Ohio college saves $60K in energy costs with green HVAC
Thanks to its new geothermal system, the University of Findlay’s Davis building, located in Findlay, Ohio, is gaining plenty of recognition — and energy savings.
Officials say the green HVAC system is saving the 42,000-square-foot building 57 percent more energy than traditional systems, which translates annually into $59,000 in reduced energy bills and $7,500 in reduced maintenance. This is partially due to the system’s active chiller beams provided by Semco LLC.
The building’s geothermal system supplies 58°F to 62°F closed-circuit, ground-source water to the chillers.
Consulting engineer Stephen Hamstra said the geothermal chiller system saves a significant amount of energy, compared with traditional systems.
“We see a tremendous opportunity with chilled beams and geothermal, especially north of the Mason-Dixon Line where inherent ground temperatures of mid-50s (degrees Fahrenheit) can be used in chilled beams and radiant systems,” Hamstra said. “Instead of the 20 EER (energy efficiency ratio) of a conventional chiller system operating a majority of the time, the University of Findlay system achieves an estimated 150 to 200 EER.”
The 60-ton magnetic bearing chiller, manufactured by Smardt of Plattsburgh, N.Y., runs about 20 percent less and is four times smaller than a conventional chiller in a similar-sized building, which helped reduced the project’s equipment capital costs, officials added.
Installed by Findlay, Ohio-based mechanical contractor Jack’s Heating A/C & Plumbing, the chilled beams have adjustable nozzles to address specific areas in its airflow range. The balance of air and water temperatures are all controlled by the Niagara platform building automation system manufactured by Tridium of Richmond, Va. Hamstra also supplied each chilled beam room with a localized hot-water reheat coil, manufactured by Trane.
“We reset the DOAS (dedicated outdoor air system) discharge temperatures based on what most zones are calling for,” Hamstra said. “The localized reheat coils can provide a more precise temperature required in that particular zone.”
The outdoor air supplied through the active chilled beams also prevents potential floor condensation from the radiant system, officials say. Hot water for the chilled beams and radiant system is supplied via chiller condenser heat recovery. An adjacent campus building’s conventional boiler serves as a backup, if needed.
“I think the chilled beams will continue to take market share from heat pumps in geothermal designs,” Hamstra said. “However, designers must consider condensation and humidity control along with DOAS. Another important consideration is getting the greatest capacity and efficiency from a geothermal system by using the warmest water temperatures possible for cooling and the coolest for heating.”
The Davis building’s geothermal system also included Greensleeves’ software, which provides several levels of predictive control based on the present and future temperature and humidity conditions of the building load, loop and outdoor environment, while also managing the geothermal bore field. For example, the software might signal the chiller to increase the temperature of the radiant’s thermal mass on a morning where trends predict additional cooling will be needed in the afternoon.
“The software perpetually runs building load analytics and then reprograms itself every five days for better efficiency in a self-adapting approach.” said Hamstra.