Construction recently began on the modernization of the Smithsonian Institution’s National Air and Space Museum, one of the largest and most visited museums in the world. Set along the National Mall in Washington, D.C., the museum will remain open throughout the seven-year, multi-phase renovation. The construction start has followed six years of careful planning, including extensive three-dimensional modeling that informed the building design process.

The massive, 687,000-square-foot facility opened in 1976 during the U.S. Bicentennial. The renovation was led by Quinn Evans Architects with Mueller Associates providing mechanical, electrical, and plumbing engineering, will completely replace the museum’s aging building systems among other transformative upgrades. 

Mueller Associates is a MEP firm that specializes in cultural, educational, corporate, and laboratory spaces that require advanced performance from HVAC, plumbing, power, fire protection, and lighting systems. Quinn Evans Architects is multi-faceted architecture firm that has become an authority in preservation and sustainable stewardship.

With a collection that includes the 1903 Wright Brothers plane, Charles Lindbergh’s Spirit of St. Louis, John Glenn’s Friendship 7 Mercury capsule, and the Apollo 11 command module, Smithsonian administrators provided stringent requirements for the museum’s new HVAC, electrical, and plumbing systems. In addition, the more than seven million annual visitors put systems resilience, operations, and maintenance to the test. 

Rainwater Harvesting

The modernization design includes an ambitious system for rainwater harvesting. Nearly four acres of the site—approximately 165,000 square feet—consists of impervious roof and terrace areas, providing a significant opportunity to collect rainwater runoff. Two 100,000-gallon cisterns will be located at the east and west ends of the building. The cisterns will collect approximately 4.4 million gallons of rainwater a year, which will then be used for irrigation, cooling tower make-up water, and toilet and urinal flushing. 

Design of the rainwater harvesting system, anticipated to be one of the largest in the Smithsonian’s building inventory, required extensive modeling and coordination with the other architectural and engineering disciplines involved in the project. All rainwater from the roof and skylight drains, as well as air conditioning condensate, will be conveyed to the rainwater harvesting system. 

In accordance with the Smithsonian Institution Facilities design guidelines, which reference the 2015 International Plumbing Code, and for the safety of visitors and staff, rainwater from occupied areas, such as sidewalks, terraces, and other impervious surfaces that could collect undesirable runoff, will be diverted to the city storm drainage system. The collected rainwater will be conveyed above ground to the basement mechanical room and parking garage areas where it will be piped through vortex filters to provide pre-filtration and remove debris including sediment, leaves, and contaminants. The cleaned water will be directed to the underground cisterns at the east and west ends of the building. The debris and contaminants will be separated and conveyed to the city storm drainage system.  

The piping will be routed above ground through the basement parking garage and then below ground to the concrete cisterns. The west cistern will be located under a decorative fountain. The east cistern will be located under an exterior plaza. Duplex transfer pumps within each cistern will then convey the water to four 1,500-gallon day tanks located within a basement mechanical room. Domestic potable water will be used to provide a back-up water source when rainwater is not available in dry seasons. A reduced pressure zone backflow preventer will protect the main potable water distribution system from the non-potable reclaimed water. 

The harvested water will be pumped from the interior day tanks and recirculated through a self-cleaning filter and UV treatment before routing to its end use. Because of the robust filtration system selected, no chlorine or harsh chemicals are necessary. 

Quadplex booster pumps with variable frequency controllers and a hydro-pneumatic tank, piping headers. A control panel tied to the building management system interface will distribute water from the rainwater harvesting system to the irrigation system, cooling tower, public toilets and urinals, and the main staff toilets and urinals. 

Domestic Water Service

Two new water service entrances and associated reduced pressure zone (RPZ) backflow preventers will replace existing components in approximately the same location. Both services will be in the center of the parking level, one on the north wall and one on the south wall. Piping from the backflow preventers will be routed to the main mechanical room.

The two RPZ backflow preventers will include automatic shut-off valves that shut off water flow to the building if water flow is sensed being discharged through the relief chamber of the backflow preventers. Each automatic shut-off valve will include an alarm with a signal to the building automation system.

Due to the reported sediment in the municipal mains, whole-building duplex bag filters in stainless steel housing will be provided. Bag filters are sized for 600 gpm flow and have automatic change-over when filters are loaded.

A domestic water booster system will be in the main parking level mechanical room, and consist of triplex pumps with variable frequency controllers, hydro-pneumatic tank, piping headers, and a control panel with building automation system interface. The booster pump will deliver potable water to sinks, showers, electric water coolers, and other plumbing fixtures requiring potable water, domestic hot water system, mechanical system make-up, and water reclamation/harvesting system back-up.

A building water meter will be provided in each domestic water service, with a valved bypass. Separate water meters will be provided for each mechanical system make-up water connection, as well as the water reclamation/harvesting system. Water meters will be monitored by the building automation system. Additional meters for the water utility will be required for billing both water consumption and sewer usage, and also be monitored on the building automation system.

The 3D Model: Supporting Ongoing Stewardship

All plumbing systems were designed used Revit building information modeling. This enabled the Mueller Associates team to carefully coordinate the routing of the piping with other components, including structural beams and HVAC, and prepare calculations using powerful 3D imagery.

More than 20 miles of plumbing piping will be installed at the National Air and Space Museum, 1.5 miles of which will be dedicated to the rainwater harvesting gravity drain piping. An additional 1.7 miles of piping will distribute the filtered non-potable rainwater to the flush valve-operated fixtures, cooling towers, and irrigation systems. There will also be approximately 5 miles of domestic hot, cold, and hot water recirculating piping and 4.6 miles of sanitary and vent piping to and from the plumbing fixtures.  

The Smithsonian Institution is the world’s largest museum and research complex, with 19 museums and nine research centers. Recognizing that the modernization of the National Air and Space Museum has created an unprecedented opportunity to enhance its facility stewardship processes across the organization, the Smithsonian plans to use the building information model as a pilot for future museum construction projects and as an ongoing facility management tool. Following the completion of this challenging renovation, the National Air and Space Museum will serve as a model of an efficient, high-performance facility able to serve millions of visitors for many years to come.