Electrical | HVAC | Plumbing Engineering

The DDSO occupies a one-story, 60,000 SF office building with partial basement/crawlspace. The building was constructed in 1948 and is equipped with steam absorption chiller that supplies chilled water to seven air handling unit (AHU) cooling coils serving the building. The chiller system, installed in 1972, was unreliable, maintenance intensive and had reached the end of its useful life. Watts was hired to provide design and construction administration services to replace the existing absorption chiller/cooling tower and distribution systems. The project was designated a fast track project with an approx. Eight month schedule from start of design to equipment start-up. Watts conducted field investigations of existing air handling systems, chilled water distribution, electrical and controls systems to document existing conditions. Building cooling loads were calculated using Trane Trace® computer modeling software, and several chiller options were evaluated, including variable speed centrifugal chiller with cooling tower and air cooled chillers. The Owner’s requirements for low maintenance and simplicity of operation, coupled with project schedule, supported the use of a packaged variable speed, air cooled chiller/pumping system to simplify installation and maintenance, reduce energy use, reduce field labor, and accelerate schedule to meet spring start-up date. Schematic and final construction documents, specifications and estimate were prepared to replace the existing systems. The fast track schedule required that Watts coordinate with a preferred vendor to select chiller/pumping system and to generate approved submittal of packaged chiller for expedited purchase/delivery. The design included new electrical room, transformers, backup gas-fired generator, fire alarm modifications, and water treatment system plumbing. Existing pneumatic controls at AHUs were replaced with programmable electronic controls capable of interfacing with future Building Management System.