LOCATION
Lincoln, Nebraska

AREA
600,000 GSF

PROJECT DESCRIPTION
Alvine Engineering is the mechanical, electrical, and plumbing (MEP) engineer-of-record responsible for the Nebraska State Capitol (NSC) HVAC Replacement and Window Restoration Project. The restoration project consists of a seven-phase renovation that includes two pre-construction design phases and five phases of construction. The high-rise Capitol is a registered historic landmark with highly ornate preservation areas, including the State Supreme and Appellate Courts, the Governor’s office suite, and legislative chambers. The building has a three-story base pedestal and a high tower ending on the 15th floor below the dome.

PROJECT HIGHLIGHTS

• The team executed extensive fieldwork to investigate mechanical and electrical routing through this building ahead of and during design work. Close consultation with the Capitol architect helped direct the routing and secure approval for the historic and aesthetic requirements.
• New Variable Refrigerant Flow (VRF) system will serve over half of the building. The VRF consists of floor-set console fan coil units (FCUs) and horizontal soffit-located FCUs served by a geothermal wellfield connected to water-cooled/heated indoor condensing units. Both heat pumps are used in the building’s HVAC heat recovery technology design.
• Careful attention during design afforded placement of many console units in existing historic cabinets below windows and concealing horizontal FCUs in existing/expanded soffits. The piping systems serving the FCUs include insulated refrigeration and condensate, as well as power and control conduits. The base three floors are kept out of sight through careful routing above the historic plaster ceiling, in plaster walls, in the unfinished basement (below the first floor), and in attic spaces for the upper base floors.
• The condenser water system is heated and cooled by a remote geothermal well field. The water-cooled condensing units are strategically located out of sight in mechanical room spaces throughout the building. Condenser water piping is likewise routed out of view in wall cavities and reclaimed shafts.
• A 510-ton heat recovery chiller produces heating and cooling water. This modular chiller can simultaneously produce both. This highly efficient primary equipment works best in partial load conditions, which is most of the year. It will provide chilled water in winter for preservation spaces, mechanical/electrical rooms, and other spaces that cannot readily use outdoor air-free cooling.
• Hydronic pumping design utilizes new technology, such as multi-pump and variable-speed skid packages. These factory-assembled pump skids have three or more vertical turbine pumps piped together and controlled to allow the most efficient combination of pumps and operating points possible for constantly changing building loads. Significant energy savings are realized compared to single pumps with variable-frequency controllers.
• Air handling units with chilled water and heating water coils were provided to serve assembly spaces. Demand-based ventilation control using CO2 sensors allows for energy conservation when occupancy is low or absent.
• Refurbished approximately 170 steam radiators.
• All new digital Building Control Systems replaced original pneumatic controls.
• Fire sprinklers were installed on three base floors, and sprinkler installation was finalized in other unprotected areas.
• Fully replaced fire alarms. Preservation areas have aspirating smoke detection (VESDA-Very Early Smoke Detection Apparatus) fire alarms.
• The lighting scope included restoring some interior historic fixtures and replicating missing fixtures. Other lighting work was required to support the HVAC work.

Photography credit: Kessler Photography