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Energy Efficiency: The Ideal Off Grid Home

Discussion in 'Off Grid Living' started by fireplaceguy, Nov 18, 2010.

  1. fireplaceguy

    fireplaceguy Monkey+

    (Title should read "home" dangit!)

    In the PV solar world there's an old axiom that for every dollar you spend on efficiency you save two dollars on your solar system. With PV module prices where they are, that may no longer be true, but efficiency still matters.

    Let's war game the design of an ideal off-grid home, starting with the structure itself and then looking at cooking, heating, all the appliances and finally the energy systems themselves and see what we can come up with. I'm basing this on what I know today, and I already have a fairly complete design in mind, but I'm always looking for better ideas, so please jump in!

    I'll kick things off with the structure I plan to build next spring. It's earth sheltered and extraordinarily strong. (So strong that you just drive the bulldozer up on top of it when you're burying it with dirt!) Built the way I plan, it's fireproof (including forest fires), bulletproof, blast proof (besides the glazing), windproof (including hurricanes and tornadoes), earthquake proof and highly secure. This structure requires little to no exterior maintenance, and the interior temperature will hover in the mid 50's year 'round with no heating or cooling inputs at all. (With two people living there, bathing, cooking and lighting heat inputs alone will raise the temp to around 60.)

    Here's the site for the structure: Formworks
  2. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Level ground or hillside? Oriented how? Passive heat pipe system? (You will not like indoor temps of 50 or 60.)
  3. fireplaceguy

    fireplaceguy Monkey+

    Level ground. The dirt it's buried under will have to be excavated and/or hauled in. The land has a year-round spring that flows about 6 gpm, and I plan to get a lot of the dirt by excavating a large pond. For security reasons, I'd like to bury the house deeper than actually necessary for thermal purposes, so I'm hoping to get some fill hauled in cheaply. I'll use the topsoil from the pond to finish it off, because I intend to terrace the entire roof for vegetable gardens.

    Even up in Canada an unoccupied home like this never drops to 50 degrees. An occupied home will stay around 60. I have no intention of living with temps around 60, but a small wood stove and a cord of hardwood a year would be all I'd need to bump that up to a comfortable range. I really like a wood fire anyway. It might be a little cool in the summer too, but opening a couple of windows now and then would take care of that.

    I'm seriously considering casting hydronic heat lines into the floor in at least the key areas if not everywhere, and eventually using solar collectors for heat. My domestic hot water will be solar anyway, so it just means an expansion of that system. That wouldn't be viable in a conventionally built home, but you don't need many BTU's per square foot to achieve comfort when the temp just outside your walls never drops below 55 degrees. That puts it well within the capacity of a modest evacuated tube collector setup.
  4. fireplaceguy

    fireplaceguy Monkey+

    Thanks, RightHand - yu kin jsut foloww me aorund an spel fr me anietiem yu wnat!
  5. BadgeBunny

    BadgeBunny Monkey+

    Boy ain't that the truth ... I tried a little experiment when the weather cooled off here. Turned the heater down to 60 and decided that no matter what I wouldn't turn it up ... wear more clothes, fire in the fireplace, drink coffee ... whatever, but no turning the heater up.

    I dunno how much longer I am gonna last ... our first 20 something degree night is coming up ... I may be on the floor cuddled up with the dog before it is done.

    We have considered an underground home but those we know here in our area who have them apparently have nothing but trouble. Water table is too high. I don't even know a single person who has a basement or storm cellar who doesn't have problems.

    Thanks for the info fireplaceguy ...
  6. fireplaceguy

    fireplaceguy Monkey+

    Hey, BadgeBunny! Many earth sheltered home companies do very primitive waterproofing - they spray something on or use tar. All such sealants will eventually leak with an earth sheltered roof, and digging one of these up would be a real pain because it's thinwall concrete and easily damaged by earth moving equipment.

    Formworks uses a bentonite clay impregnated waterproofing that comes in long rolls. You can see it in some of the pics on their website. The moment bentonite gets wet, it expands and seals. Period.

    They furnish the waterproofing materials as part of the kit, and I talked to a big commercial waterproofing contractor up in Denver to confirm what they say. He was very impressed with the whole idea, and agreed that the way they waterproof these structures would actually work. He's actually dug up a two earth sheltered homes around here, and that's exactly what he used to stop those leaks.

    BTW, the Formworks guys have built a number of these near you (tornado country - big motivator!) and have had no problems with water in any of them. Of course, water tables are another matter. You have to build above the water table, unless you're Noah.
  7. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Or provide drainage around the footers, a sump and pump, as well as make sure there is enough weight (lightweight structure?) to prevent it from floating. +1 on bentonite, if it's installed correctly.
  8. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Hey Fireplace guy, look this up on u-tube and see what you think. cansolar.com
  9. Witch Doctor 01

    Witch Doctor 01 Mojo Maker

    I have a friend (former POW) who built a double walled concrete block structure (1979) with reinforced concrete roof and back filled over it block walls had a 3ft dead space that he filled with packed earth visited him when it was wind chills of -20 all he did was crack open the dampers and heated the structure ASAP... house was around 1800 sq feet with solar, wind and a water generator... nice cozy place for a single guy... not as nice as these but low-tech and usable.. not sure about any of the construction specifics but an interesting concept.... I wanted to try to build one but the wife is a little clastrophoebic so thats out....
  10. curtis596

    curtis596 Monkey+

    I love earth sheltered or earth bermed homes. I also plan to build on in the future. A while back I started a blog to keep track of all the builds I was following online. You might want to take a look. There is a build that is from Formworks but there are others, too. Earth Sheltered
  11. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Fireplaceguy, if you would loan me the money, I will build one and then test it out for you for a few years and let you know how it goes. LOL I love it and have watched quite a few shows over the years on building this type of Home. I got interested in them when I could actually afford a "geodesic" type home. I soon found out that getting banks and building dept.s interested in them was a real nightmare at best. Finally gave up on the idea. But if you have found a way around those obstacales, then go for it. Maybe when you get it done, I will come vist you up there, especially if there is good fishing close by. Not sure if you have looked up the cansolar heat I mentioned above, but I really find it very interesting and workable. But I could build my own using either copper or alum. pipe rather then beer cans. Especially since I don't drink.
  12. BTPost

    BTPost Old Fart Snow Monkey Moderator

    If hydronic heating is in your future, just make sure you insulate the Slab from the ground, or you will lose most of your heat into the ground. I have designed systems that use such a Slab Heat-Sink as the Primary Cooling System for the sites 3Kw Water Cooled Diesel Genset. When you pay for those BTU's in the purchase price of the fuel, it seems very dumb to throw them away heating the Great Outdoors.
  13. Maxflax

    Maxflax Lightning in a bottle

    This is one of the possibilities for our castle construction

    PNW Pacific Northwest Insulating Concrete Forms FORMTECH

    These designs include footers that have built in drainage systems, The location is a ridge top and had good drainage, but it is Western WA State and in a rainforest. The R value should be close to 50 and like Fireplaceguy I expect to use less than 1.5 cords of wood per year to heat about 3,000 sq feet + basement/garage bay (which will be in the full basement)

    It will have all of Fireplaceguy's advantages plus smooth vertical walls @ minimum of 26 feet height. I have plans to further secure the home with a 12 foot perimiter curtain wall (very Norman 12th century) and other features I will keep to myself

    In addition to the basement log burner we'll have a kitchen stove with propane/wood capability and one the 2nd floor near the bedrooms we'll have a South facing bay with a small wood stove for auxiliary heat
  14. Maxflax

    Maxflax Lightning in a bottle

    We own the land outright and we will be building with cash so to hell with the banksters [reddevil]

    The design, being somewhat conventional except for the ICF aspect should sail right through, as long as they don't demur about the weight, up near a ridgeline. The entire hill is heavily forested and the home will be back at least 100 feet from the true edge, so I hope it will fly
  15. Maxflax

    Maxflax Lightning in a bottle

    It says 100 years on the earth sheltered site..if built correctly and maintained these homes should last 500 + years! Many Norman castles are still standing, 800 years later
  16. Clyde

    Clyde Jet Set Tourer Administrator Founding Member

  17. fireplaceguy

    fireplaceguy Monkey+

    That Ultimate Secure Home website is down and for sale, but the home (which has sold) is here in Colorado. I considered going to look at it when it first came on the market, but they were asking way too much and I was already familiar with all the bits and pieces they had used to build it.

    After much research, I consider Formworks to be the best technology for an earth sheltered structure. For everyone's information, Formworks and Performance Building Systems are owned by two brothers. The PBS brother left the company years ago to make his fortune in real estate.

    The PBS brother is back now that real estate is dead, but he was not involved in the business when the refinements were made, so he only has rights to the original patent. That original process, still in use by PBS, does a marginal job of encapsulating the innermost layer of re-bar with shotcrete. It might be difficult for those original structures to pass inspection these days, if inspectors just had a clue what they were looking at. Too bad, because he's a real patriotic conservative, a serious shooter and a very nice guy. Also, PBS still leaves customers on their own for waterproofing, which could come back to bite people who haven't done enough research and try to skimp on this step.

    Dale over at Formworks stayed in the business straight through, and has refined and perfected the building system along the way. All his subsequent refinements add much to the strength and durability of the structure. Also, Dale tells me he has never had a residential project that was denied construction financing or a mortgage, including FHA money. I will build with cash, living on site in my school bus (with my wood stove, PV solar and my Sun Frost fridge!) while I build. I also intend to be fully off grid from day one, so the fewer people who know what I built, the better.

    Back to why I started this thread, this structure is the result of a lot of research into four criteria: 1) Best safety/security, 2) lowest ongoing maintenance costs, 3) lowest heating/cooling energy input over time, and 4) reasonable construction costs. (And lemme tell 'ya - I'm a little stunned to have met all four criteria at all! The cost of any other stout structure is flat out scary)

    I won't build a closed up fortress like the ultimate secure home, because I want some natural light. I'm not sacrificing much in the way of security, though - the southern wall will not be completely exposed, and it will be of thick ICF construction. I also plan to be able to shutter the windows with shutters so stout that the ICF wall is probably the only thing that will hold them up.

    All that's left is to get moving o this project is deciding on the parcel of land. Other than eliminating a couple of candidates, I've made no progress at all since my first post, dangit!
  18. Maxflax

    Maxflax Lightning in a bottle

    We're at the other end of things, we have owned our land for near 20 years and it is perfect for our intent. We have been waiting for the cash to build, that's all. It looks to be possible, soon. The road and home site are done and secured with heavy steel gates, no one has even tried them in 20 years

    We'll live in town 30 miles away, but I'm going to buy a cheap RV trailer and likely take on a helper who can stay out there free, etc in return for helping me build and keeping an eye on the site. I'll be out there some nites, others not
  19. hank2222

    hank2222 Monkey++

    when it comes to earth sheltered home drianage is the biggest problem with the system and i can tell this why ...i have a underground home in Az not far from Nadja and when i put it in last year i made sure the drainage system with at least four ft wide of a peagravel rocks allowing the water that did drain down from the topside soil when it was raining or winter time effect of snow on the ground and the melting snow would soak the ground ..

    the rocks acted as a way to keep the ground water to be channeled into the french drains away from the wall of the cabin and all underground homes should have a french drain trench with peagravel and small fine layer of sand to act as a water drainage system to keep the water away from the walls of the place.. ..so with a propler coating of the outside wall with two diff coatiing starting base line coating was Line -X- coating then a Sherman Williams tar base coating then a another coating of the Sherman Williams tar base coating after the unit was assmbled and ready to covered up
  20. Kingfish

    Kingfish Self Reliant

    I would start with an earth covered home. Wood heat via outdoor boiler thermostat controlled. Solar power 120 volt interior and high efficiency appliances. Then again the Sterling engine comes to mind. Kingfish
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