Underground Micro Homes Part 2

Guest post by Walt Barrett

We have already established in a previous article for the tiny house blog that by building a home underground there are huge advantages when it comes to heating, and cooling. Starting from an average underground base temperature of 55° F it’s an easy jump to hold a small underground home to a temperature range of 65° to 75° Fahrenheit.

Now an underground home can be as simple as a pure survival model such as burying an old van, school bus, truck body or shipping container in the side of a hill or a hole in the ground with a combination stair well – light well, or it can be a well designed, and insulated modern home complete with all the necessary systems as a totally modern above ground home. One of the main differences is that the underground home design will certainly use far less energy, and it will be far less expensive to build if designed properly. If you miss the view of an above ground home, assuming there is a view to begin with, I suggest a TV wired to a web cam with a 360 degree sweep. Plus, you can always step outside to enjoy the view and contemplate the thousands of dollars that you are saving.

The Opal miners of Australia have been living underground for years. http://www.outback-australia-travel-secrets.com/coober-pedy-underground-homes.html Starting with crude carved out cave like homes they now have elaborate underground residences. We are not suggesting anyone carve out a cave, but underground living can be very economical. It’s much better if you can have either a light well, or dig into a hillside and have a south facing glass wall which can also serve as a solar wall. You can plant a vegetable garden on the roof, and by the way, the vegetables will grow faster from the heat below the ground warming the roots.

Today I would like to discuss some construction methods, and systems for inexpensive underground homes. Here is some construction information from the Internet. http://www.toolbase.org/Technology-Inventory/Foundations/wood-foundations And there is plenty more where that came from. The saving in concrete alone is considerable. Most of the actual building, and sealing of the “box” is just plain old common sense if you follow the insulating and sealing instructions on the foundation plans so that the water does not leak in. As far as basic construction goes, the link above should get you started in the right direction. I like the idea of using used shipping containers myself.

Today I want to discuss the systems that are common to all homes above, or below ground. The underground home systems will be less expensive though because less energy is required, so therefore less energy has to be collected.

The systems that you will need to consider include a LED, or a CFL lighting system. These can be done with either low voltage 12 volt direct current, or in the higher voltage 120 volts alternating current. These systems when powered by solar are now very simple and inexpensive. We are also currently experimenting with a three volt very low power lighting system. These new lighting systems do not require a large number of solar modules. Solar electric systems only get expensive when you start adding on high power (wattage) consumption appliances. Always remember that if you are off the power grid, and want to use 120 volts AC you will need an Inverter. An inverter is an electronic device that converts direct current into alternating current. For example, convert 12 volts DC to 120 Volts AC. Inverters do waste some power, as much as ten percent, but the 120 volt AC output is very convenient. There are two types of inverters on the market. The least expensive is what we call the modified sine wave, and certain equipment will not run properly on the modified sine wave units Then we have the more expensive full sine wave inverter, and all equipment runs perfect on it. I have been considering using surface mounted wiring systems. I think they are simplest to install, easier to inspect, and save a great deal of labor when finishing the interior. This is great for the DIY folks.

You will also need hot water for bathing, cleaning, and heating. You may want to tie in a very small fan coil through which you can circulate warm water if extra heat back up is needed for your space. This is just one method. The fan can be powered by 12 volts DC or 120 volts AC. We also use 12 volts DC to run well pumps, cattle watering tanks and small irrigated garden plots.

You are also going to need a refrigerator. Try to get by with the smallest, most efficient model possible so you will not be spending a fortune on extra storage batteries and extra solar modules. You may want to consider using a propane gas refrigerator, dryer, and backup water heater. Those items will cut down on the number of solar electric and hot water collectors you will have to purchase. It’s a great trade off.
Just remember that gas powered appliances must be well ventilated. Personally , I would design a special vent system for them.

Heating of course, is critical in cold climates. I’m just giving you an overview here. There are three ways, off hand, that I can think of, and they do not involve rocket science. Also remember that you will be picking up considerable “waste” heat from your cooking, appliances, lighting, and body heat.

The first method is solar hot water heat which can be the most expensive to install in a regular home, but not too bad in a micro home. It is also easy to store in the form of hot water. The next method is solar hot air collectors that are very simple to build. If you have solar hot air collectors you have another choice to make. You can use them to simply blow hot air into your home all day, and quit when the sun quits, or you can store the heat from the hot air system in a rock bin, or a similar device That becomes a heat sink or solar battery as some prefer to call it. The third method for heating with solar is the passive method which goes back thousands of years. Sometimes old technology is good! Passive solar is based on using the sunlight to heat a thermal mass directly. It works much better now with the invention of glass walls. The thermal mass can be barrels of water, rocks, concrete blocks, concrete walls, and concrete floors just to mention a few. This is best accomplished behind a double glass wall. These methods have been used in greenhouses for a very long time. You know how your car feels when you climb in even on a sunny, but very cold winter day. It’s passive solar heat. It’s a very simple concept.

I am also a very strong proponent of composting toilets and gray water systems. I can’t tell you how important this is. Every state that I know of is extremely concerned about both black and gray water disposal. I recommend using a well made composting toilet with ventilation out through a roof stack and a solar stack fan. The gray water including the separated urine should be filtered and channeled to the lawns, shrubs, and gardens. I am opposed to lawns myself, and do not have one. We use native plant gardens. Most of the waterways in the world have been ruined because of the polluted discharges from overtaxed sewerage treatment plants, and they are also a huge waste of money. We have much better ways to handle raw sewerage now, and composting is a major part of it. Many useful chemicals can be extracted from human waste and it was a common practice in Europe in past centuries. Yes, sometimes the old technology is better. It just doesn’t always make for good political pork barrel projects.

While we are on the subject of vent fans you must be sure to plan out a thorough ventilation system. This is an absolute must, or you will suck all of the oxygen out of the building and replace it with CO2 or worse. If you have combustible fuel heater you must have a CO detector an an air inlet for combustion air. It can be arranged so that a portion of, or all of the incoming fresh cold air passes over the heater. If you have a small wood stove you can run a 5 volt computer fan in a fresh air duct using a thermo electric generator that runs from heat on the side of the stove and in turn, runs the fan.

In summary, we have discussed some construction methods required to build an underground micro home, and many of the major systems required above or below ground. If you are unsure about how to wire, heat, cool, ventilate, or any other safety items always consult with others and get several opinions. Never be too proud to ask. That’s how I learned. I talk to many people during normal business hours, and try to share the knowledge that I have with them. You would be surprised at how much I learn from them too. My own personal goal is to see as many people in this world as possible be able to have decent place to live, and earn a decent living. The key word being earn! Your home doesn’t have to be a palace, and it doesn’t have to be a cramped tow person space capsule either. I would like to see all future homes fully off the power grid. It’s not that expensive, and it’s a matter of both security and economics. Please let me tell you that no child of the future should ever have to go through what many in our generation have had to bear regarding housing and cold weather. We owe it to all of them to leave the Planet a better place to live in than the way we found it, and also with a self sustaining economy. Not this train wreck economy we have now. It will be you, and not any government that accomplishes that goal – Trust me!

© 2010 Walt Barrett President A to Z Global Marketing Inc.
Contact Walt Barrett for permission to reprint.

11 thoughts on “Underground Micro Homes Part 2”

  1. Congratulations to you all, nice post, even most excellent, not to mention a multitude of problems can be solved. Only one question, and forgive me if it is not the appropriate place: “What is the average value for the construction of a building like that?

  2. We also have a house built halfly underground. Initially we planned to have a three floor house but the lack of money resulted that we finished just the basement. We use as a weekend house. Recently I figured out that the level of radon could be an important factor especially to control it because you can not feel this gas.

    For more information:

    To tell you the truth this seems to me a theoretic problem but it is important to know that you need good and often ventillation if you choose living in an underground house, because the radon concentration could be higher – as told you I think it is more a theoretic problem because you can avoid it by fresh air.

    So, this article was very useful and interesting I hope you will write more.

    Cheers from
    Europe, Hungary


  3. Have you tested for Radon in your underground home. Radon exposure is the 2nd leading cause of lung cancer in the USA. Hate to be a party pooper. Living underground has its dangers! Test, that’s the only way to know.

  4. Radon gas has been a problem in our area so we are quite familiar with the testing procedures etc. Installing an air quality system is a fairly simple procedure. The Internet is loaded with information. We test our basement periodically with kits purchased from the State EPA office. We have laws in RI mandating testing. Here is a summary of the various state laws. http://www.afhh.org/dah/dah_radon_docs/eli_database_radon_state_laws.pdf
    Now as to the question about actual costs, I will do some research and comment back on the topic. I can tell you right now that the figures will vary greatly because of different materials, construction methods, and if contractor built, or DIY owner built. I’ll do my best to find out.
    I would also like to respond to the comments on roof loading etc. When I wrote the piece, I was not thinking about going several feet under the earth. I was thinking more like twelve inches. I don’t want to get carried away, and have people living in a tomb either. A well designed underground home should include light wells and proper ventilation systems, or it is useless. I’m not sure I would not want to live in one myself, but when I write an article I do so to stimulate people into thinking about that particular subject. I believe I have succeeded in that aspect of the article. My interests in these homes are purely the energy saving aspects, and the lower construction costs. There are many plans around by the late Malcolm Wells that can be studied to gain more knowledge on the subject.
    http://www.malcolmwells.com/ It’s a very interesting web site.
    I will investigate more on the cost of underground homes.

  5. Another building type that hasn’t been discussed much in these forums is cordwood construction or hay bale construction. Both of these type structures can be build inexpensively and are solid alternatives to conventional stick build homes. Also, you can use rammed earth type structures through filling tires on one side with earth and build a retaining wall. One side of your home is underground and your wall of windows faces the south for the thermal benefits.

  6. Pile dirt onto a shipping container and it’s a short time until it collapses completely. Don’t believe me? Take a walk onto the tissue-paper-thin roof of a conex and then tell me you’d be willing to sit inside while a dump truck drops earth on top.

    If you’re going to build underground, talk to engineers or people who do it for a living, like the Utah storm shelter people. They use corrugated steel pipe which has great strength given the arch–some other companies like pre-cast concrete pipe (although that can lead to condensation problems).


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