800 North Glebe is a 10-story 316,000 square-foot trophy mixed-use office building.  Retail and public gathering spaces are located at street level in the 2-story lobby of the building.  The remaining nine levels will provide class-A mixed-use offices.  800 North Glebe was designed for LEED Gold Certification by utilizing numerous strategies to minimize its carbon footprint. 

The 10-story façade, created by three sail-like sweeping glass curtain walls, accentuate the sight lines of the building.  Radial lines and circles were widely used to define the crown and drum feature of level one and the sail feature of the remaining levels.  Building setbacks are located at level four, six and eight to give dimension to the building.  Refer to figure 1 for visual representation of façade features.

Retail and community spaces on the ground level offer 14’-6” ceiling heights with floor-to-ceiling glazing.  Over the main building entrance, there is a diamond expression decorative composite metal canopy with a plaster soffit and sunguard ultrawhite laminated backlit glass. See figure 2 for visual representation.  Offices on levels two through eight have 9’-0” ceiling heights, with the remaining two levels will have 10’-0” ceiling heights.  A 3-level parking garage is shared between 800 and 900 North Glebe which offers ample parking at a ratio of 1/580 RSF. 

Innovative sustainable and responsible design practices are one of the designer’s primary goals.  Integration of sustainability and every day design by minimizing the carbon footprint, balancing energy and resources and feasibility all went into the design on 800 North Glebe.  In accordance with the U.S. Green Building Council’s Leadership in Energy and Environmental Design, the owner has a goal to achieve LEED Gold Certification, which the designers fulfilled.  LEED Gold Certification requires the design to attain at least 34 out of 61 possible points. 
           
A breakdown of anticipated points:
Sustainable site: 10/15 of attempted
Water efficiency:  3/5 of attempted
Energy and atmosphere:  5/14 of attempted
Materials and resources:  3/11 of attempted
Indoor environmental quality:  9/11 of attempted
Design process and innovation:  4/11 of attempted

Substructure:
           
Geotechnical studies performed by ATC Associated Inc. reported site and subsurface conditions encountered details their geotechnical recommendations for the project.  Three levels of parking make up the substructure of 800 N. Glebe at roughly thirty feet below existing grade.  Analysis indicated that spread footing foundations would be the most feasible for a majority of the structure.  However, under interior wall and column footings the foundation be designed with minimum widths of 18” to 24”.  Under the ground level lobby area, caissons needed to be a minimum diameter of 60” and a mat foundation would be sufficient when designed for a maximum allowable bearing pressure of 3.5 ksf. 
3 ksi normal-weight concrete (NWC) is used for the foundations and interior slab on grade, the garage SOG uses 4.5 ksi NWC and the cellar columns are composed of 4 ksi and 8 ksi.  Reinforcing varies in size throughout the footings and caissons, depending on thickness.


Superstructure:

One-way slab for the ground level retail include 10” thick slabs with 10’-0”x10’-0”x5.5” drop panels.  Plaza slabs are 12” thick with 10’-0”x10’-0”x12” drop panels. Concrete strengths for the ground level include 3 ksi (SOG), 5 ksi (plaza slabs and framed interior slabs) and 4,6 & 8 ksi (superstructure columns).  Post-tension design allowed for greater bay sizes of 30’x46’.  Greater bay sizes offer more efficient floor plates (30,000 SF) for the tenant.  Girders range in size from 48” wide x 18” thick to 72” wide x 20” thick.  For levels two through six, two-way mildly reinforced slabs and one-way slabs over post-tension girders are implemented.  Above level six, the superstructure consists of only one-way slabs over post-tension girders. Two-way slabs are 10.5” thick and generally reinforced with #5 @ 10” in both directions.  Drop panels in these areas are typically 10’-0”x10’-0”x7.5” to alleviate punching shear at the columns.  Slabs over the 36” diameter column are 12” thick with #5 @ 12” parallel to the girder and #6 @10” perpendicular to the girders, due to the cantilever action. 

Lateral System:

Shear walls in the core of the building provide the entire lateral support.  Two 12 in thick “C” shaped walls, 31.83’ long East/West and 9.58’ North/South per each “C”, encasing the elevator banks, reinforced with #4 horizontally and #5 vertically.  From the sixth floor down, walls running North/South are specially reinforced three feet from each end with #7 and #8 rebar.  Great care was given to limit the size and number of shear walls so as not to modify the floor layouts. 

The electrical system used to power 800 North Glebe is controlled by 480/277/V 3-phase 4-wire system carried by a 3000A busway.  The utility service room is located in the Northwest corner of the first and second parking levels of the garage.  An emergency generator can provide 450 KW of power to emergency lights, fire pump, sump pumps and stairwell pressurization fans through a 480/277V 3 phase system.

There are a variety of lighting fixtures used on the site.  The electrical consultant recommended using fixtures that utilized MR16 types lamps, with remote transformers where required.  All exterior fixtures are wet rated.  Interior fixtures included are surface mounted F32T8s, wall mounted CFLs and recessed F28T5s.  Occupancy sensors are to be installed on all office levels, but may be manually overridden by wall switches.