Co-Authors: Athi Toufexis & Rick Petricek
Green. LEED. Sustainability. Climate change. Environmentally-friendly. Renewable. Geothermal. Chances are you’ve heard one of these buzzwords in the last month, week, or maybe even the last day. But what does it all mean? How are our schools and school architects addressing these issues?
With aging HVAC building systems and continued costly maintenance, school districts are frequently faced with the decision of needing to update their buildings’ heating and cooling systems. Traditionally, a school’s HVAC system has been comprised of boilers, air handling units, and individual unit ventilators in each classroom that are centrally controlled. These systems don’t allow for cooling, humidity control, or individual temperature control by room. All of these conditions contribute to a learning environment that can be uncomfortable for students and faculty, alike.
Over the last 5 years, StudioGC has assisted four school districts in replacing existing HVAC systems that were reaching the end of their lifecycles with new, one-pipe geothermal heating and cooling systems. Seven schools are currently fully operational, with another 10 schools under construction (see link to: WASD project page). So what’s this new geothermal system all about?
Geothermal systems use the consistent temperature of the earth (approximately 55 degrees) to provide heating in the winter and cooling in the summer. A loop field, ranging anywhere from 50 bores for a smaller school to 400 bores for a large high school, is installed at existing playing fields, playground space, or even a school’s parking lot. The bores are each about 400’ deep and are comprised of piping filled with a water and glycol solution that assists with heat transfer with the earth. No material from the earth is removed in this process, and no solution or liquids are added to the earth. The play or parking areas are restored after the completion of the bore field to their previous states, and again become usable surfaces for the school.
Within the building, a one-pipe continuous loop is installed to circulate the solution between the school and the bore field loop. The pipe solution exits the school and circulates through the loop, releasing excess heat into the earth during the summer months, and reversely absorbing heat from the warmer earth during the winter months. The cooler or warmer solution is then circulated through the school’s one-pipe system to individual heat pump units serving each classroom, where it is released as heating or cooling. Each faculty member can customize the temperature at the heat pump within their own rooms independent of other rooms in the school. The heat pumps not only provide heating, like a traditional unit ventilator, but they also provide cooling and humidity control utilizing the same piece of equipment. A one-pipe geothermal system has a lower initial cost than other geothermal systems and realizes efficiencies from different rooms within the school that may require heating and cooling at the same time.
By taking advantage of the earth’s natural resources, geothermal systems are providing annual savings of approximately 50% on a school district’s energy bills. MacArthur Middle School, the first school in Prospect Heights School District 23 to turnover to geothermal in their district-wide replacement, realized 61% energy savings in their first year of operation. Faculty and students have an enhanced learning environment that is more comfortable, less noisy, better ventilated, and with better control of allergens. School districts and students mutually benefit from the installation of geothermal systems.