How Does the Peggy Ryan Williams Center Heat

How Does the
Peggy Ryan Williams Center
Heat and Cool Itself?
The building uses a geothermal heating and cooling
system called a Ground Source Heat Pump (GSHP), or
GeoExchange. The word geothermal comes from the
Greek geo, meaning earth, and therme, meaning heat.
So, geothermal systems use heat from the earth. This
type of system uses the earth’s relatively constant
temperature of around 50º F to heat and cool a building.
The Peggy Ryan Williams Center, as seen from the front.
Photo from
Instead of creating heat like a conventional fossil
fuel furnace or boiler does, a GeoExchange
system simply moves heat around. In the winter
when the ground is warmer than the air, the
ground is used as a heat source. In the summer
when the ground is cooler than the air, it is used
as a heat sink.
This diagram shows the cycle of a Ground Source Heat
Pump in heating mode. The heat source in this picture is
the Earth, and the heat sink is the building. In cooling
mode, the process is reversed. The medium in the pump is
a refrigerant that has a low boiling point, so the heat from
the earth is enough to vaporize it.
Image from
A schematic of the underground wells. A water
and coolant solution circulates through these
underground wells and brings heat from the
Earth to the building.
Underneath the plaza of the PRW Center, there are 500
thirty-six foot deep wells. In the winter, a water and coolant
solution is circulated through these wells to gather heat
from the ground. This heat is then used to warm a liquid
refrigerant that circulates throughout the building to heat it.
In the summer, the process is reversed to take the heat out
of the building and put it into the ground.
Photo from
What is the future of GeoExchange at Ithaca
The campus’ Climate Action Plan has recently been
updated to include the possibility of replacing old
boilers and chillers with geothermal systems in
academic buildings. So, you may see more
systems like this at IC soon!
About the author:
My name is Caitlin Ahearn and I am a senior physics major here at
IC. In the summer of 2008 I received a Dana Internship to conduct
research on geothermal heating and cooling systems like this one.
I’m very interested in the environment and how we can make IC
more sustainable. If you have questions about the engineering
behind geothermal systems or the costs and benefits of installing
one in your home, feel free to contact me at!
Caitlin Ahearn 2009