The Circular Congregational Church, recently featured in an article in AIArchitect titled "Greening God's House," is an example of the wide-ranging appeal of sustainable design technology. Michael Crosbie, the article's author, believes that the concept of green structures appeals to religious congregations because "stewardship is a key part of their mission." Circular Congregational utilizes proven technologies like a green roof, geothermal heating and cooling systems, a rainwater collection cistern for landscaping use, and recycled building materials.
The geothermal HVAC is particularly useful in Charleston, where electricity bills can reach astronomical levels in the summer when it may be necessary to cool a large building. Geothermal takes advantage of the naturally sustained core temperature of the earth itself to accomplish that task much more cheaply. About four feet below the surface, the ground maintains a year-round temperature of around 50 degrees Fahrenheit; pipes buried at that depth circulate liquid which is then used to heat or cool air in the surface system to be pumped out through vents. This cuts back significantly on the amount of energy needed for climate control (up to 50 percent); proponents of the geothermal systems claim that they pay for themselves in as few as two to seven years.