Building an Earthship in a Cold Climate? STOP

… and read the book Passive Annual Heat Storage – Improving the Design of Earth Shelters by John Hait.

  • Should Earthships be insulated? Yes (but not in the obvious way it’s being done today).
  • Should Earthship floors be insulated? No.
  • Can an Earthship provide a comfortable (21c) climate using passive means during the winter season in a cold climate? Yes.
  • Can heat be collected and stored during the summer for a winter with very little (mostly cloudy) passive solar gain? Yes.
  • Can an Earthship be properly ventilated without having to sacrifice precious heat? Yes.
  • Are skylights a must? No.
  • Is the corridor wall (introduced systemically in Global Model) Earthships required in cold climate? Not necessarily.
  • Can an Earthsip be built in clay-rich expansive soil? Yes, if the soil kept dry.

When it comes to cold (moist and frozen) climates like ours here in Romania, there are quite a few things that felt, to me, incomplete, missing or even wrong in Earthship design (including the latest and greatest Global Model). To me what was missing most is the lack of explanations of how things work and why they are designed the way they are. I could not find satisfying answers in any of Michael Reynolds’ Earthship books (Earthships have evolved way beyond their description in the original Earthship books) nor online in many of the documented builds and open discussions about Earthships.

Then a few days ago I published this post about ventilation problems in an Earthship and began to compose my thoughts for a follow-up post. The solution seemed to come in the form of earth-tubes. The first resources I came across (pretty much as they were presented in the search results) were:

  •  Wikipedia – which provided basic technical information.
  • The Natural Home – which provided a convincing argument for earth tubes.
  • BuildItSolar – which raised some questions and left me with some doubts.

Luckily I stubbornly pressed through a few more pages of superficial search results and on the 3rd or 4th page found an article by John Hait inaptly titled Umbrella Home. The article blew me away. I ordered the book and couldn’t put it down – I read it word for word in just over a day and will be re-reading many parts of it again.

The book truly lives up to its subtitle “improving the design of earth shelters”. Not only does it open a door to a much deeper understanding of earth-tubes but to do so it introduces a fantastic concept of a large insulating/blanket which surrounds an earth-sheltered house in which earth-tubes can really come to life.

The core idea (backed up by accessible explanations and practical research) is to create an insulated and water-proof blanket that encompasses the house and a large area (~6 meters) around it (which can be achieved with more or less the same amount of insulation materials used for standard wall insulation).

This insulated umbrella creates a large body of earth which is dry and functions as a huge thermal battery attached to the house. The house itself acts as a solar collector to slowly charge the immense thermal battery during summer. Then, during winter that battery slowly discharges heat back into the house.

Earth tubes are used with this umbrella (in a way that could not achieved without the umbrella) to passively generate both ventilation and temperature regulation (cooling & warming) of the house. Because the earth-tubes run through the thermal battery surrounding the house they work as a super-efficient heat exchange system. A passive air-conditioning AND heat-exchange system that is simple and affordable.

 

As a cherry on top  – imagine running an uninsulated water supply pipe under the umbrella and having water preheated to 21 degress (celsius) during winter  (cold water supply has to be insulated under the umbrella). As someone who washes dishes with freezing-cold water (unless I fire up the wood boiler) I am watering at the mouth at the thought of washing dishes with passively heated (no additional energy expense or effort) warm water. Not to mention energy savings in heating bathing water.

This may cause a problem with Earthships that include rain-water harvesting stored in buried cisterns. The cisterns, if buried close to the house, under the umbrella will become a source of warm water. Cold water would have to be cooled somehow and I don’t know what effects this may have on the stored water. Since we’ve decided to forgo rainwater harvesting and put in a green-roof this is not a problem for us.

If you’ve already built an Earthship in a cold climate and it isn’t functioning as well as you thought it would I believe that at least some of the measures described in the book can be added to your Earthship to make it a much better home.

I don’t recommend trying to implement this from the basic information in the article. I STRONGLY recommend reading the book word for word. It is educating and empowering and fun to read.

I am now (again) heading back to the drawing board to revisit and rethink our house design. I feel I know better now and I am grateful to John Hait for his work and for making it available to others.

11 Comments

  1. Posted January 28, 2012 at 8:35 am | Permalink

    http://www.zeroenergydesign.com/Passive%20Solar%2

    How about this ZED concept of passive solar heating:
    – 2nd is hitting floor of 2nd greenhouse all day
    – heat rises to ceiling of 2nd GH
    – it pulls air from pipes under the floor
    – this pulls air from behind the tire wall
    – this in turn pulls the hot air from the ceiling of the 2nd GH
    – this will be renewed all day as more sun hits to floor
    – close the vent pipes after sunset and perhaps put curtains over the glass
    – The thermal wrap is now warmer than without this convection

    Explain how insulating the floor is a negative if it's freezing several meters down in a very cold climate.
    This ZED method allows heat to circulate.
    Romania gets freezing in winter. I don't think many people would characterize it as "very cold", though freezing temperatures are real and must be dealt with. If we have all of these natural processes working in our favor, then even if they are lacking something we are ahead of our neighbors who are relying exclusively on fossil fuels. Maybe we only need to run heaters 10-20% of the time.

    • iamronen
      Posted January 28, 2012 at 9:23 am | Permalink

      Hello Bob,

      I looked briefly at the ZED concept (two floors and double-shell) and set it aside as I don’t see how it can be applied to an Earthship (single floor single shell structure).

      We don’t have a climate in which earth freezes several meters down – that sounds to me like a permafrost situation and I have not given such a scenario a thought (maybe underground is simply not a good option in such cases?). In our climate frost depth is about 90cm (unless it is mitigated by insulation). Our water supply infrastructure runs at around 1 meter underground and we have no freezing problems. Romanian pantries are typically built just below the surface and don’t suffer from freezing either.

      As for floor insulation. The umbrella concept converts the earth surrounding the house into a huge thermal-mass-battery that is very slowly charged in summer and very slowly discharged in winter. If you insulate the floor you disconnect the house from the earth beneath it – so it charges less efficiently and cannot conduct heat into the house in winter.

      However, before this discussion deteriorates into a long-standing argument on floor insulation in Earthships, let me reiterate that this is true ONLY if the entire PAHS strategy is applied including water diversion, an insulated and water-proof umbrella (wet earth drains heat from the house), passive breathing ventilation (intake and outlet earth-tubes) and a house design that makes it an efficient summer heat collector (not too much and not too little).

      In the end it’s quite simple, if you do not heat the earth around (including under) the house to the temperature you would like it to be in the winter then heat will be conducted out of the house to the surrounding earth (in which case you are better off putting in insulation).

      I completely agree with you that the goal should be to reduce fossil fuel dependency to a minimum. I want to cut down as few trees as possible.

      I warmly recommend you read the book end-to-end. It is one of the most impressive books I have encountered on these issues.

      • Posted July 14, 2014 at 6:14 pm | Permalink

        This is what Mike assumed in many of his European ‘failed’ concept. Indeed examples of earthships WITH floor insulation proved quit the contrary. Look at Groundship in Brittany and reference “Earthships in Europe” http://www.lowcarbon.co.uk/publications

  2. Mike Innes
    Posted January 25, 2013 at 1:26 am | Permalink

    So what do you think about this design for Scotland? Scotland has an Earthship but it was built along the Mike Reynolds lines and simply wasn’t appropriate for a damp, Northern European climate! I ask because we are much further North than Romania and we don’t get such warm summers (if we even get a summer – ha!) We also have a VERY damp climate, the dampest in Western Europe. I think the closest equivalent to you is Slovenia! This has given me more hope for building an Earthship home in my homeland!

    • iamronen
      Posted January 25, 2013 at 6:17 am | Permalink

      In all our “sustainability” learning and application efforts I’ve come to appreciate that is always a gap between theory and practice. That gap can only be filled by personal, patient experimentation that takes place in your own unique environment. For quite some time now I’ve been convinced that Earthship design is not right for damp climates. But what bothered me most was that I couldn’t find any explanations on the reasoning behind Eartship design … knowledge that would better empower me to make my own decisions.

      That is where this book comes in. It gave me plenty of insight into the workings of an underground home (regardless of the construction technology/materials you use). I am convinced that even Earthships that are built in more forgiving climates can benefit from (and be improved with) the information in this book.

      I wish I had a clear answer to your question but I’ve never experienced your climate. I can say this, if an underground home is suitable for your climate then the knowledge in this book is priceless … and if not I’d probably look at construction with hemp http://bhudeva.org/blog/2011/02/07/building-with-hemp-book/ which seems to be more available in your part of the world.

  3. Ty Brodale
    Posted March 8, 2013 at 5:27 am | Permalink

    There is a company here in Iowa, USA that installs earth air tubes 8 ft deep. Their customers run them in the winter in all temperatures because the fresh air will come in at a stable temperature as much in the winter as in the summer. So in other words your plan looks great :-)

  4. Mel Babb
    Posted July 23, 2013 at 8:07 am | Permalink

    Where are you going together your water from now that you have gone for the living roof option?

    • iamronen
      Posted July 23, 2013 at 6:05 pm | Permalink

      we are thinking of building a 2nd light structure (workshop, open kitchen, wood storage) slightly uphill from the house and it will have a standard metal roof that will collect rain-water for the main house (though I still have unanswered questions about rain-water storage in our climate).

  5. Roberto Pokachinni
    Posted March 14, 2014 at 11:29 pm | Permalink

    I’m curious what Mr. Hait says specifically about condensation and moisture in this system. Is your design involving the greenhouse typical of ES design and involving a lot of plants transpiring in your system? I mean without having a skylight vent? I like the idea’s that you are presenting. I am possibly going to be taking over (after the snow melts here in Rocky Mountains, Canada) the foreman position on a three module classic earthship that is already 5 tires high. Here we have an interior temperate rainforest/boreal forest transition, with often deep snows, and rain throughout many parts of the year. Winter is pretty much half of the year, and often it is not sunny. Soil is clay/silt which holds a lot of moisture.

  6. Alexandru Fleseriu
    Posted June 15, 2014 at 7:19 pm | Permalink

    Hi Ronen,

    We visited you this week, I am Alex from the group of architects studying the Peasant’s Box in our project for South Africa.
    I would like to read the book but the link appears to be broken. Is anybody else having this problem?

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