hear what items were most important to the exhibit teams and why. This often led to innovative solutions that could be incorporated into the base building design documents instead of creating a change order later in the project. Examples included the introduction of concealed fire alarm devices in areas where traditional devices would have interrupted immersive environments; routing of sprinkler pipes, conduit, and ductwork to ensure that certain exhibit areas would have un-obstructed ceiling spaces; and the development of custom metal baffles in the Vatican Museum exhibit that filled gaps in the fabric ceiling so that a second layer of sprinklers would not need to be installed above the finished ceiling.

During construction, this close communication continued with weekly meetings, and we worked closely with the fire alarm and fire suppression contractors to coordinate final locations for life safety devices and fire suppression equipment throughout all of the spaces. The solutions were not one-size-fits-all, and additional coordination was required to iron out installation details, sprinkler spacing, alternatives for traditional exit signs in immersive spaces, and integration with architectural and exhibit finishes. Separate workshops were scheduled for each of the “museum within a museum” spaces and were attended by the architect, the respective exhibit team, design engineers, the contractor, and all relevant subcontractors. The location of each grill, sprinkler, pipe, conduit, and sign was reviewed and documented, and where multiple trades needed to interface, details were hand drawn to work through the sequencing and final installation of devices. These details were incorporated into the subcontractors’ work and resulted in a shared responsibility for the final result. These meetings also helped keep lines of communication open, minimizing questions and miscommunications regarding intent.

We believe that The Museum of the Bible represents the future of cultural institutions, both in how it revolutionizes the visitor experience and in the measures it employs to ensure their safety. The museum serves as a model of what can be achieved through creative engineering, innovative construction planning, and superior collaboration. 

Sarah Ghorbanian, LEED AP, project manager; Viral Amin, P.E., LEED AP, principal, fire protection and life safety engineering; and Kyle Lehman, P.E., principal, fire protection and life safety engineering, are with SmithGroup, an architectural design firm in Washington, DC. Photographs courtesy of: SmithGroup