The trend in the U.S. shows downtown metro centers growing substantially, and Des Moines definitely reflects that trend. Today there is a residential renaissance of people who are moving back to the city or the center. Liberty Building is the essence of life in the city center, and the ownership group felt the need to bring this opportunity to Des Moines. This historic site is now a mixed-use building and boasts office and retail space and hotel accommodations.

A complete interior demolition had to be performed first to expose old structure and make room for new modern construction as well as state of the art high efficiency mechanical systems. The desired mixed-use consisted of bottom and top floors to remain as retail/class A office space and the middle floors to be high end living quarters. This mixed-use requirement in an old structure required different mechanical systems for optimum efficiency.

Retail/office levels were designed with RTU’s, variable air volume systems with electric reheat, and DDC Controls.  Ductwork systems varied (both exposed and concealed above ceilings).

Residential levels were designed with self contained ceiling hung Fan Coil Units piped from roof mounted Chiller and ducted above gyp board ceilings. Other new building components consisted of a new 12 story trash chute, and a new stairwell pressurization exhaust system for a new 12 story stairwell. Several existing building tenants remained active in the building on various floors during construction causing careful critical planning to not disrupt their normal day-to-day operations – especially with new HVAC systems.

Parking ramp consisted of electric heaters in elevator lobbies and a plumbing pipe storm drain system.

The ownership group required optimum ceiling heights (10 ft) in living quarters and wanted mechanical systems concealed with fresh painted hard gyp board ceilings. No exposed ductwork or plumbing. This required careful planning of flatten ductwork, piping, and HVAC unit locations. Also, since a historic preservation building, exterior skin of the building had to remain as is – not allowing exterior mechanical vent penetrations – and basically dictating specific mechanical systems for high rise construction.

A very fast track schedule demanded quick turnaround designs, precise fabrication, and high quality installations in an 85 year old building whose structure was complex and varied floor to floor. Major building demolition of existing interior materials had to be completely removed in order for new modern mechanical systems to be installed. A lot of field verification was required due to the varying structure on different floors to allow for optimum heights.