Ball State Goes Geothermal

Scientific American:

The vertical, closed-loop district system -- meaning the warm and cool water it makes does not make contact with naturally occurring groundwater -- will connect nearly 3,600 boreholes, 500-foot narrow vertical wells with loops of pipes surrounded by grout. The boreholes cover 25 to 40 acres, buried under an old soccer field, parking lots and other green fields.
The first phase began in May 2009 and became operational last November. In the second phase, the university will install 780 boreholes of the remaining 1,800 and will build a new energy station with two 2,500-ton heat pump chillers and a hot-water loop around the south portion of campus. Eventually, the system will bring heat to more than 5.5 million square feet.
The system will provide air conditioning and heating for 47 buildings on campus.
"We just keep adding to the piping the system and expanding those loops," said Lowe of the simplicity of expansion.

That is a bigass geothermal system.  So how much energy would they save if they only heated the buildings to, say 55 in the winter, and only cooled them to 85 in the summer?