General Contractor: Shapiro & Duncan, Inc. Architect/Engineer: KTA Group Contract Amount: $2,738,131 Start Date: November 28, 2011 Completion Date: April 15, 2012 (substantial completion)
Challenge
Shapiro & Duncan, Inc. had to replace the entire chilled water plant and motor control center in the penthouse of a 12-story, fully occupied class A office building located in the heart of the downtown D.C. business district (on the corner of 14th and I Streets N.W.). Our toughest challenge was keeping this fully-occupied building operational 24/7 and avoiding any tenant disruptions during construction.
Our scope of work included replacement of two 600-ton water cooled chillers, one 150-ton water cooled chiller, two 2-cell cooling towers, additional structural steel, new hydronic piping, one waterside economizer heat exchanger and eight base-mounted pumps with associated accessories (including new 4″ high concrete housekeeping pads). Also included in the scope of work were:
A new chemical water treatment system and heat tracing;
Air separator;
Expansion tank;
New motor control center;
New electrical distribution;
Two refrigeration exhaust fans and duct work;
Nine new replacement air handlers (each with an electric duct heater);
Two fan coil units;
One split system heat pump and condenser;
Thermal insulation;
Air and water balancing;
Installation of a new central plant control system integrated w/ theexisting building management system (BMS); and
Construction of an elevator machine room.
Solution
Construction was performed during the winter months when the ambient air temperature allowed for reduced building cooling demand. Phasing plans were closely coordinated with the building engineer and building management so that the chilled water systems remained operational.
The 600-ton and 150-ton water cooled chillers, associated pumps and cooling tower were test run on site so that they could be installed and operational before the existing chiller, pumps and cooling tower were taken off line and removed.
Shapiro & Duncan’s state-of-the-art building information modeling (BIM) system was used both for exterior construction for the cooling towers and for interior work in the mechanical room. Using programs created by our BIM team, Shapiro & Duncan’s 51,000-square-foot fabrication shop in Landover, MD was able to prefabricate many of the pipe sections and valve assemblies. Our BIM team would come out to the site and take measurements, go back to the office and build the model. The BIM model would be sent to our field superintendent for review and approval prior to sending it to the fabrication shop. Once these components were fabricated, they were put on a truck for delivery to the site. At the job site, a crane was used to lift everything up to roof.
All equipment load transfers and equipment lifting were scheduled over weekends; closing lanes on both 14th Street and I Street for crane placement and staging.
Result
The building remained on-line and with sufficient cooling capacity to meet the off season demand loads throughout the renovation. In the final analysis, the keys to success were up-front planning and effective coordination between our BIM team and field superintendent with our vendors and subcontractors which made everything happen smoothly. On March 22, 2013 this project received a Craftsmanship Award from the Washington Building Congress as a testimony to the quality of the work performed on site.
Feedback from the building owner has been strongly positive. According to Mark Keller, Chairman and CEO of Edge Funds Advisors, “The job required perfection in order to execute at a number of high levels including organization, on-going building operations and integration. Shapiro & Duncan executed the complex and large scale retrofit on time and in budget. They significantly reduced the risk associated with on-going building operations and its tenancy.” In fact, one representative of the owner said, “We could barely tell you guys were in our building working.” In addition, we were told by another member of the building owner’s staff that energy costs started going down immediately after the new system was operational.
