Basics of Ground Source Heat Pump Technology (Part 2)

In last week’s post, I gave you some things to think about regarding ground source heat pump (GSHP) or geothermal heat pump (GHP) technology design. GSHP technology takes advantage of the fact that the ground temperature stays relatively consistent throughout the year, and uses electrically powered systems to transfer energy to and from the ground. During the winter GSHP systems use the ground as a heat source, and during the summer they use the ground as a heat sink.

In this post I’m covering some topics on economics and project implementation. GSHP technology can be quite the expense, but picking the right designers/contractors to be on your team can vastly simplify the process and help manage costs.

Economics

When we conduct a feasibility study to determine if a GSHP system is economical relative to the capital investment, we look at a lot of different factors.  Here are a few of them:

  1. Your existing energy rates.  This works to your advantage if your electricity costs are relatively low, and your fuel costs are relatively high. With a GSHP system, you are going to be using less fuel for heating, but your overall electricity consumption will probably go up. Depending on what you pay for your energy now, this could save you a considerable amount on your annual energy costs.
  2. If your existing heating or cooling system is in need of replacement (soon).  When you consider the incremental cost of putting in a GSHP system vs. a standard heating/cooling system, the energy savings may just make the project worth it.
  3. Whether you have a sufficiently open area to accommodate a loop field near your building of interest. GSHP loop fields take up their fair share of space. You can install loop fields under parking lots, but then you have the added expense of repaving the area.  You can also install a loop field a reasonable distance away from your building of interest, but then your costs for interconnection piping go up. Keep in mind the placement of your existing utility lines—the last thing you want to do it mess with buried electrical, natural gas, or steam lines! Moving things around to accommodate a loop field will quickly add on to your capital costs
  4. If there are local, state, or even national incentives that might lower capital costs. For example, the New York State Energy Research and Development Authority (NYSERDA) currently offers incentives for ground source heat pump projects. Federal tax credits may also provide a project with an economic boost. Check out the DSIRE website for a complete listing of incentives in your area.

GSHP Designers and contractors

Experience matters in most things including brain surgery and GSHP design and installation. Here are some things to consider when making the important selection of designer/installer:

  1. Avoid having a project developer do your feasibility study.  Get a third party if you can.  This goes for any kind of project – be it a new GSHP, a compressor replacement, or a CHP system. Though most GSHP designers and contractors are upstanding experts, there’s an inherent conflict of interest when the developer trying to sell you a project is also the person investigating whether it’s beneficial to you. We strongly recommend that you do what you can to separate the decision of whether a system is right for you from the design/construction process. At the very least, two sets of experts are better than one at catching mistakes and potential pitfalls.
  2. Make sure that your designer/contractor has experience with the type of system that you want. If you’re looking at a commercial GSHP system, then make sure that your designer/contract has sufficient experience with installing large commercial systems. The same thing goes for residential systems.  Similarly, there are many different types of GSHP loops (i.e., open loop vs. closed loop, vertical boreholes vs. horizontal boreholes), and the same experience statement applies here too.
  3. Check for IGSHPA designer and installer accreditation. The International Ground Source Heat Pump Association (IGSHPA) is the place for GSHP training and accreditation. You can search their database for accredited designers and installers in your area on their website here.

Depending on how big the project is, you may also want an owner’s engineer to help manage the project. Owner’s engineers work for the you—the customer—to make sure that the project stays on schedule and help catch any issues with the design/permitting/implementation process early on in the project so that they don’t turn into costly issues later on. 

ANTARES has significant past experience working with customers on project implementation, and may be able to help you with all of these important decision-making processes. Since we don’t have any affiliations with designers or installers, our analyses are always our own and not skewed towards outside interests. If your Dentist tells you that he is behind on his Bugatti Veyron payments and that you have 8 new cavities all in the same breath, a third party opinion may be worthwhile.

Give us a call if you’re considering a GSHP. Whether you’re just starting the think about a system or you have a detailed design on your desk, we can help.

About Sara Aaserud


Sara works as a Renewable Energy Engineer in ANTARES’ Fayetteville, NY office. Her favorite types of projects are solar PV feasibility studies and electricity rate tariff analyses. She can be reached at saaserud@antaresgroupinc.com.

Comments

  1. Hi Sara,
    I am a home builder in central Texas and would like to build zero energy homes. I was planning to use a chiller with a combined heat and power unit (fueled by natural gasl). The CHP will have extra available heat, especially in the summer. Would a chiller be a good choice for this situation? I am trying to offer homes at a very competitive price and I am trying to make the very best choices for all the products I will use (durability, efficiency, price, low maintenance).
    Thank you, Joe

  2. Hi Sara,

    I kept reading and I think I have the answer I asked you, in an earlier text.
    If you have any suggestions regarding this: I want to build zero energy homes here in central Texas. I think the CHP’s (fueled by natural gas) looks like the best choice and then to use things that will work well with that product (ie. chillers). I would love to hear your take on all this and any suggestions that you might have. Thank you, Joe Schultz

    • Sara Aaserud says:

      Hi Joe! I’ve personally never heard of a CHP system being used in a personal residence, but it could be done. What type of CHP prime mover would you use? You will need to look at maintenance costs for those systems. I imagine that they would be harder to fix/replace than typical furnace/AC systems (a typical residential HVAC tech may not be able to handle them), and that the CHP aspect may scare some people off. Cost-wise, I imagine that a CHP system would be more expensive for you to purchase and install than an energy star rated gas furnace and electric AC.

      I did a post on absorption chillers here: http://antaresgroupinc.com/how-to-decide-if-an-absorption-chiller-right-for-you/ In my personal opinion, absorption chillers are complicated and should not be used unless you are willing to undertake their special qualities. I’ve seen industrial/commercial facilities (that have dedicated maintenance staff!) with absorption chillers installed, and they just can’t get them to operate correctly.

      This particular blog post that you commented was on ground-source heat pumps (GSHP). That could be an efficient option where you live, however, those systems are something that would need to be installed by a qualified installer, which may increase your initial cost. Improperly designed GSHP systems can work fine for a few years, but start to go bad over time and not work as effectively.

      Lots of stuff to think about! Good luck!
      -Sara

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