Geothermal Heating for the Tiny House

When choosing geothermal heating for your tiny dwelling, first cost and available space for the ground loop are the biggest concerns.

One of the concerns that I run into often is the upfront cost of installing a geothermal heating and cooling system.  Because of the economy of volume and size, it seems that the larger the home, the more reasonable the upfront costs are.  To put it more accurately, a larger heating and cooling bill may mean more dollars (in savings), so the numbers seem to add up more quickly. 

What if you’re in a tiny place with an already tiny energy bill?  What if you’ve got a well-insulated 280-sq. ft. home?  The website “HVAC OpCost” has a pretty good calculator to get a quick estimate of savings depending on efficiency.  I chose this one because it is not affiliated with any particular brand or type of equipment.  You just put in the facts and it will supply the estimated costs and savings.

Run the Numbers for Yourself

I put in the following data:  The home is in Chicago, and we’re comparing a gas furnace to a ground sourced heat pump with a Coefficient of Performance (COP) of 4.0 and an Energy Efficiency Ratio (EER) of 22, and it provided the following data:

The “results” page states that the home will save $1,331 in year one, and a cumulative $17,544 by year 10.  It also says that it increased the value of the home by $26,620.  But did you know that since geothermal heat pumps are “all-inside”, they often last two or three times as long as standard air conditioners and heat pumps? The 20 year column brings our energy savings up to almost $50,000.

The efficiency values that I input are not all that high for GSHP's (Ground Sourced Heat Pumps). Geothermal heat pumps are available in efficiencies of more than 40-EER and 5- COP, so the comparison is ramped down to a more average efficiency.

What Are the Extra Costs for Geothermal?

The extra costs associated with geothermal are in the ground coupling.  A geothermal heat pump system needs to have a ground loop or exchanger installed, which can cost several thousand dollars.  There are enough different types and cost variations that it is not prudent to guess.  However, the geothermal heat pump equipment costs are close to what you’d expect to pay for a high efficiency air-conditioner/furnace or heat pump system, so that amount is of less concern. 

Some Help With the Cost, and Some Extra Benefits

In addition, the federal government gives a 30% uncapped tax credit for geothermal heat pump installs that includes all the equipment and labor costs.  

Some of the other benefits that may make geothermal the choice for your tiny house include:

• Reduction in use of chemical refrigerants (geothermal usually has no refrigerant lines to the outside; just closed loop water pipes underground)
• Elimination of combustion related heating in the home (earth is the energy source; the sun replenishes warmth seasonally and continually, providing a truly renewable heating source). 
• Fundamentally, geothermal heating is no different than solar heating.  Earth is the great big solar collector, and we can tap into that heat all year long (with or without solar collectors).  A better answer!
• Some extras that enable the use of waste heat from the compressor for (DHW) Domestic Hot Water (instead of exhausting it to outside air in the summertime) further reducing environmental impacts relating to combustion or electric heating of domestic water.
• Reduced electrical consumption compared other heating and cooling systems (resulting in fewer emissions from power plants)
• Reduced Noise Pollution (from outside equipment cycling noises and distractions)

So if you’re considering heating and cooling a tiny house, you might be surprised at just how affordable geothermal can be!