Inside Mansueto, there are no books in sight. On the surface, that is.

Defying architectural and engineering convention, the University of Chicago (U of C) did the unthinkable: they put 3.5 million volumes, including some of the world’s rarest manuscripts, 45 feet below the Chicago water table and put a greenhouse on top.

Opening in the spring of 2011, the 45,000-sq-ft Joe and Rika Mansueto Library set out to achieve three goals: the underground storage of millions of rare manuscripts, a glass reading environment with access to the manuscripts, and a back-of-the-house conservatory for restoration.

With multiple spaces that each have their own unique HVAC loads, humidity control needs, and conservation requirements, Environmental Systems Design (Chicago) took a tiered approach to mechanical design, providing the Grand Reading Room, the archival storage area, and the preservation laboratories with equally unique mechanical systems.

GRAND READING ROOM

The project’s greatest challenge proved to be creating a reading environment beneath the library’s glass dome that would meet both local and national energy codes, thermal requirements, and the school’s daylighting and operational efficiency goals.

Using computational fluid dynamics (CFD) modeling to determine the right solution for the space, ESD imputed space and occupancy requirements, which include a constant temperature of 75°F with 50% rh (55.1° dewpoint) in summer and 30% rh  (41.5° dewpoint) in the winter in the three-story-tall, 8,000-sq-ft open plan Grand Reading Room.

The result was a two-pronged approach to cooling: a perimeter system was designed to directly address the external heat loads from the glass, while an interior system was created to provide local comfort cooling. Maintaining a perfect balance between the two is critical to occupant comfort, since frigid Chicago temperatures create a great conductive loss for the space during the winter and the city’s hot sun results in heat gain during the summer months.

The goal of the perimeter HVAC system is to eliminate unwanted solar heat gain and effectively address the external load. Here’s how it works: round floor diffusers (Figure 1) at the perimeter of the room shoot air up 12 ft along the interior side of the dome to address the heat load at its source. This air will slowly drop down into the occupied zone (6 ft and below), providing additional comfort cooling benefits to the space. Above 12 ft, the unconditioned, unoccupied zone may reach as high as 120°. Not conditioning the unoccupied space above reduces operational costs and minimizes mechanical loads.

The second arm of the cooling system is dedicated to the Reading Room’s comfort cooling. Fourteen kiosk diffusers spread throughout the space provide local lighting and air distribution and serve as informational kiosks to the U of C student body. The kiosks provide a sustainable approach to local cooling by conditioning the immediate air around them. Working together, they are able to maintain a uniform temperature in the space. The kiosks rise over 10-ft-tall and further the desired architectural look, serving no structural purpose in the space.

A single-zone VAV AHU (AHU-8), arrayed-fan wall design with VFDs, chilled water coils served from the central chilled water plant, particulate filters, and demand control ventilation for enhanced IAQ all work together to provide the Reading Room cooling systems with the air supply they need.

ARCHIVAL AREA

The 17,000-sq-ft sub-surface archival area has distinct temperature and humidity criteria required for the preservation of some of the world’s rarest books. Working with conservation specialists, ESD determined lower level archival storage room performance targets of: 60°constant temperature, plus or minus 2°and 30% rh, plus or minus 5%.

Four 15,000 cfm constant volume air handlers with particulate filtration were specified to achieve an effective temperature distribution within the 50-ft. high space (Figure 2). The constant volume AHU (AHU-5) specified provides desiccant dehumidification with high-pressure plant steam for regeneration, HEPA particulate filters, and two stages of gaseous carbon filtration to minimize biological, mechanical, and chemical damage to any materials. The control sequence relies on primary and redundant vault temperature and dewpoint sensors in the space. The humidification is provided by a clean steam generator and reverse osmosis water purification systems.

Located 50-ft below the surface in a small doughnut at the center of the archival area are eight air-handlers. Four serve their neighboring archival space, and the other four serve the Grand Reading Room’s perimeter cooling system. Another underground space, located between Mansueto and Regenstein Libraries, hosts five more air handlers. One serves the archival area and the other four service the Grand Reading Room’s interior kiosk system and the preservation and conservation spaces on the ground floor.

PRESERVATION AND CONSERVATION

Assuming 6,000-sq-ft of the ground level, the library’s Preservation Department is made up of the conservation and digitalization laboratories. The conservation lab includes special paper washing sinks, fume hoods for chemical treatments, bookbinding equipment, and flexible workstations that help conservationists preserve original artifacts. In the digital technology lab, large-format digital cameras create high-resolution digital images of unique book and paper materials that are too fragile for traditional conservation treatments or frequent handling. To-gether, the labs allow the library to conserve collections for future generations, while providing worldwide access to digitized collections online. Both laboratories serve all campus libraries, handling materials in both the general and special collections.

The ground floor preservation labs have a performance target of 75° and 45% rh (52.2° dewpoint) year-round. The constant volume air handler selected (AHU-11) provides dehumidi-fication from the central chilled water plant, HEPA particulate filters, and two stages of gaseous carbon filtration to address biological, mechanical, and chemical damage. The area is also served by two lab fume exhaust hoods with bag in, bag out HEPA filtration. Each lab has a dedicated reheat coil and clean steam humidifier for individual zone control.

An engineering and architectural first, the University of Chicago’s Joe and Rika Mansueto Library will lead its class in innovation, efficiency, and conservation, raising the bar for tomorrow’s university libraries. A formal dedication ceremony for the library was scheduled for November 2011. ES