The document provides an overview of geothermal concepts for ground cooling and tapping into the earth for home heating and cooling. It discusses how geothermal heat pumps use the earth as a heat source in winter and heat sink in summer. There are different types of geothermal systems - horizontal closed loops installed in trenches, vertical closed loops using drilled wells, pond/lake closed loops, and well open loops. While initial costs are higher, geothermal systems are more efficient and can save homeowners over $800 per year on energy bills, paying for themselves within 16 years. The document also discusses a case study of the TERI Retreat, which uses geothermal and other renewable energy sources.

1. AN OVERVIEW:
GEOTHERMAL CONCEPT OF
GROUND COOLING
FOR
TAPPING THE EARTH
FOR HOME HEATING AND COOLING
Presented by:
Ar. Tanuja bhandari-Trainee teacher
M.Arch (Architectural Pedagogy-final semester)
(UNDER THE GUIDANCE OF AR. AAMIR KHAN)

2. Ref- http://green.blogs.nytimes.com/2012/02/09/finding-energy-advantages-six-feet-under/
The word – Geothermal
comprises of -:
Geo (Greek word for earth)
Thermal (heat)
•Temperature Increases
with Depth

3. A geothermal heat pump uses the earth as a heat source when
operating in heating mode in the winter, and as a heat sink when
operating in cooling mode in the summer.
Working Principle
Ref- http://green.blogs.nytimes.com/2012/02/09/finding-energy-advantages-six-feet-under/

4. A Geothermal Heating/Cooling system is a more energy efficient alternative to
traditional central heating/air conditioning systems that utilizes the consistent
and stable heat energy available in either the ground or water to heat and
cool a home
All heating systems rely on three basic scientific principles.
1.) All matter contains heat.
2.) Cold is the absence of heat and exists only in terms of relation between the
differing amounts of heat contained in matter.
3.) Heat moves from higher temperature matter to matter of lower temperature by
means of conduction, convection, and radiation.
http://cas.illinoisstate.edu/sites/gmklass/?page_id=158

5. Engineers have been able to use these principles to develop “heat exchangers”
which can transfer or extract heat from one source and deliver it to another
Basic Geothermal Systems Take Advantage of:
Heat Differential Between Ground and Indoor Air Temperatures – Heat Pump
Earth as a Natural Heat Source – Power Plants
http://cas.illinoisstate.edu/sites/gmklass/?page_id=158

6. [vii][viii]
Horizontal Closed Loop System
This is the system which is generally
the most cost effective for installation
in homes.
The horizontal loop system requires
trenches at least 4 feet deep and two
feet wide to place the piping.
The length and number of trenches is
dependent on the size of the lot upon
which the home is to be built.
Certain techniques which are able to
loop the piping in each coil allow for
horizontal applications to be installed
on smaller lots.http://cas.illinoisstate.edu/sites/gmklass/?page_id=158
Types of Geothermal Systems[vi]

7. Vertical Closed Loop System
These systems are most commonly
used for larger commercial buildings
and schools.
This is due to the large amount of
land needed for a horizontal system
to provide enough energy to be cost
effective.
A vertical system functions the same
way as a horizontal. But instead of
being installed in shallow trenches
that run the length of the lot, the
loop is placed in holes drilled 20 feet
apart and 100-400 feet deep.
Types of Geothermal Systems[vi]….

8. Pond/Lake Closed Loop
System
For projects that are close to a
substantial body of water a
Pond/Lake system may be the
most cost effective.
In this type of system the closed
loop piping is run from the building
underground to the water source, at
least 8 feet below the surface to
avoid freezing.
These systems function just like a
ground loop system, except that it
draws its heat energy from water
and not earth.
Types of Geothermal Systems[vi]….

9. Well Open Loop System
This type of system is referred to
as “open” because it uses water
from a well or aboveground
source as the fluid used in heat
exchange that flows through the
heat pump system.
The water is then returned to the
source through the well, a
recharge well, or a surface
discharge.
Like the pond/lake system, this
system is only effective if there is
an adequate water source.
Types of Geothermal Systems[vi]….

10. A typical geothermal heat pump system costs about $2500 per ton of capacity, not
including drilling and installation. A typical residential unit will be a three ton capacity
system costing $7500.
Depending on the system, installation costs run from $10,000-$30,000. This translates
into the up-front cost in comparison to conventional systems to be from 50-150% more
expensive.[ix]
Energy Star certified geothermal systems all qualify for up to a 30% federal tax rebate
on all equipment and installation costs including labor.[x]
For a basic cost benefit analysis we will use $37,500 as the total cost of the system
and installation to reflect the highest cost for a typical residential system. Assuming the
system is Energy Star rated; it qualifies for the 30% tax rebate and runs at a minimum
of 45% more efficiently than a conventional system.
The tax rebate would bring the up-front cost of the system down to approximately
$26250. If we assume that this system is 100% (two times) more expensive than what
a conventional system would have been the initial investment for geothermal would be
$13,125 more.
Cost and Benefit of Geothermal

11. While 16 years is a long time for an investment to begin seeing positive gains, this
number assumes maximum system costs and minimal efficiency for an Energy Star
system. Obviously, a less expensive and more efficient system would pay for itself
more quickly.
There are also other factors which influence the cost-benefit analysis of a geothermal
system. Geothermal heat pump systems have better longevity and less required
maintenance than conventional systems.
They also add to the value to and reduce the carbon footprint of the home.
While the financial value of a geothermal system can certainly be measured in the
dollars and cents that a homeowner will save, what is perhaps its most important
benefit cannot.
The immediacy of the world’s environmental crisis must be taken into account in any
discussion of alternative and renewable energy sources.
Cost and Benefit of Geothermal…

12.  Geothermal energy is an important step in transforming our society in a
way that will help sustain life on our planet.
 cost benefit analysis we will use $37,500 as the total cost of the system
and installation to reflect the highest cost for a typical residential system.
Assuming the system is Energy Star rated; it qualifies for the 30% tax
rebate and runs at a minimum of 45% more efficiently than a conventional
system.
 The tax rebate would bring the up-front cost of the system down to
approximately $26250. If we assume that this system is 100% (two times)
more expensive than what a conventional system would have been the
initial investment for geothermal would be $13,125 more.
 At minimum efficiency for an Energy Star system (45%) on a home with
$1,800 yearly energy bills, the geothermal system would save $810/year. At
this rate it would take approximately 16 years for the system to pay off.
Cost and Benefit of Geothermal…

13. CASE STUDY: TERI-RETREAT
 Located on Faridabad - Gurgaon Road, Gual Pahari, Gurgaon
RETREAT (Resource Efficient TERI Retreat for Environmental
Awareness and Training) is TERI's vision of building a sustainable
habitat.

14. http://www.teriin.org/index.php?option=com_content&task=view&id
=32
 RETREAT is a part of TERI’s Gual Pahari campus, about 30 km south of Delhi, in
the northern state of Haryana. The beautifully landscaped 36-hectare site,
including a garden that features prize-winning roses, is living testimony to TERI’s
research. Nine years ago, the site was barren. Today, the site is transformed:
green, productive, and sustainable.
 Approach
 TERI’s Gual Pahari campus is intended to serve as a model sustainable habitat
based on new and clean technologies. Therefore, it makes full use of the most
abundant source of energy, the sun, by tapping its energy both directly and
indirectly.
 Some innovative ways of tapping solar energy and using energy more efficiently at
the RETREAT are as follows.
 Solar water heaters
Photovoltaic panels
Gasifier
Underground earth tunnels
Absorption chillers
Energy-efficient lighting
Waste-water recycling

15.  [i] http://www.usgbc.org/ShowFile.aspx?DocumentID=3638
 [ii] http://www.consumerenergycenter.org/home/heating_cooling/geothermal.html
 [iii] http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytop
ic=12640
 [iv] http://www.consumerenergycenter.org/home/heating_cooling/geothermal.html
 [v] http://www.energystar.gov/index.cfm?c=geo_heat.pr_crit_geo_heat_pumps
 [vi] http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/myto
pic=12650
 [vii] http://www.hannabery.com/source.shtml
 [viii] http://signaturesolar.com/?p=34
 [ix] http://www.consumerenergycenter.org/home/heating_cooling/geothermal.html
 [x] http://www.geothermalallianceofillinois.org/incentives/
 PAGES
 Energy & Atmosphere
 Energystar Appliances and Windows
 Geothermal Heating and Cooling
REFERENCES: