Central Plant of the Field Museum of Natural History, Chicago

The original central plant of the Field Museum of Natural History was constructed in the mid-1930s and the system had exceeded its life expectancy. The down time and repair costs were increasing, and there was no capacity for future growth.

The plant needs to run well because demands placed on it are substantial. The Field has more than 1 million sq. ft. of space to manage and preserves about 22 million artifacts ¾ reportedly the fourth largest of its kind in the world - for scientists, researchers and staff. The museum also attracts more than 1.8 million visitors each year and hosts hundreds of special events annually.

Looking Long Term

A key issue was the landmark status of the Field. The historic envelope of the facility had to remain intact.

Operating heating and cooling systems 24 hours a day, 365 days a year was also a factor in the planning, along with limited staff and budget.

The project team decided a long-term focus was necessary. A build-to-last philosophy that emphasized flexibility, redundancy and simplicity, with equipment that would be easily maintained and repaired, was embraced.

The design for the HVAC systems also included the projected five-year growth of the collections space.

Has Multiple Components

The new central plant consists of the total replacement of the major heating and cooling systems, including the replacement of boilers, chillers, fire pumps and air-handling units.

In addition, a thermal ice storage system was designed as part of the cooling system. Energy-saving initiatives were implemented, such as making ice for the HVAC system at night when the cost for power is cheaper than it is during the day. This will reduce the overall operating costs of the museum's yearly electric consumption by about 25 percent.

The new central plant was constructed while the Field was in operation, and it was built underground southwest of the museum entrance to avoid detracting from the historic envelope of the building.

A deep excavation with sheet-piling retention was built to deal with the water table and to keep the excavated hole's walls from collapsing.

The central plant was designed to provide heating and air conditioning to all building spaces, including a planned growth of an additional 500,000 sq. ft. When completed, the building's main and remote mechanical system will be monitored and controlled from a fully computerized and central control room that uses an automation system.

Thermal energy storage was selected to reduce operating costs. The low-pressure boilers, electric chillers and automation system maximize efficiency.

Project Results

The thermal ice storage system, which consists of 48 ice-storage tanks, circulates chiller water throughout the building. The thermal storage uses 200,000 gallons of water, making ice at night. During the day, as the ice mixture melts, it is fed to the air-handling units distributed throughout the building.

The three new low-pressure steam boilers run on natural gas and function at 400 horsepower each and provide the steam for space heating.

A system integrates energy supplies and users, providing a mechanism to monitor and manage the museum's energy resources effectively. A software platform is used to make information readily available to users. This control system ensures that temperature and humidity requirements for the areas of the museum are continuously met.

The jury said, "The logistics on this project were very difficult. To fit new equipment on this small campus and to do it in such a way that allows the museum to growth was very challenging."

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