BUILDING NAME: OFFICE BUILDING LOCATION: NORTHEAST UNITED STATES PRIMARY OCCUPANT: CONFIDENTIAL FUNCTION: HEADQUARTERS BUILDING SIZE OF BUILDING #1: 390,000 S.F. STORIES: 1 PARTIALLY BELOW GRADE; 3 ABOVE GRADE CONSTRUCTION DATES: NOVEMBER 2010 - MAY 2013 CONTRACT AMOUNT: APPROXIMATELY $535 MILLION DELIVERY METHOD: DESIGN-BUILD
PROJECT TEAM INFORMATION
OWNER: CONFIDENTIAL GENERAL CONTRACTOR: CLARK CONSTRUCTION GROUP - WEBSITE DESIGN ARCHITECT: PERKINS + WILL - WEBSITE INTERIOR/LANDSCAPE ARCHITECT: HOK - WEBSITE ARCHITECT OF RECORD: WDG ARCHITECTURE - WEBSITE MEP ENGINEER: GIRARD ENGINEERING - WEBSITE STRUCTURAL ENGINEER: CAGLEY & ASSOCIATES - WEBSITE CIVIL ENGINEER: LOIEDERMAN SOLTESZ ASSOCIATES - WEBSITE
ARCHITECTURE DESIGN COMPONENTS
Building One (Figure 1) of the headquarters building is designed to provide a comfortable office space that features extraordinary views of the landscape elements and city skyline that lays beyond the building’s façade. The building consists of a north-south oriented main structure with three “fingers” that extend to the west. A small “thumb” extends to the north and features a childcare center that will provide services to employees with young children. Due to the subterranean nature of the structure, the floors are labeled in reverse, with Lower Level 9 being the lower most floor, and Lower Level 5 being the top floor of Building One. The tiered structure is nestled into a large hillside, with one story partially below grade that connects to buildings Two and Three, and three tiered levels above grade that overlook a large pond to the west. A large courtyard is located to the east of the structure, and is visible from Lower Levels 8-5.
Figure 1: Building One
ARCHITECTURE HISTORICAL REQUIREMENTS
All designs and exterior material specifications were reviewed by a historical consultant to ensure compatibility with adjacent Civil-War era buildings that will eventually be remodeled for adaptive re-use. The brick façade was specially designed and specified to mimic the adjacent buildings (Figure 2).
All historical relic findings were reported to a historical consultant who determined whether archeological exploration was warranted, or if construction could proceed as planned.
HISTORICAL STANDARDS National Historic Preservation Act ADM 1022.2 GSA Procedures for Historic Properties
Figure 2: Adjacent Historical Building
MODEL CODES OSHA General Industry Safety and Health Standards OSHA Construction Industry Standards GSA Facilities Standards for Public Buildings Service (P-100) NFPA 70 - National Electric Code 2005 Edition - Amended by DCMR 12C Supplement (2008)
ZONING Not applicable for Government owned sites.
ARCHITECTURE BUILDING ENCLOSURE
The headquarters building consists of cast-in-place concrete decks with exterior under-slab concrete beams and CMU/masonry knee walls with a curtain wall facade in between (Figure 3). The following is a description of the built-up system.
BLOCK WALL The concrete masonry units used on the headquarters building are 10 inches thick, and are reinforced with rebar that is attached to the concrete slab with HILTI bolts and are fully grouted in every cell.
WATERPROOFING Multiple waterproofing systems are used on the headquarters building. They are as follows:
Damp-proofing Continuous cold applied, emulsified-asphalt damp proofing is applied in two coats to the exterior face of concrete and masonry backup walls for exterior stone masonry retaining walls. Damp proofing must lap flashing, masonry reinforcement, veneer ties, structural members, concrete slabs and other penetrations by a minimum of ¼ inch.
Sheet Waterproofing Vertical exposed, backfilled, and landscaping walls are waterproofed using bituminous sheet waterproofing, affixed to surfaces using cold applied, emulsified-asphalt waterproofing. Vertical installations utilize Preprufe 160R waterproofing membrane by W.R. Grace & Company.
General Notes All waterproofing shall be VOC compliant. Filleted corners are given two coats of liquid membrane. All patching and terminations are completed with gun or trowel applied mastic waterproofing.
FACADE The exterior masonry walls are sheathed with an air barrier, R13 solid foam insulation, air space and nominal clay bricks that are tied to the structure through the use of traditional brick ties and reinforcement.
Curtain Wall In some areas, blast-rated windows are sandwiched between the under-slab concrete beams and the CMU knee walls and are surrounded by nominal clay brick. These windows are attached to the under-slab and CMU walls by steel embeds.
In other areas, the entire façade is comprised of curtain walls. The system is attached to embeds in the concrete slab by steel bolts. The window tops are affixed to blast absorbent brackets that are bolted to the under-slab beams. The windows themselves feature dual pane, heat treated glass, are double-sealed by polyisobutylene and silicone, and are broken up by aluminum mullions. In office areas, the exterior glazing is simply tinted. In mechanical spaces, where there are not air intake louvers, the glass is frosted and opaque to hide the equipment within but maintain the architectural aesthetics of the building. Solar shades are staggered across the entire curtain wall. Some shades are three stories in height, while others only extend one floor in height.
ROOFING Hot fluid applied rubber based waterproofing will be used on all exterior horizontal concrete surfaces. The waterproofing consists of a minimum of 0.41 mm of high density polyethylene film, 0.61 mm of membrane synthetic adhesive and 0.076 mm of a protective coating.
Built up green roofs will receive reinforced thermoplastic rubberized asphalt membrane applied to provide a minimum base coating of 2.29 mm, with a fabric reinforcement layer topped with 3.175 mm of top coating, complete with all flashings and terminations. The fabric reinforced Monolithic Membrane 6125 by American Hydrotech Incorporated was used for these applications.
SUSTAINABILITY PASSIVE FEATURES
Although the headquarters building design does not feature any active sustainable features, extensive passive features assist in the achievement of LEED Gold. The entire project will feature approximately 400,000 S.F. of green roof as well as four large interior courtyards, the largest of which will house numerous bioswales. Building One will serve as the western border for the largest interior courtyard, as well as contribute roughly 125,000 S.F. of green roof area. A large retaining pond, located to the west of Building One, will collect all excess rainwater that is not absorbed by the green roofs and is collected by the bioswales within the main courtyard. Sunshades, which are responsible for enhancing the aesthetic appeal as well as reducing solar gain through the extensive exterior glazing, are present on all curtain wall facades.
In addition to these sustainable exterior features, the headquarters building features sustainable wood finishes, low VOC adhesives and paints, 100% recycled insulation, and high-efficiency HVAC systems with medium and low pressure ductwork that feed a plethora of localized variable air volume boxes that will further contribute to the LEED Gold rating.