AT&T, Multiple Sites

Various Facilities

Small building with tall communications tower behind it.


GBA provided direct digital control (DDC) system commissioning services for six projects totaling 3,700 control points and 579,000 square feet. In addition to acting as commissioning agent, GBA was the mechanical, electrical, and controls design engineer on all six projects, which included 155,000 square feet of building additions with 29 new air handlers, 18 new chillers, and eight new diesel generators.

DDC System Commissioning and Design

GBA prepared design documents for mechanical and electrical systems. Project scope also included the preparation of commissioning specs, including prefunctional checklists, control system functional performance testing (including trend logs), contractor requirements for Operation and Maintenance manual development, review of the control system contractor’s as-built documents, and owner training. GBA reviewed shop drawings for hardware and software; sequences of operation, including power failure, DDC system failure, and fail-safe/backup modes of operation; wiring diagrams; panel configurations; communication bus riser diagrams; field interface equipment; DDC system redundancy configuration; central operator workstation hardware and software including graphic user interface screens (floor plans, system flow diagrams); control loop control/alarm setpoints; and portable operator interface equipment. GBA also reviewed and approved completed prefunctional checklists and trend logs before functional performance testing.

GBA completed functional performance testing of every input/output point, encompassing all the newly provided equipment and additional chiller plants, air handlers, and terminal devices (air and water) associated with the existing building space. Work included coordinating the controls contractor’s training for the owner’s operations staff. Training included three phases:

  1. Classroom training
  2. On-site training with installed systems
  3. Follow-up training approximately one month after functional performance testing was completed

View More Projects

Interested in learning more about how GBA can assist with your facility objectives? Our portfolio is a great place to start. 

Skyscraper board room

430 N. Michigan (Realtor Building)

A large-scale vertical expansion called on GBA's analytical, design, and commissioning skills.

Hallway with rehab equipment

Shirley Ryan AbilityLab, Pediatric & DayRehab Center

This outpatient center serves children and adults; GBA provided engineering design services for the adaptive reuse project.

Exterior of Todd Building, University of Kentucky

University of Kentucky, Lee T. Todd, Jr. Building

An ASHRAE Level 1 audit,  retro-commissioning, and a lab ventilation assessment improved sustainability.