Design Considerations with Geothermal Heat Pumps (GHP)

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Design Considerations with Geothermal Heat Pumps
(GHP)

• Introduction
• The Big Picture
• Background - Commercial Mechanical Systems
• Benefits of employing GHP in a building project
• THE GROUND EXCHANGE (GX) types and factors
• The Future of GHP
• Questions

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Design Considerations with Geothermal Heat Pumps
(GHP)

• The Big Picture
• GHPs are not new technology, proven
• GHPs are EQUIPMENT, the GX is ENERGY
• GHP equipment can be employed in most any system
  that currently exists it merely makes use of a
  different energy source
• Large scale deployment WILL reduce energy
  consumption.40-50 of increased electrical
  demand
• Discussion needs to center around the energy side
  - the GROUND EXCHANGE

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Design Considerations with Geothermal Heat Pumps
(GHP)

• Fundamentals of Building Mechanical Systems
• System Architecture Centralized or
  Decentralized
• Delivery of Energy Direct or Indirect
• Energy Transfer Air or Radiant
• Energy Source Electricity, Gas, Propane, Fuel
  oil, etc
• Geothermal ground exchange systems
• All of the above types of architecture, as well
  as delivery and transfer of energy can be
  employed by using GX as an energy source.

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Design Considerations with Geothermal Heat Pumps
(GHP)
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Design Considerations with Geothermal Heat Pumps
(GHP)
Coil
Central Boiler
Air Handler
DIRECT HEATING
IN-DIRECT HEATING
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Design Considerations with Geothermal Heat Pumps
(GHP)
Regardless of the system architecture, how the
energy is delivered, or how the energy is
transferred to the space, the ground exchange
(GX) is a viable ENERGY SOURCE for a variety of
systems.
Sources of ENERGY
Combustion of Fossil Fuel
Electricity
Energy Exchange e.g. Geothermal
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Design Considerations with Geothermal Heat Pumps
(GHP)

• Benefits of a Geothermal System for Owners
• Zoning flexibility
• Simplified Controls
• Ability to heat and cool from a single unit
• Ability to heat and cool different parts of the
  building at the same time
• No visible exterior equipment
• Typically less mechanical space required and
  fewer building penetrations
• LOWER ENERGY COSTS

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Design Considerations with Geothermal Heat Pumps
(GHP)

• GX Horizontal Loop Considerations
• Fairly inexpensive for small loads (residential)
• Takes up large ground area, virtually impossible
  for larger installations
• Not as efficient (ground temperatures vary at 7
  feet)
• Variable exchange rates with different soils
• Disruptive to site, very expensive if backfilling
  is structured
• Really only viable for smaller installations with
  open ground available proper design imperative

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Design Considerations with Geothermal Heat Pumps
(GHP)

• GX Vertical Loop Considerations
• Requires less ground, but still must have
  available site space for fairly large bore field
  for larger installations
• Expensive, especially without qualified drillers
• More efficient with more stable temperatures
• Variable exchange rates with different soils
• Disruptive to site, needs manifolding of
  vertical loops
• Good option where groundwater is deep, poor
  quality, or unavailable
• Proper design imperative

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Design Considerations with Geothermal Heat Pumps
(GHP)

• GX Ground Water Sourced Considerations
• Requires virtually no ground can be installed
  in urban environments
• Usually the least expensive, per ton, if
  sufficient water is available (Applicable to many
  areas in Montana)
• Most efficient with very stable temperatures
• Can be used with open or closed loop systems
• Need to watch water quality and depth to aquifer
• Does not use water, just borrows it.
• Does not require specialty installation for the
  GX needs proper design, however.

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Design Considerations with Geothermal Heat Pumps
(GHP)
Case Example Lincoln County Credit Union,
Libby, MT

• Open Loop GX
• Closed internal loop
• Includes Air system in office space
• Radiant floor lobby heat
• Energy Recovery Ventilation
• Highly zoned space
• Simple controls

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Design Considerations with Geothermal Heat Pumps
(GHP)

• Future of GHP
• Its about the energy, the GX, the single largest
  factor that makes GHP non-competitive
• Utility type infrastructure? (USDA/RUS Loans)
• With more education, lowered misunderstandings
  and misapplication of GHPs
• Higher usage will lower unit cost and increase
  efficiencies
• Will be instrumental in lowering future demand
  for electricity should it get benefits of
  renewable power
• Lower hurdles, particularly for well drilling and
  permitting

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Design Considerations with Geothermal Heat Pumps
(GHP)
QUESTIONS? Contact Shane Jackola, PE, LEED
AP Jackola Engineering and Architecture, PC 2250
Hw 93 South Kalispell, MT 406.755.3208 shane_at_jack
ola.com