Toledo-Lucas County library officials chose a building expansion design that is both contemporary and complementary to the original building.
TOLEDO, Ohio - Public libraries still offer a vast range of books and other print documents, but the emphasis is on accessible knowledge. This is certainly true at the main branch of the Toledo-Lucas County library system on Michigan Street in Toledo, Ohio.

This library offers a range of information services, from online learning to special programs for children, students, adults, seniors and those interested in areas such as genealogy, health or computer-assisted learning. Programs by authors and presentations by community leaders are regular events.

A recent addition to the library, along with a renovation of the original 3-story building, expands the capabilities of the facility and makes an important community center more user-focused. A comfort system featuring rooftop air-handlers and a high-efficiency, water-cooled screw chiller makes the building adaptable to widely changing building uses and comfort requirements.

The original 186,000-square-foot library building was constructed in 1939-1940. The building has a smooth limestone exterior with art deco facade and window ornamentation. Heating is supplied by natural gas-fired steam boilers, supplying both with low-pressure steam and hot water.

In 1986, the building was equipped with two Trane model CGWC 120-ton chillers with hermetic reciprocating compressors. These units supply chilled water at 45°F to air handlers located throughout.

In the mid-1990s, it became apparent that the main library was no longer large enough to meet the growing needs of its community. The decision was made to add an 85,000-square-foot addition. The Toledo architectural firm of Munger, Munger & Associates was named to design the addition.

The 3-story addition is different in appearance from the original building, standing on piers to create a covered parking area beneath the building. The exterior features long, curving walls with much of the wall space dedicated to windows. A fully glazed transition section connects the two buildings.

The interior of the addition has an open, gardenlike atmosphere and flexible public space that can be used for a wide range of activities. The garden atmosphere carries over the rooftop of the addition, which has grassy areas, planted berms, sidewalks, tables and chairs to accommodate library visitors.

Because of the size of the expansion, major comfort system improvements were required.

Additional cooling needed

The comfort system for the addition was able to use the existing boilers for heating, but required additional chiller capacity for cooling. The chiller unit selected is a Trane model RTHC water-cooled screw chiller, located in the basement.

This chiller uses R-134A for refrigerant. The project also involved adding a cooling tower to the existing tower on the roof of the original building.

The mechanical engineering work for the project was done by Korda/Nemeth Engineering, Inc. of Columbus, Ohio. The general contractor for the project was Mosser Construction of Fremont, Ohio, and the mechanical contractor was Hank's Plumbing & Heating of Toledo.

In order to maximize the amount of building space available for library functions, the decision was made to install the air handlers serving the building on the rooftop of the new section. The air handlers chosen to serve the new facility are two Trane Aire Systems units, one sized for 30,000 cfm and the other for 26,000 cfm.

The two air handlers have two-stage filtration, hot-water heating coils, chilled-water cooling coils and Dristeam gas-fired steam humidifiers. The units are equipped with supply and return fans, each with variable-frequency drives. Both units are equipped with Sonatrol silencers for air-distribution-sound control.

Distribution air from the new air handlers is modulated by the variable-frequency drives to maintain duct-static pressure. Air temperatures between 55°F and 65°F are delivered to the high-pressure distribution ducts. These supply 70 variable-air volume terminal boxes equipped with independent zone-control sensors.

Chilled water is typically supplied to the air handlers during the months of April through November, when the outside temperature is above 55°F. When outside air temperatures drop below 45°F, the system begins to control return air relative humidity at 30 percent. Hot-water perimeter heat is also supplied at most exterior window locations to help maintain even room temperatures.