A Living Building
The Major General Emmett J. Bean Center in Indianapolis is among the largest federal complexes owned and managed by the U.S. General Services Administration (GSA) in the Midwest. The three-story structure totals approximately 1.6 million square feet, with 1.18 million square feet of usable office space. Originally built in 1953 to serve as the Army Finance Center at the former Fort Benjamin Harrison, the Bean Center today houses the Defense Finance and Accounting Service, the world’s largest finance and accounting operation, as its major tenant. Approximately 5,000 employees work in the building.
GSA selected the Bean Center in 2011 for a green proving ground pilot project involving the design and installation of an expansive photovoltaic rooftop array. A subsequent renovation phase, now underway, will also incorporate a number of site and building upgrades.
As the architectural and engineering firm selected to lead the design of the solar array installation and facility renovations, the team at Dewberry faced an immediate challenge. There was no current documentation of the entire building, just dozens of different sets of old and outdated drawings to sift through from previous building projects. With a building of this size, the lack of existing drawing documentation was the first issue to be addressed, and one of the most important.
Additional benefits of the laser scan process included the team’s ability to rely upon the BIM for a more efficient design of the building systems and architecture, identify and analyze existing equipment, and use the model for clash detection during design and construction. The scans would enable the team to generate an as-built construction model and allow for the potential of post-construction facility management with the model data.
After careful consideration, GSA decided to proceed with the scan technology. Despite the first-cost investment, the agency recognized the value of creating a 3D BIM that would streamline design, capture critical building data for potential future facilities management use, and support GSA’s goals for comprehensive energy modeling. GSA representatives also knew that this information would benefit future federal renovation projects that would use a scan-to-BIM approach.
The next step involved developing a plan and parameters for the laser scanning process. Decisions included determining the BIM level of development (LOD) and identifying what to scan and to what degree. The team ultimately decided to perform scans of the exterior envelope, critical areas of the site, interior spaces and above-ceiling areas to create a complete model.
Quantapoint, the consultant selected to perform the scans, divided the floor spaces into work packages to manage security and communications issues. ALTA benchmarks were used to set the buildings, with control loops on each floor (such as along hallways) and vertical control loops in stairwells between floors to increase accuracy. This control helped ensure that all of the equipment was calibrated and that images joined up accurately throughout the building.
Quantapoint used four crews simultaneously for exterior digitizing, which included the 500,000-square-foot roof area. The firm used an exterior loop of camera positions with interior tie-ins at major building exits. The grade loop was tied to the roof scanning with targets. The courtyards required a second grade loop, with tie-ins at the building exits and vehicle tunnels.
All of the exterior data was processed before the interior work began to allow for expedited use of the exterior models. The exterior data was processed into laser model form and delivered in Autodesk Revit Architecture.
The interior of the Bean Center consists primarily of standard office architecture with mechanical rooms on each floor. The building is a concrete slab structure with acoustic ceilings. Working above the ceiling grid represented the primary challenge, with more than 4,000 scan positions used above grid. Quantapoint developed an efficient method that allowed for the removal of only one tile per scan. Department of Defense requirements call for bracing mechanical/electrical equipment above ceilings, so the laser scan images would ultimately save considerable time in performing visual inspections in every room. All of the mechanical and electrical rooms were also digitized for future facilities management use.
With the as-built Revit geometric model in place, the modeling and design phases began. The BIM model enabled the Dewberry team to perform extensive solar studies on the roof, demonstrating the tracking of the sun and the location of shadows. This information allowed for an effective layout of the rooftop photovoltaics by using a comparison of the winter and summer solstice and avoiding shadows at different times of the year. The modeling was vital to the overall effort; in all, the rooftop solar panel installation includes 6,152 photovoltaic panels that generate nearly 2 megawatts of renewable energy--offsetting seven percent of the building’s electricity use.
The team also verified existing mechanical, electrical and plumbing systems and used the BIM to design the solar hot water heating system as well as to reconfigure existing systems to allow for required structural upgrades. To accommodate Department of Defense blast-resistance and bracing requirements, the scans supplied the model’s as-built perimeter data and helped to identify equipment for bracing.
For potential facilities management purposes, the BIM model includes extensive equipment data. The information meets Construction Operations Building Exchange (COBie) standards, which can include data for life cycle information such as timing for replacement and repair. Mechanical equipment, for example, is documented with such details as shape, clearance distances, installation history and manufacturer information, with a link to the manufacturer’s data sheet. This will allow for a dynamic tool in inventories and facilities management.
Due to the quick schedule, the team started with a model based on existing drawings of the building, which was created while the building was laser scanned, and adjusted the model to the scan information as it was received. Dewberry created a custom “Updated to Scan” parameter for the elements in the model, allowing for a graphical means to track updates as objects would turn green on the computer after they had been updated. Additionally, a filter was created that would highlight non-updated objects in red. Finally, the actual point cloud was overlaid in the BIM in critical areas to cross-check the accuracy of the model updates.
The use of the laser scanning technology for the Bean Center allowed for a fast start to the BIM management process. The approach has also helped to set workable onsite scanning procedures as well as standards for the development of BIM models for future GSA projects, including guidelines for scale and for tracking updates. Although the laser scanning process--one of the largest in GSA’s history--was certainly labor-intensive, the results were a valuable contribution to the modeling and renovation process for this important project.
BIM Levels of DevelopmentJennifer Taylor, director of virtual design for Dewberry, created Level of Development descriptions that are more specific than AIA E202 descriptions to better align with GSA goals. The information meets Construction Operations Building Exchange (COBie) standards and can incorporate life-cycle information such as replacement and repair schedules, which will enable GSA to use the model for facilities management.
- LOD 100 – 3D overall building massing and/or other geometric data
During the Conceptual Design Phase, the model consists of overall building massing and downstream users are authorized to perform whole building types of analysis including volume, orientation, cost per square foot, etc.
- LOD 200 – 3D object placeholder
During the Schematic Design and Design Development Phases, the model consists of generalized systems or assemblies with approximate quantities, size, shape, location and orientation. Users would include analysis of selected systems by application of generalized performance criteria. Elements are shown in 3D with maximum size purpose material and rating element ID.
- LOD 300 – 3D actual object
During the Construction Document and Shop Drawing Phases, analysis and simulation of detailed elements and systems by users is performed. Specific elements are confirmed as 3D objects with dimensions, capacities, and connections.
- LOD 400 – 3D actual objects with fabrication details
Objects modeled for fabrication and assembly are generated primarily by the trade contractor of fabricator. 3D elements are created and used for shop drawings, fabrication, and purchase of manufactured and installed items.
- LOD 500 – 3D as-built items
Post construction, model elements are per the as-built conditions and contain suitable information for the maintenance and operations of the facility.