New Building and Description of HVAC System
On May 6, 2003, the Georgia Archives opened its doors to the public in what is the organization’s fourth facility since its inception in 1918. The building is located in Morrow, Georgia about twelve miles south of Atlanta. Design of the building began in 2000 with the highest priority placed on building an archival facility that met current standards for providing a high level of security and environmental protection of the records. In addition to protecting the records, staff insisted the building be inviting and friendly to the public. A large reference room that looks out onto a landscaped garden, a two story glass atrium that can be used for events, exhibit space, classrooms, and tour windows into vaults and laboratory spaces were incorporated into the design.
The records storage vaults are a four story poured concrete structure, with the three-story office and work areas wrapping around the vaults in an L-shaped manner. Two of the four storage vaults are equipped with compact mobile shelving; the other two floors have tracks built into the flooring for future expansion. The first floor vault was designed to house maps and other oversize materials in flat files, as well as rare books and other non-standard items. The storage vaults encompass 60% of the building’s floor space, and if fully built out with compact shelving, the maximum storage capacity would be 257,000 cubic feet. Presently, there are about 85,000 cubic feet of records housed in the building, leaving space for many years of growth to come.
The building’s mechanical system is a complex multi-zoned constant air and variable volume HVAC system with eight air handlers, two chillers, and a desiccant dehumidification system to combat the high humidity prevalent in the Southeast. With the preservation of the collections as the top design priority, specifications required that the four vaults be able to provide conditions of 60 °F (+/- 5°) and a relative humidity of 35% (+/- 3%). The constant air volume (CAV) systems for the vaults are designed to take in 100% outside air and run at full fan speed 24-hours per day, 365 days per year. There are two 240 ton Trane Chillers designed to run at 38 °F in order to maintain constant low temperatures in the vaults. The system is, in fact, able to meet these strict design specifications even during Atlanta summers when outdoor air temperatures can average well over 90 °F, relative humidity levels consistently reach above 80%, and the dew point regularly reaches 70 °F.
Each of the four storage vaults has a dedicated air handling unit (AHU) serving the space that processes between 15,000 and 22,000 cubic feet of air per minute (cfm). These systems have chilled and hot water coils, desiccant wheels, a reactivation fan, and two gas burner drying units. Some dehumidification is achieved through re-heat; however, it is supplemented by two stand-alone desiccant dehumidifiers. They run on constant volume, and their design specifications are based on very humid conditions.
While the mechanical system provides environmental conditions for the collections that meet recommended standards for the long term preservation of archival collections, it is extremely difficult to economize the functioning of this system, resulting in substantial, and often unnecessary, energy consumption and excessive costs, both monetarily and environmentally.