Gannett Fleming: Shippensburg University Central Plant

New construction at an educational facility.

08/14/2014


Proposed chilled water facility at Shippensburg University. Courtesy: Gannett Fleming Engineering firm: Gannett Fleming
2014 MEP Giants rank: 40
Project: Shippensburg University Central Plant
Address: Shippensburg, Pa., U.S.
Building type: Educational facility
Project type: New construction
Engineering services: Automation/controls, electrical/power, HVAC/mechanical, lighting, energy/sustainability, and plumbing/piping
Project timeline: 1/3/2011 to 6/1/2015
MEP/FP budget: $25,200,000

Challenges

Keeping students and faculty comfortable and safe while keeping costs low were central themes to Gannett Fleming’s development and implementation of a new central cooling plant for Shippensburg University in Shippensburg, Pa. Work included the simultaneous decommissioning of an existing central heating plant and installation of a more efficient de-centralized clustered heating plant strategy. The work also included the coordination of the associated heating/cooling distribution piping systems. Special consideration was given to the operational calendar of this higher education institution. To avoid disruption to the staff’s and students’ schedules, and to take advantage of the heating and cooling seasons, Gannett Fleming designed the new infrastructure so that it could be constructed on a fully operational university campus. New heating boiler systems and underground heating hot water and steam piping were installed during the late spring and summer when classes were not in session. The new central chillers and chilled water piping were installed during fall and winter without disruption to the class schedule. Further complicating the construction schedule, portions of certain buildings were closed off during the demolition of the existing steam heating equipment, allowing for the installation of new hot water heating boilers, associated pumps, controls, and piping. Where steam was used for both building heating and domestic hot water generation, Gannett Fleming adopted a phased approach to temporarily relocate the existing systems to minimize service interruptions. Four new boiler rooms were created, and each will eventually serve a cluster, or “neighborhood,” of buildings. Where clustering did not make sense, local boiler rooms were added and new boiler systems provided to meet the heating requirements of those buildings. In all of the campus buildings with hot water heat, the existing steam-to-water convertors and associated equipment had to be removed, and the existing building heating system reconnected to the new distribution system piping. Additionally, there were seven campus buildings that never had been converted from steam heat to hot water. To support these buildings, new steam boiler and distribution systems also were provided. Sequencing these activities was critical to the success of the project. Another challenge involved upgrading the existing buried natural gas distribution system to allow for the added loads of gas-fired hot water boilers, which will replace the antiquated coal-fired central steam plant and distribution piping. To meet this challenge, a new service connection to the campus grid was made and a new gas meter installed. In locations where additional pipe capacity was needed, parallel lines were run to minimize service downtime and construction costs. These new lines were sized with an eye to the future in anticipation of campus developments. One of the most important challenges addressed was how to maintain a safe environment for students, faculty, and visitors to the campus throughout the construction activities. Per contract requirements, contractors provided alternate routes for any sidewalks or pathways that were temporarily closed, and they fenced off and marked all excavation work.

Proposed chilled water facility at Shippensburg University. Courtesy: Gannett Fleming Solutions

Shippensburg University originally planned to replace the existing coal-fired steam plant with a modern natural gas-fired plant, and to provide new distribution piping to serve the campus facilities. Although coal is a relatively inexpensive heating fuel, the costs of maintaining the 60-plus-year-old steam plant, as well as the escalating costs of meeting environmental regulations, drove the decision to move to natural gas. The university’s plan also included the construction of a new central cooling plant and chilled water distribution system, and removal of existing local air-cooled and water-cooled chillers that provide air conditioning in most buildings. Gannett Fleming completed a basis of design study during the programming phase of the project. The study results indicated that significant construction cost savings could be generated by designing a de-centralized heating system in lieu of a central plant system. Six buildings were chosen as locations for new heating hot water boiler rooms, with each boiler room supplying underground hot water piping to serve a cluster of nearby buildings. Throughout the design process, some of these clusters were merged, resulting in four heating clusters and four buildings with stand-alone building heating systems. The boilers are high-efficiency and are designed with sufficient redundancy so that the loss of a boiler does not affect its ability to meet space heating needs. New boiler controls are integrated with the existing campus BAS, as is all-new heating and cooling equipment, to allow full control of hot water supply temperature to maximize the advantage of the high-efficiency boilers. The new central cooling plant was designed to meet current building loads, with redundancy and capacity for the five-year projected capacity requirements. Three 1,000-ton variable frequency drive electric drive chillers will be installed. Space in the plant is allocated for a future 1,000-ton chiller, along with space for an additional cooling tower cell. The plant configuration is expected to handle the load requirements projected 20 years ahead. In addition, the basis of design study demonstrated the economic feasibility of designing a thermal storage tank as an integral part of the chilled water system. A 2-million-gal above-ground storage tank will allow chilled water to be generated during off-peak hours, such as overnight, to provide 4 hours of full-load capacity without the need for mechanical cooling. Further, an existing 500-ton packaged air-cooled chiller will be relocated adjacent to the new central plant to provide for low load operation and additional redundancy if needed. The operation of all chillers and associated equipment will be optimized through the BAS control logic.



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