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HOW THE SYSTEM WORKS
(Source: New York State Energy Research
and Development Authority)
A conventional heating and cooling system uses a fossil
fuel-fired boiler to add heat to a water loop (winter heating) and
a cooling tower to expel heat from the loop to the air (summer cooling).
Geothermal heat pumps transfer heat between the constant temperature
of the earth and the building to maintain the building’s interior
space conditions. Below the surface of the earth throughout New
York, the temperature remains in the low 50° F range throughout
the year. This stable temperature provides a source for heat in
the winter and a means to expel excess heat in the summer. With
geothermal heat pump systems, water is circulated between the building
and the “ground-loop” piping buried in the ground. In
the summer, the water picks up heat from the building and moves
it to the ground. In the winter, the fluid picks up heat from the
ground and moves it to the building. Heat pumps make the collection
and transfer of this heat to and from the building possible.
Geothermal pump systems exchange thermal energy between a building
and the ground. When the building needs heating, the system extracts
heat energy from the ground and pumps it into the building where
it is boosted by the heat pump to a comfortably warm temperature.
Conversely, when the building needs cooling, the heat from the building
is collected by the heat pumps and sent into the ground, much as
a refrigerator’s compressor transfers heat from inside the
refrigerator to the outside. This exchange of thermal energy makes
the system efficient. Rather than creating heat by burning a fuel
on site or chilled water by expelling heat to the hot summer air,
the geothermal heat pump system moves thermal energy between the
ground and the building using heat pump technology.
The relatively constant temperature of the ground makes this energy
transfer efficient throughout the year, even during the coldest
weather. When the building needs cooling, the system takes advantage
of the relatively constant ground temperature that is usually cooler
than the outdoor air in the summer. Alternative systems must move
energy from the building to the hotter outdoor air, while the geothermal
heat pump system gains efficiency by transferring the energy to
the cooler ground.
COST AND ENERGY COMPARISON
The geothermal heat pump system is estimated to cost $350,000, slightly
more than the installation of a conventional heating and cooling
system. However, a conventional system would require a gas line,
boilers, boiler stack, cooling tower, support steel, plate and frame
heat exchanger and additional pumps, incurring offsetting costs
of approximately $150,000, a differential of about $200,000. The
College anticipates a $35,000 rebate from the New York State Energy
Research and Development Authority (NYSERDA) and additional rebates
based on “green” building systems and lowered energy
use.
Past experience with similar buildings and comparisons between
conventional and geothermal energy use suggest that the College
can expect annual energy savings in the range of $35,000 and annual
savings in maintenance and staff time of about $15,000. When calculating
additional costs over annual savings, the system will pay for itself
in 3.3 years and will continue to save energy and money over the
life of the building.
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The College of Saint Rose will use
a geothermal heat pump system designed by Friedman Fisher Associates,
PC of Latham to provide all of the heating and cooling needs of
the Massry Center for the Arts.
A geothermal heat pump system taps the constant temperature of
the earth to provide efficient heating and cooling. The system uses
water-source heat pumps within each room that can heat and cool
the building spaces simultaneously. Heat energy can be extracted
from the earth in the winter and added to the building. In the summer,
the process can be reversed: unwanted heat is extracted from the
building and added to the earth.
The application of a geothermal system is a prime reason why the
Massry Center for the Arts is targeted to achieve a LEED (Leadership
in Energy and Environmental Design) “Gold” rating.
ADVANTAGES OF THE GEOTHERMAL HEAT PUMP
SYSTEM
Lower Cost: Can heat and
cool a building for 30% to 40% less cost. The system in the Massry
Center will pay for itself in as little as 3.3 years;
Low environmental impact:
The system will not directly use fossil fuels, thereby reducing
the amount of carbon dioxide released to the atmosphere. No natural
gas or fuel oil will be required. In addition, non-HFC (hydrofluorocarbon)
refrigerants will further reduce the building’s impact on
global warming gases;
Less Visible and Quieter:
Does not require an unsightly boiler stack or noisy cooling tower,
maintaining the character of the neighboring community;
No on-site combustion;
No exposed outdoor equipment.
SUMMER
In the summer, the earth acts as a cooling tower. The heat
pump loads the loop with heat, sending warmed water to be
cooled by the earth.
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WINTER
In the winter, the earth acts as the boiler. The heat pump extracts
heat from the loop, sending cooled water to be warmed by the
earth. |
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