Seamless retrofit of a timeless campus power plant

University of Cincinnati project designers overcome several challenges in modernizing a facility that dates from the early 20th century

By David Mercer and Nicholas Koken

At the urban University of Cincinnati, planners over the past few years faced – and overcame – several challenges in figuring out how to install additional cooling capacity at the school’s East Campus Utility Plant as a way to support growing demand. The project also called for requisite upgrade and expansion of the plant’s electrical infrastructure.

The plant, ECUP for short, is housed in a historic building and landlocked by a rapidly expanding medical center and a busy city street. The project design team was tasked with finding the most efficient way to maximize the square footage available in the existing footprint while also integrating new chilled water capacity without disrupting service or the flow of traffic around the site.

The team was able to accomplish all major project goals and deliver reliable chilled water generation in time for peak 2024 cooling demand while at the same time leaving the system in an easily expandable state that allows the university to react quickly as cooling requirements continue to grow.

REDESIGNING AND RETROFITTING WITHIN ESTABLISHED CONFINES

The university has two plants that serve a 470-plus-acre campus community that includes over 53,000 students and more than 120 buildings, as well as a number of local hospitals.

The ECUP is one of the school’s oldest buildings, constructed in 1911 to house coal-fired boilers to generate heat and electricity. It has been adapted over the years to support UC’s changing needs, including the addition of a thermal energy storage system buried just outside the plant. In 2023, further renovations increased its chilled water capacity and efficiency. On that project, RMF Engineering redesigned a portion of the plant within its existing architecture, balancing modernization with historic sensitivity.

ECUP’s layout is segmented into zones, with chillers in one area of the building and boilers in another. RMF performed an initial study to develop the optimal sizing of new chillers and auxiliary equipment to support the increased loads within the available square footage. The study also included an evaluation of the existing medium voltage distribution system and analysis of existing plant electrical loads.

The resulting plan tactfully fortifies and reorganizes the structure to accommodate 6,000 tons of additional chiller capacity, replacing outdated equipment and repositioning defunct features for modernized controls and improved maintenance access. The project included the installation of two 1,000-ton variable-speed magnetic bearing chillers, and the design included provisions for future installation of the remaining 4,000 tons in the future. Full buildout requires a 2,000-ton chiller and a second pair of 1,000-ton chillers.

A two-cell cooling tower was placed on the roof to serve the new chillers, with structural steel and condenser water headers installed for additional towers to support the full buildout. Together, these upgrades and configuration changes position the plant to seamlessly add additional capacity with few, if any, service interruptions as more chillers other parts of the building reach the end of their useful lives.

The project was broken into phases, beginning with demolition and structural steel work to prepare for the new chillers as well as the associated cooling towers, pumps, control-system modifications and piping needed to tie the new equipment into the active distribution system.

Obsolete coal-handling and roofmounted pollution control equipment was removed, and the large baghouse opening through the roof was repurposed as an access hatch to the new switchgear room, which is situated on a new mezzanine above the chillers. RMF’s structural engineers were able to take advantage of an existing storage room located above a portion of the plant and design it for new electrical gear storage. They were able also to utilize existing steel to carry the load of the new cooling towers. Careful structural modifications were made to accommodate new rooftop equipment, with special attention paid to the plant’s historic architecture. The building’s cultural significance created a number of challenging limitations on what could be done without changing much of the exterior or removing anything from the structure.

All new ventilation and exhaust fans were roof-mounted to avoid affecting the sides of the brick building, which are visible from the street. RMF also worked with SMP Design to address occupancy and egress, fire ratings and other lifesafety code requirements. The design maintains the aesthetics of the original facility, while allowing for repurposing "behind the façade."

INTRODUCING THE NEW CHILLERS AND POWERING THE RECONFIGURATION

The new cooling equipment was sited in a portion of the plant’s former boiler room, where RMF had already removed steam-generation equipment as capacity needs were reduced. A new interior wall now separates a remaining natural gas-burning boiler from the new chillers, equipped with a detection system that activates an emergency ventilation system in the event of a refrigerant leak.

As a part of the design, RMF hydraulically modeled the existing and new plant piping systems to ensure that pump heads and flow rates were capable of supporting the proposed additional capacity and the new equipment could operate in parallel with the existing plant.This allowed the headers for the new chilled water equipment to be cross-connected with the existing one, enabling any new chiller or pump to be integrated seamlessly. The new chillers can also be used to charge the existing TES system.

By removing old ash-handling equipment from the basement of the plant, space was created to relocate the existing chemical treatment equipment that serviced the condenser water, chilled water and steam generation systems. Sample-testing stations and ventilation systems were also installed for the new chemical storage room.

Tie-ins to the chilled water system were coordinated for wintertime low-load periods to allow for limited disruptions to the medical center. Given ECUP’s proximity to the busy Eden Avenue, detailed maintenance of traffic plans were developed to safely control vehicular and pedestrian traffic when heavy equipment was being lifted for installation.

RMF’s initial power study covered all new and existing electrical equipment in the plant, from the medium-voltage distribution down through the lowvoltage disconnects, to assess the existing conditions and loads. The study also included a short-circuit analysis, protective device coordination, load-flow analysis and arc-flash analysis.

To accommodate the equipment upgrades, the electrical design was also updated to include new 15kV switchgear to replace the existing outdoor gear, which had reached the end of its useful life. A new 480V single-ended substation with space to install the second half of a double-ended substation was also designed to serve the new chillers, pumps and cooling towers. A new climate-controlled room was built on the expanded mezzanine to house the upgraded electrical equipment along with a 125VDC battery room, all the 480V pump and tower motor VFD’s, low-voltage distribution panels, HMI-based control station, RTAC and telecom rack.

Moving all the critical electrical gear into a new indoor space will allow for easier maintenance and longer service lives for the new equipment.

David Mercer, PE, oversees regional mechanical design for RMF Engineering on central utility plant and thermal distribution projects, including design and evaluation of steam and chilled water generation and distribution; automated mechanical systems; metering upgrades; and water systems. He has a degree in mechanical engineering from Ohio State University. david.mercer@rmf.com

Nicholas Koken is an RMF mechanical designer specializing in the analysis and design of steam and chilled water generation, distribution and boiler plant systems. He also does campus utility tunnel assessments, replacement of mechanical equipment, and piping-system stress analyses. He holds a mechanical engineering degree from Ohio State University. nicholas.koken@rmf.com