Is Geothermal Heating and Cooling Right for You?

While geothermal heating and cooling is a proven technology used in millions of residences worldwide, there are several questions a homeowner should consider before investing in a system.   Articles on several reputable web sites point to some of the challenges facing the industry and the need for the homeowner to go beyond what is normally done for conventional HVAC systems.   However, because the potential benefits are so significant, and the tools exists for homeowners to protect their investment, there has not been a better time to consider the switch to geothermal heating and cooling.

1. Find an experienced installer.

The International Ground Source Heat Pump Association (IGSHPA) has accreditation programs for both Installers and Drillers.   Look for an installer who is accredited, has experience in your area, and is willing to stand behind their installation.    International Ground Source Heat Pump Association (IGSHPA) has accreditation programs for both Installers and Drillers.   Be sure your installer and driller have gone through the proper training and check references.

2. Know your building load.

If you are in a northern climate, you will likely be heating dominated and want to design to meet your maximum heating needs.   For southern locations, you will want to focus on your cooling load.   The International Ground Source Heat Pump Association recommends that because the geothermal system is using your ground as the primary heating source (or sink), it is important that the system is properly sized.

Have your HVAC contractor conduct a “Manual J” analysis to determine your building load and consult with a building energy analyst to explore strategies for reducing your load.   Reducing your load by one ton of capacity can save thousands of dollars up front and provide additional savings in the future.   You can read more about the Manual J analysis in this article on the Residential Energy Services Network (RESNET) website.

When it comes to properly sizing a geothermal system, more is not necessarily better.  As noted in this article, oversizing the system results in both higher installation costs and a poorly performing system.

3. Be realistic about projected cost savings.

Geothermal heat pump systems offer the potential to significantly reduce energy heating and cooling costs and reduce greenhouse gas emissions.   GSHP system performance is often described by  a ‘coefficient of performance’ or COP that is the ratio of thermal energy produced to electrical energy consumed.    While the COPs of the heat pump equipment are certified in the lab according to industry standards, actual performance may vary and depends on details specific to the installation (e.g. power required to circulate the fluid through the ground loop, actual entering water temperatures over the course of a season, and the efficiency of the HVAC distribution system).
Energy Cost vs. Coefficient of Performance
As shown in the figure to the right, once the installed COP exceeds approximately 3.5, most of the savings have been achieved and the costs savings associated with increasing the COP from 4 to 5 can be on the order of a few dollars per million BTUs (MMBTU).

Ask your installer what you can expect in terms of actual COP and what measures they take to ensure a high performing system.

4. Protect your investment.

A GSHP system consists of four interrelated elements, all of which must be designed to work together.   The building load is in response to the outdoor weather conditions and depends on the types of building materials used, the building load is met through an HVAC distribution system (usually forced hot air or radiant hydronic).   The distribution system is tied to a geothermal heat pump whose performance depends on both the ground loop temperature and the efficiency of the HVAC distribution system.   The ground loop extracts heat from the ground and its performance is based on the ground characteristics and the rate of heat being extracted.     When each component is properly sized and operates as designed, a GSHP systems offers unsurpassed performance.    However, if one component is not designed properly or is experiencing mechanical problems, it can affect the performance of the entire system.

Ground Energy Support offers a variety of monitoring options that can enable the homeowner to assess each component of a GSHP system  and identify issues that may be adversely affecting overall system performance.    Most often, these issues are minor and be easily addressed through routine system adjustments.    However, if allow to persist undetected, they can inhibit the system from operating at its full potential and could lead to unnecessary wear and tear of the equipment.

 


Recent GES Articles

 

Geothermal RECs in NH — 2014 RECs SOLD!

Matt Davis  -  Jun 20, 2015  -  1 Comments
Another milestone reached After more than three years since the passage NH SB-218, another major milestone has been reached. This week, Revolution Energy and Knollwood Energy teame...

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New Hampshire Recognizes Geothermal Heat Pump System as a Renewable Energy Facility

Matt Davis  -  Dec 10, 2014  -  No Comments
Today, the New Hampshire Public Utilities Commission approved Rolling Dog Farm as a Class 1 Thermal Renewable Energy Source, the first geothermal system to be recognized under the ...

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NH Thermal RECs: What you need to know

Matt Davis  -  Jul 17, 2014  -  4 Comments
Thermal Renewable Energy Certificates (RECs) in New Hampshire In 2012, the New Hampshire Legislature passed SB218 that formally incorporated ‘useful thermal energy generated ...

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Performance Monitoring – COPs

Matt Davis  -  Jun 13, 2013  -  , , ,  -  Comments Off on Performance Monitoring – COPs
Introduction This article is the second in a three-part series prepared by Ground Energy Support LLC (GES) that will highlight some of the lessons learned from over 100,000 hours o...

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Performance Monitoring – Ground Loop

Matt Davis  -  Jun 01, 2013  -  , , ,  -  Comments Off on Performance Monitoring – Ground Loop
This article is the first in a 3-part series prepared by Ground Energy Support LLC (GES) that will highlight some of the lessons learned from over 100,000 hours of GSHP real-time m...

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Performance Monitoring Series

Matt Davis  -  May 25, 2013  -  , , ,  -  Comments Off on Performance Monitoring Series
In Spring 2013, we began publishing a series of articles on Performance Monitoring that highlight the lessons learned from over 100,000 hours of geothermal heat pump system monitor...

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Measurements Confirm GSHP Cost Savings

Matt Davis  -  Jul 10, 2012  -  Comments Off on Measurements Confirm GSHP Cost Savings
One unique capability of the GxTracker™ is to accurately document both the energy produced by a GSHP system as well as the energy consumed.   Combining this system-level perfor...

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Geothermal as a Renewable Energy

Matt Davis  -  Jul 02, 2012  -  , , ,  -  Comments Off on Geothermal as a Renewable Energy
Recent Maryland legislation formally recognizing geothermal heating and cooling (GHC) system as a renewable energy resource has great potential for increasing the adoption of groun...

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    • Your system has been absolutely crucial in helping me monitor problems as they occur, right at my fingertips. Doing without it would be like driving a car without any gauges. - Pete W., Homeowner
    • It is interesting to follow the data and understand what the system is doing. …Love this information, wish I had known about it before – I am really glad I installed it. – Steve H., Homeowner
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    • I did not know that my oil heat circulator was cycling on every 6 hrs until this monitoring showed me that. Why add heat 4 times a day in summer?! I turned it off after GES alerted me to what was happening.” Pete Tavino, P.E., IGSHPA Instructor
    • I have been checking the GxTracker, and noticed that the total heat rejected was less than it should be. I checked it out and the machine was a little low on refrigerant so I recharged it. I checked the website and system efficiency improved by almost 40%, cool! -- John S., Geothermal Professional
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