At a 43-year-old school building in Winchester, Kentucky, a recent HVAC retrofit helped the school district save money and energy by reusing and upgrading its outdated piping system.
Robert D. Campbell Junior High School, a part of Clark County Public Schools, was retrofitted in 2015 from outdated unit ventilators to chilled beams and dedicated outdoor air systems. The update, officials said, established the school as the world’s first to use smart, plug-and-play controllable chilled beam pump modules, which has helped save hundreds of thousands of dollars in capital equipment, labor and installation costs.
The pump modules used in the school’s two-phase HVAC retrofit saved the school district $147,000 in labor installation costs when compared with the costs of variable refrigerant flow technology, officials said. The total labor and installation cost of the chilled beams was $599,000. The cost of using variable refrigerant flow would’ve been $746,000, according to an itemization compiled by engineers and school officials.
The combined chilled beam and dedicated outdoor air system will also save the school $33,000 annually. The energy savings are also expected to lower capital dollars spent on the project by $500,000, which is guaranteed by a performance contract with Indianapolis-based Performance Services Inc., an integrated design and delivery engineering contractor that led the project out of its Lexington, Kentucky, branch.
The contractor’s controllable chilled beam pump module specification allowed the reuse of 100 percent of the original piping, boiler, chiller and pumps. The use of the modules also eliminated the need for heat exchangers and the guesswork associated with chilled beam system specification, installation, balancing and commissioning.
Even with fluctuating, seasonal temperatures, the design provides tempered conditions within a one-degree tolerance — regardless of season — because the control is based on outdoor dew point, not temperature, according to Columbia, Missouri-based HVAC product manufacturer Semco LLC. The company manufactured the project’s 46 Neuton controllable chilled beam pump modules, 212 IQHC active chilled beams and the Pinnacle 5,000-cubic-feet-per-minute dedicated outdoor air systems.
Planning and installation
Chilled beams in school retrofits offer superior air comfort and lower costs compared with variable refrigerant flow systems, said Gary Sprague, Performance Services Inc.’s energy management specialist and Campbell project manager. Clark County School District Superintendent Paul Christy said he also saw the benefits of a hydronic-based system, which has three times the lifecycle expectancy and lower maintenance costs than variable refrigerant flow systems.
Morehead, Kentucky-based Donahue Mechanical, the project’s sheet metal and piping contractor, reused the hydronic trunk lines and former unit ventilator taps for the first floor, but needed to extend the second floor unit ventilator taps to the ceiling for the controllable chilled beam pump modules and chilled beam connection. Most of the modules on each floor are mounted above the classrooms’ 18-inch, high T-bar drop ceilings and control four ceiling flush-mounted chilled beams that range from 2-by-2-foot to 2-by-8-foot sizes.
“Our project is best described as a three-loop system,” said Sprague, who has experience managing several previous chilled beam projects. “The takeoff loop to and from each CCBPM (controlled chilled beam pump module), and the loop that connects a series of four to eight chilled beams to its respective CCBPM.”
The third loop, Sprague explained, is a “game changer” because the module blends and recirculates the return water within its zone to convert typical 42°F and 140°F primary loop supply water temperatures to optimal 58°F or 100°F chilled beam discharge temperatures, respectively. This prevents cooling-mode condensation and heat-season thermal stratification.
The facility’s building management system is supplied by Surrey, British Columbia-based Delta Controls Inc., with front-end software by Richmond, Virginia-based Tridium. The software monitors the modules via Ethernet and sends outdoor temperature/humidity information.
Christy, who also pushed for the installation of chilled beams specified with geothermal green HVAC and dedicated outdoor-air systems at the district’s George Rogers Clark High School, said an added bonus of the upgrade was a reduction in mechanical noise and a boost in student attendance.
“The two-pipe conventional unit ventilators that preceded the retrofits were noticeably loud and distracting, whereas now I walk into classrooms with the chilled beams and I can’t hear any sound from the HVAC system.”