Quality Work

Park Pacific

 

Project Overview:  Park Pacific is a 23 story historic building, with 230 residential apartments and 78,000 square feet of commercial/retail/office space.  The mechanical concept was to incorporate  a High Coefficient of Performance Water Source Heat Pump system to serve the residential portion of the project while incorporating the use of existing mechanical systems in the 1928 completed Missouri Pacific Building that was changed to the Union Pacific Building as prime office space in downtown St. Louis.  Most of the existing mechanical systems i.e. cooling towers (2) 500 ton, chillers (2) 500 ton, some air units and Trigen Steam were incorporated into the new design to serve the facility.

These systems had been replaced over the last few years from 1990 to 1995 before Union Pacific moved out of the building.  The life expectancy of the existing equipment of 30-years allowed the use of this equipment for the new system to be incorporated, which held down capital expenditures.

A new condenser plate and frame heat exchanger, loop water pumps and steam to hot water heat exchanger were added to provide the necessary heat transfer and pumping capacity for the water source heat pump system to serve the residential areas.

Due to the reduced cooling load on the chillers only one chiller was utilized to serve the commercial floors and in this application we utilized variable speed pumping on the chilled water side of the chiller to maintain the efficiency rating of the chiller.

The five existing stairwells had to be pressurized to meet current codes and several centrifugal utility type fans were added to the existing roof system to pressurize the stairwells in case of a smoke event and evacuation.

Challenges/Solutions:

Variable Speed Pumping on the Chiller System

One of the main challenges of this facility was pressurizing the main historic lobby (ground floor) and the residential corridors in case of a smoke event.  We added a 100% outdoor air unit with chilled water coil and steam coil to the 13^th floor roof area near the cooling towers to provide 100% neutral outdoor air to serve all the water source heat pumps in the residential apartments instead of utilizing operable windows.  This provided a slight positive pressure to the residential units, thus preventing city fumes, dust and dirt from entering into the apartments through operable windows and cracks in the building facade.  This also allowed for a reduction in cooling and heating requirements to the water source heat pumps.  Motorized dampers tied to a smoke pressurization system on each floor shuts off the airflow to each apartment and all the air is transferred to the exit corridors to allow occupants to evacuate the floors safely through the stairwells.  The main historic lobby was provided with new air units and outdoor dampers to allow pressurization of the historic lobby during a smoke event.