The goal of installing an hvac system that would outlive a traditional system of boilers, chillers, and rooftop units was the idea of Fred Fries, business manager for the new school. But the idea was not a popular one, at least not at first.
“We met with resistance from every engineer and architect involved in the project,” said Fries. “But I was looking for a system with a lifespan longer than what rooftop units would provide, a system with many individual zones and one that is efficient.”
“I actually had to have the entire team tour another area school with geothermal so they could see the results in black and white,” Fries continued. “We reviewed all the school’s data that related to hvac efficiency and cost savings. Everyone was amazed at the efficiencies and savings, to say the least.”
The Nuts and Bolts of GeothermalGeothermal heat pumps use the Earth’s energy storage capabilities to heat and cool buildings and to provide hot water. The earth acts as a huge energy storage device that absorbs 47% of the sun’s energy – more than 500 times more energy than is needed each year – in the form of clean, renewable energy.
Geothermal systems function by moving heat that has been extracted from the ground, rather than by converting chemical energy to heat (like in a traditional furnace). A geothermal system consists of an indoor unit, or ground source heat pump, linked to an external heat exchanger, earth connection, or ground loop, buried in the ground.
The inherent benefit of a geothermal heating and cooling system is the abundance of heat that is stored in the earth. In the winter, water circulating through the ground loop is heated in the earth and the heat is extracted as the water is passed through the evaporator of the heat pump. It is then compressed to a higher temperature and released into the building. In the summer, the system is reversed – heat is pulled from the building and returned through the water into the ground.
Geothermal systems require the installation of a loop or well field. The water that circulates through pipes buried in the ground carries the energy from the soil to the building in the cold weather and from the building to the soil in warm weather. The ground is used as the energy transfer station. Air-handling units and/or heat pumps will circulate the air through vents to provide heating or cooling to the building.
According to Fries, “An advantage of a geothermal heat pump system is comfort and controllability. We can accurately control the atmosphere in each one of the rooms as well as the ambient temperatures. We are able to control the ambient temperature for each room and to program each room individually years in advance. This gives us ultimate control over scheduling of the building which will be used by community groups in addition to its regular high school functions.”
Appearance and maintenance are other significant benefits of the ground source heat pump, which appealed to Fries. Five rooftop units are used to temper outside as opposed to more than 20 units with a conventional design. The heat pumps are located within the facility and are not subject to the harsh summer and winter conditions like a rooftop unit.
Upon investigating the geothermal option for Barberton High School, Fries discovered that the location of the new high school had soil with excellent thermal conductivity.
According to Fries, the real advantage of the system is the expected length of time it will be effective, which is 30 to 40 years. In contrast to rooftop units that may need to be replaced every 15 years or so, the geo-thermal system is expected to be relatively carefree. Routine maintenance will include the changing of filters and maintaining the compressors.
The Control FactorHvac controls for the new Barberton High School were provided by Novar Controls (Copley, OH). Hvac controls are built on Novar’s Logic One™ system, a network of standalone modular components that allow the system to be customized to meet each building’s unique control and monitoring requirements. Intelligence is distributed so that each module can stand alone or work as part of the overall system.
Specifically, the control system at Barberton High School consists of six EP/2 executive processors, 180 HPC+ heat pump controllers, and 49 IOM/2 input/output modules that are managing 1,096 tons of cooling capacity. The input/output modules provide flexibility with additional control points to control the complex heat pump loop pumping system, air-handling units, makeup air units, exhaust fans, lighting, and other miscellaneous equipment.
Novar customized a controller for the heat pumps as well as outfitting Logic One™ with their SitePro Graphic Infosystem.
With SitePro, Fries can check the system each morning from his PC. SitePro provides full-color displays of temperature, pressure run-status and other real-time information, overlaying this data on actual photos of buildings, equipment, or aerial views of facilities. These monitoring tools offer control over buildings, processes and equipment for maximum system efficiency.
With these controls in place, Fries may routinely check the comfort levels of every room in the Barberton High School building as well as the heat pump loop temperatures and the operating conditions of the loop pumping system. “Thanks to an Ohio winter, the staff was able to experience the comforts of the new system almost immediately,” said Fries. “Everyone agreed that the school has an excellent comfort level. The staff is pleased, not to mention warm.” ES