Free, Renewable Energy From the Earth

Almost all buildings need heating and / or cooling to keep occupants comfortable. Office buildings, schools, homes, condos, churches, manufacturing plants, retail spaces... all need to be conditioned. Many need domestic hot water, refrigeration, process cooling, etc. Using the ground under and around the buildings allows you to reduce the amount of energy you need to purchase... reducing energy cost and impact on the environment.

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Weber State University Thermal Highway, Ogden, Utah

Central system that is using the chilled water distribution system for about 75% of the year. This project will phase out the chillers and boilers and be 100% convective circulation circuit by 2025.

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The GreyEdge Group, LLC

Company Profile

The GreyEdge Group specializes in architecture, engineering, and design of complex thermal energy systems using the Thermal Highway©. Successful systems are operating around the world delivering clean and comfortable heating and cooling on projects ranging from single-family homes to large district geothermal systems including a 123-story skyscraper.

The Group has evolved the breadth and scale of its water and geothermal energy services in innovative ways that deliver even more value to our customers. Using a unique Thermal Highway© concept, we now offer access to additional thermal energy sources including solar thermal heat, wastewater heat, industrial waste heat, thermal heat storage, and large scale recycling of thermal energy. Our solutions can scale up to large geographic areas by connecting integrated multi-source thermal districts. This powerful combination delivers system performance at much higher efficiency, with lower project cost, and lower operating cost than traditional unintegrated geothermal systems.

The GreyEdge Group, with eight specialty members, bring together unparalleled expertise with over 250 years of experience in all facets of the energy industry. Members have numerous patents and patents pending and are continually exploring new innovative concepts. Our multi-disciplinary team is adept at applying the best systems engineering and thermal energy engineering practices with an over-arching focus on emissions reduction. Our team uses a disciplined approach on projects that includes:

  • overall program planning
  • system emissions reduction
  • sustainable development operations
  • HVAC system design
  • multi-source and sink thermal energy
  • system performance optimization
  • system control optimization
  • best value design trade-offs
  • best technology assessment
  • technology upgrade planning
  • risk reduction management
  • system testing and methods
  • system technical training

Our Team

Unparalleled Complex System Experience

The members of the GreyEdge Group have all been committed to the ground source heat pump industry for many years. A combined total of over 250 years of experience in almost all facets of the industry around the world from projects ranging from single family homes to large district geothermal systems, give us unparalleled expertise in one of the most energy efficient heating and cooling technologies available.

The GreyEdge Team

Garen Ewbank B.S. I.E.&M, OSU, AEE Fellow
Matthew Garlick CCP, CxA, CEM, BEMP
Stephen Hamstra PE, AEE Fellow, ASHRAE HBDP, CGD, LEED AP
Duane Harman PE, MBA, CGD
Roshan Revankar PE, CGD, CGI, BESA


Successful projects around the world

GreyEdge members have been involved in geothermal heat pump projects around the world...North America, Asia, Australia and Europe. Projects ranging from single family homes, schools, recreation facilities, retail, offices, religious facilities...through to district geothermal energy utilities that move waste energy through a project rather than waste it.

Visit our Member Websites for More Projects


For more information email us here or use one of the methods below.


Paul Bony
The GreyEdge Group, LLC
12689 6100 Road
Montrose, CO 81493
Phone: 801-942-6100
Fax: 801-942-6127


Garen Ewbank
The GreyEdge Group, LLC
115 Woodcreek Drive
Fairview, OK 73737
Phone: 580-227-2358


William (Bill) O’Donnell
The GreyEdge Group, LLC
545 W. 19th
Idaho Falls, Idaho 83402
Phone: 208-523-8068


Gary Sexton
The GreyEdge Group, LLC
1870 Optimus River Road
Calico Rock, AR 72519
Phone: 870-297-8604


Stephen Hamstra
The GreyEdge Group, LLC
418 West Lawrence
Zeeland, MI 49464
Phone: 616-566-6185