Events and Awards

Michaud Cooley Erickson project profile: Bell Museum of Natural History

Bell Museum of Natural History, St. Paul, MN
By Michaud Cooley Erickson August 13, 2019
The Bell Museum is a series of exhibit halls, which project out from the base, creating mass and volume. The fully glazed exhibit hall pictured here provides the grand entry and protection from the elements to students arriving by bus. The mechanical equipment is concealed in the screened yard pictured on the right side of the image.

Engineering firm: Michaud Cooley Erickson

2019 MEP Giants rank: 73

Project: Bell Museum of Natural History

Location: St. Paul, MN, U.S.

Building type: Educational facility, office building

Project type: New construction

Engineering services: Automation, controls; electrical, power; energy, sustainability; fire, life safety; HVAC, mechanical; lighting; plumbing, piping

Project timeline: December 2015 to January 2018

MEP/FP budget: $588,000

Challenges

As with any project, the Bell Museum had a list of unique challenges that the MCE team faced throughout the project. Specifically, selecting the mechanical heating, ventilation and air conditioning (HVAC) system takes careful consideration. Chilled Beams, Variable Refrigerant Flow (VRF), Geothermal and Dedicated Outdoor Air Systems (DOAS) systems were modeled and compared to a more conventional Variable Air Volume (VAV) system with low temperature baseboard radiation heating. One of the challenges for the mechanical system was to provide comfortable conditioning and ventilation with 10 staff people in the building during nonbusiness hours, up to 350 people during large events and everything in between.

The cylinder structure in the middle of the museum houses the state of the art planetarium, which seats 120. The mirrored finished circular cut-out provides visual interest and reflection to guests as they pass along the central staircase, entering the exhibit space.

Solutions

The final mechanical system selection includes two large interconnected air handling units. Each air handling unit includes two direct drive fans with Variable Frequency Drives (VFD’s). To provide the ability to reduce the airflow down to 25% of maximum through fan shutdown and even lower using the VFD’s, resulting in significant energy savings.

The iconic dioramas created by Francis Lee Jaques in the 1950s were moved from the previous Bell Museum on the Minneapolis campus with detail and care. The lighting and humidity controls are extremely important to preserve the natural history for many more generations.

Ventilation air to the building is provided through a DOAS system, which includes an energy recovery wheel. During low cooling load conditions, the entire building can be conditioned with this air handling unit alone. When space cooling loads exceed the capacity of the DOAS system, the air handling units are ramped up to meet the demand. The DOAS system and conditioning air units share common distribution ductwork downstream of the zone control VAV boxes.

The museum was designed to connect the visitors to the greater context while being mindful of the natural world around the building. In this photo one can see how visitors are learning about the agricultural research programs at the University of Minnesota. Also noteworthy, the windows have a bird-safe application to prevent bird-strikes.

Chilled water for the air handling units is provided through air cooled chillers, which include heat recovery. The heat recovery provides dehumidification control through the DOAS unit in the summer when the exhibit design conditions are 74°F and 50% RH maximum. The separate cooling loop uses chilled water in the summer and a heat rejection coil in the DOAS unit during the offseason, which uses the outdoor air to cool the loop, which the added benefit of using the rejected heat to preheat the DOAS outdoor air.

The heating system for the building is condensing boilers operating between 140°F and 110°F. This provides a boiler operating efficiency of about 92%. The heating water serves fin tube radiation, radiant panels and heating coils installed in parallel fan powered VAV boxes. Because the ventilation air to the spaces is provided through the DOAS, the primary air through the parallel fan powered VAV boxes can be shut off before the heating coil is activated, resulting in zero reheat.

With more than 110,000 annual visitors, the Bell Museum is home to permanent and rotating exhibits. The woolly mammoth has been a highlight for visitors of all ages, transporting each of them to a different time in the Earth’s history.

The main challenge of the power aspect was determining generator power requirements for critical equipment for the exhibits, including getting the correct amount of power to all the lighting components of the Bell Museum. Lighting obstacles came with controlling sound carried by heat sinks in the planetarium and concealing light fixtures, so the focus remains on the exhibit. Proper lighting design was key on the interior to bring the exhibits to life, but also on the exterior and throughout the site to showcase the building.


Michaud Cooley Erickson