Georgia Gwinnett College’s Building-A, located in Lawrenceville, Georgia was originally built in 2001, comprises approximately 124,000 GSF, and currently has 117 roof-top HVAC units. In 22 years of continuous operation, fewer than 20% of these original commercial grade rooftop units have been replaced, and the remaining units are well past their expected life cycle. The primary scope of the project is to replace the majority of the existing rooftop HVAC units and transition to a centralized zoned hydronic system. The project includes five (5) base-scope 25,000 CFM air handling units (AHUs) serving VAV terminal units with hot water reheat coils as follows: • AHU-1 is a 100% outside air (OA) lab unit with hydronic heating and cooling coils and a fan array. A general exhaust fan with VAV general exhaust terminals will be provided for the labs. • AHUs-2 through 5 (with add alternate AHU-6) are 25,000 CFM energy recovery units with hydronic cooling and heating coils, total energy recovery wheels, and supply and exhaust fan arrays. Hot water will be provided by two (2) new N+1 boilers housed in a new boiler room and secondary pimps. Chilled water will come from two (2) new 250-ton air-cooled chillers with 3 N+1 primary chilled water pumps. The boiler room and three (3) new MERs will be created by repurposing existing office and classroom space within the building. A new mechanical yard will also be constructed within the existing parking lot to support the new system infrastructure. Approximately 10 of the existing rooftop units will remain in service and receive new control systems to integrate with the updated building systems if the AHU-6 alternate is not taken.
