What is Geothermal Heating and Cooling

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What is Geothermal Heating and Cooling?
By Clifton Greim, P.E.
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Common Options forEarth Coupling

• Closed Loop Applications
• Open Applications
• Standing Column Wells

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CLOSED LOOP Earth Coupling
Vertical closed loops
Horizontal closed loops
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OPEN LOOP Earth CouplingBest Efficiency Best
Performance

• 3 gpm / ton
• Responsible return to earth

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Standing Column WellEarth Coupling

• A Standing Column Well bridges the gap
• between the open well system and the
• closed loop system

EARTH COUPLING CHOICES Open Standing
Column Closed
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Economics

• Geothermal wells
• Vertical closed loop - 7,500/well
  
  (2,600-3,000/ton installed)
• Standing column - 80,000/well
  
  (2,400-2,800/ton installed)
• Potential Energy Savings
• Energy savings can vary depending on system
  types.
• Typical energy savings from a cost stand point
  can vary from .50/sq.-ft. to 1.00/sq.-ft.
  compared to a conventional ASHRAE 90.1 compliant
  system design.
• These savings assume the geothermal systems
  provide both heating and cooling to the building.

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Case Study Bowdoin College
Student Housing

• 66,000 square feet
• 180 beds
• Year-round occupancy / summer programs
• Heating / cooling required
• Limited capacity in existing underground steam
  line passing by site
• Campus beautification review committee distaste
  for pad mounted boxes
• Noise pollution concerns
• No storm water from site can impact towns
  over burdened storm utility

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Case Study Bowdoin College
Student Housing

• Base Case
• Gas fired boiler
• Air cooled chiller
• Fan coils (vertical) heating / cooling terminals
• Roof top ventilation unit (non-heat recovery)

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• Case Study
• Bowdoin College
  Student Housing
• Technology used
• Geothermal heating / cooling system
• 7 1,500 ft. deep standing column wells
• 5 30 ton heating / cooling water / water
  heat pumps
• 2 30 ton water / water domestic water heat
  pumps
• 2,500 gallon cistern collection system for
  green water for flushing fixtures

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• Case Study
• Bowdoin College Student
  Housing
• Additional technology used
• 2 air-to-air heat recovery ventilation units
• Infiltration beds for overburden of storm
• VFDs on the heating / cooling base mounted
  pumps and well pumps
• Occupancy controlled ventilation with VFD
  control on HRVU
• High efficiency condensing gas fired boiler
  for domestic hot water boost

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• Case Study
• Anticipated technology costs
• 7 1,500 ft. deep wells 455,000
• 7 30 ton heat pumps 160,000
• 2,500 gallon cistern collection system 55,000
• Heat recovery ventilation 25,000
• Credit for base equipment
• 150 ton air-cooled chiller 130,000
• 2 million BTU gas fired boiler 50,000
• Total premium for technology used 515,000

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Case Study Base case energy costs 150,000
/ year Anticipated energy savings 54,000 /
year Actual energy savings 82,000 /
year Anticipated pay back Actual payback
9.6 years 6.2 years Total KBTUs
60 less than base case
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Difference Actual/Model
Modeled
Actual
ASHRAE 90.1 Model (Base Case)
-228,287 kwh
738,136 kwh
509,849 kwh
Electrical
920,000 kwh
3,197 gals.
3,300 gals.
6,497 gals.
LP Gas
29,500 gals.
This represents an operational cost savings of
30 over model, 50 over base case
Total Energy Consumed (KBTU's)
Actual/Base
Modeled
Actual
ASHRAE 90.1 Base Case
Difference Actual/Model
-1,397,056
2,519,261
1,740,114
Electrical 3,137,200
-779,147
-2,107,075
303,070
595,125
LP Gas 2,702,200
292,055
-3,504,161
2,822,331
2,335,239
5,839,400
-487,092
Total Energy Consumption 17.5 lower than modeled
consumption 60 lower than base case
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• Lessons Learned
• - Full evaluation of sustainable options
• - First costs
• - Operational cost savings
• - Incentive availability
• - Test well for geothermal performance
• - Commission systems
• - Owner/facility buy-in to systems and
  
  commissioning
• - Involve all stakeholders
• - Staff
• - Administration
• - Students

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Thank you for your time!
QUESTIONS??
Clifton Greim, P.E. cgreim_at_harriman.com