In Asphalt to Ecosystems (New Village Press, 2014), author Sharon Gamson Danks shares some of her knowledge about increasing the use of renewable energy in schools around the United States and around the world. Her methods are not only energy efficient, but they serve to educate the children within the schools as well. This excerpt, which centers on geothermal heating and cooling systems inside of schools, is from Chapter 6, “School Energy Systems.”
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Geothermal Heating and Cooling Systems in Schools
Some school buildings are designed to take advantage of geothermal energy. The temperature of the earth, deep in the ground, remains fairly constant throughout the year even when the air temperature experiences wide fluctuations from winter to summer. This constant ground temperature varies by latitude but is generally between 45 degrees f—75 degrees f at a depth of six feet. Geothermal heating and cooling systems are designed to take advantage of this thermal constant by pumping air or water into the ground to be heated or cooled to the earth’s stable temperature. Once the ground warms or cools the circulating air or water, it takes very little extra energy to bring it to the desired temperature for a comfortable building. The conditioned air or water may then be used in radiant heating or cooling systems embedded in the building’s floors, or as part of the building’s HVAC (climate control) systems. Geothermal climate control systems make buildings more comfortable and may save their schools a substantial amount of energy as compared to conventional heating and cooling options. These systems have reasonably short payback periods, generally take up less room in the school than conventional heating and cooling equipment, and run quietly.
Twenhofel Middle School in Independence, Kentucky, has a geothermal heating and cooling system that uses only half the energy of a typical climate control system. Each classroom can adjust its own temperature independently to maximize comfort. The building includes a “truth window” in the science lab’s ceiling so students can see the climate control system’s ducts and other utilities.
In 1997, the architecture firm, White Arkitekter, helped Östratorn School in Sweden to create a large school building addition that includes many innovative green building techniques. The overall building design incorporates passive solar features including numerous surfaces made from concrete and brick, which absorb heat and help to moderate the temperature inside. Awnings are placed strategically on the east and west sides to reduce indoor temperatures in the spring and summer. The building relies heavily on daylight as a primary lighting source, so it avoids much of the typical heat gain that results from standard lighting fixtures. It also has a radiant heating and cooling system.
One of the most innovative features of the building’s design is its energy efficient, geothermal ventilation system that heats and cools the classrooms. The building’s ventilation system takes in outside air and channels it into conduits underground where the temperature is always a moderate 46 degrees f (8 degrees Celsius). This ground temperature either cools or preheats the air, depending on the season, and the conditioned air is circulated through the building’s ventilation and radiant flooring system.
During the summer, warm outside air is drawn through the underground conduit to cool and then is released into the classrooms. The cool air cools the concrete floors which, in turn, keeps the rooms cool even after the conditioned air has left the space.
In the winter, the moderate-temperature underground preheats the freezing outside air before it enters the building’s heating system. At that point, it takes very little additional energy to actively heat the air to a comfortable temperature for the building’s occupants. Again, the warm air is circulated through pipes in the floors before being released into classrooms, warming the thermal mass of the floors so that they continue to radiate heat after the warm air in the ventilation system has left the room. Each of the classrooms has a set of controls to increase or decrease the airflow in the room and operable windows that do not interfere with the ventilation system.
Want more ideas from Asphalt to Ecosystems? Learn how schools in California are Making a Green Schoolyard Out of Natural Building Materials.
This excerpt has been reprinted with permission from Asphalt to Ecosystems: Design Ideas for Schoolyard Transformation, by Sharon Gamson Danks, published by New Village Press, 2010. Buy this book from our store: Asphalt to Ecosystems.