Model Geothermal Installation Supports Habitat For Humanity Development

By Jeff Griffin, Senior Editor | June 2010 Vol. 65 No. 6
Vertical drilling to install the geothermal closed loop pipe. HDD and trenching are also sometimes used.

Hope Crossing, a suburban housing development in northeast Oklahoma City, may not look much different than other housing additions of attractive, moderately-priced homes, but it is unique. Hope Crossing is the largest “green” Habitat for Humanity housing development in the United States, and it is believed to be the only Habitat multi-dwelling project in which all homes are served by geothermal heating and cooling systems.

More than half of the development’s 217 homes are complete and occupied with construction of the remaining houses scheduled to be complete by 2013.

The Central Oklahoma Habitat for Humanity (COHFH) development occupies a 59-acre tract in northeast Oklahoma City. Three-and four-bedroom, two-bath brick homes average 1,250 square feet of living space. Each home is equipped with a geothermal system using the earth’s relatively constant underground temperature to heat the home in the winter and cool it during hot weather.

Rather than conventional forced air heating and cooling systems, every home will have a ground source heat pump with integrated pumping and purging valves connected to a 400-foot-deep HDPE pipe loop. Water circulates through the system, drawing heat from the earth in cold weather and reversing the process in summer to extract heat from the house and dissipate it in the ground.

Greatly reduced heating and cooling costs are the primary benefit to home owners, said Ann Felton, COHFH chief executive officer. Hope Crossing residents say they are paying about half the amount of their past bills for heating and cooling a comparably-sized dwelling. Some report savings of even more.

The Habitat for Humanity program is well known for efforts of volunteer individuals and partner organizations who donate time for labor and materials and products to construct and outfit homes.

ClimateMaster, Oklahoma City, the world’s largest ground source heat pump (GSHP) manufacturer, donated Tranquility 20 Series GSHPs for every house in the Hope Crossing project. Drilling ground loops and installation of the GSHP system is done by Comfortworks, an Oklahoma City-based ClimateMaster dealer and contractor.

Getting started
The first step in installing the system is drilling the 400-foot vertical loop. A truck- mounted vertical drill does the job before construction on a home begins.

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