A discussion about geo thermal

Geo Thermal has been in the building industry long enough  for there to be solid results on how these heating and cooling systems are working in ultra energy efficient homes. We have multiple houses that use geo thermal systems for heating and cooling just as we have multiple houses that use conventional and hybrid heating and cooling systems. Because of an increased interest in geo thermal systems lately, I thought that I would put my thoughts together and let everyone have access to them.

In the past, I would always be against geo thermal systems in the houses that I designed and built because of how little those systems would run in the types of homes that we were building. Another reason that I would be against the geo thermal systems is because our HVAC subcontractors would always say, "What do you want to use for the supplement heat?". I have a problem with that. Apparently, the geo thermal systems that our 'subs' were installing around the state would not work below about 28 degrees Fahrenheit, well, let me rephrase that, the systems would switch functions at about 28 degrees. Inside of geo thermal units, there are electric elements that will heat the air or liquid depending on what type of heating system the house has (forced air/radiant heat?). That is why the 'subs' would ask what supplemental heat source we wanted, because using the 'onboard' electrical elements in geo units gets very pricey. One of our past homeowners who has geo thermal in his house told me that he had an $1,800 electric bill during a cold month a winter ago because his geo thermal unit heated his house with the onboard electrical element.

So why is there still so much hype over geo thermal? In my opinion, because it is a cozy blanket/warm feeling for people buying a house in a time when energy prices are unstable. A recent conversation that I had with a potential client opened my eyes to the opinion I just gave. The potential client ask another builder about building an energy efficient home and the builder said, "Well, we put geo thermal in all of our houses." The builder became confused when asked further about what made the house energy efficient. Putting geo thermal in a conventional 'production builder' house may make sense, because a propane fired furnace would cost a fortune to run in a house like that. I don't know enough about the house in question to form any other opinions. The point is, a 'hot button' is not always the best fit even though everyone is always mentioning it.

I will go on record as saying that geo thermal has its place in the building industry and may or may not be the best fit for any particular project. As I said to someone recently, .."the answer to the question of if geo thermal is the best fit for your project is like a law question, it depends." Science is what dictates what is used in house. As I mention in my book 'Build Green, Make Green, Save Green', I feel that Newton's Third Law of Motion (..This means that for every force there is a reaction force that is equal in size, but opposite in direction. That is to say that whenever an object pushes another object it gets pushed back in the opposite direction equally hard. )(Rice University) can be applied in its own way to a house. Meaning, that whomever is building the house must remember that for everything they do to a house, whether it is insulation or installing a wood burner, that something else will occur as a result of that installation. Mold and mildew is an example of this point, so is indoor air quality. Another example is something I hadn't considered a while back. A person I knew well told me that his father built an Insulated Concrete Form (ICF) house a while back and that he wanted to pick my brain. I said "OK", and he started to tell me that his father's house had a weird, almost 'septic' smell to his house. I asked if there was an air exchanger in the house and this guy said, "No, he just opens the windows a little bit to get the house to breath." Would anyone ever think that make up air could come through plumbing vents? That is what was causing the 'septic smell' in his father's house. Equal and opposite force. Also, opening windows in the winter to get the house to 'breath' kind of defeats the purpose of having such a tight exterior envelope if you ask me!

When I am designing a house and getting ready to estimate the cost of the house, I always have multiple heating systems figured for that house. By doing this, we can see which system will be the best pay back for the house. We have houses that are Platinum Certified LEED for Homes houses that have natural gas fired boilers, propane fired boilers or natural gas fired forced air furnaces. We also have used propane fired forced air furnaces in several of our houses because we have found that those heating systems don't run very hard in the homes that we build and don't cost very much to run. 

I am certainly not bashing geo thermal companies or people that want or have these heating and cooling systems. I am simply giving my input based on multiple case studies of houses that we have built. Whenever I hear or see an email of someone asking about geo thermal, my first response is in the form of a question, "Tell me why you are thinking about using geo thermal". Sometimes people get defensive, so I will follow up my question saying something like, "there is no right or wrong answer, I am just trying to understand more about what you want and need." Recently, I met with a potential client who mentioned geo thermal and she answered my question about geo thermal in her own way. I asked her a follow up question that sounded something like, "what do you heat with now, what does your current house use as a heating source?" Her reply was, "this house is all electric, but we always heat with wood, using the wood burner downstairs.." Again, another follow up question, "Do you want a wood burner in your new house?" To which, she replied, "definitely". Had she replied, "No, burning wood is too much work for us..", then I would have asked further questions about what fuel sources were available and geo thermal to see if the system may be a good fit for them. Instead, knowing that they want to heat with wood means that the heating system that we would install in their new house would basically be supplemental heat until such time as they no longer wished to heat with wood, which could be 20 or more years into the future.

Are you tracking so far? Good. My point in all of this, is that there is much discussion and 'scientific-ness' that goes into selecting the parts of a house, heating and cooling systems included. That is why I always called our houses 'Hybrid Homes', because of the origin of the word hybrid. Latin for hybrid is mulus which translate to mule. A mule is the first hybrid in recorded history and dates back to the ancient Romans who combine a donkey and a horse. This combination of a donkey and a horse had to be very specific or else the offspring would not be a mule nor be able to function as a mule, which was the reason the ancient Romans would go through all the trouble of tracking down these specific animals. For the record, the correct combination for creating a mule is a male donkey and a female horse.

As you can see, you can still combine components to create something else, but in order to have the outcome turn out as the designer or builder intended, the combination of components has to be correct to not create an unfavorable result. This is normally the case in the building industry and thankfully more builders are catching on and understanding the importance of what goes in to a house.

In closing, I will continue to say that geo thermal has its place in building. In fact, if anyone reading this can explain geo thermal better, than please do in the comment section. I want to learn more about why people are so interested in geo thermal if the system is so limited.

Thank you for reading, stay tuned for more entries coming soon..

AB