Adjusting Earthships for Freezing and Wet Climates

I'm currently an Earthship "student" and plan on completing my field studies this summer in Reno NV. I also have begun some plans to build an Earthship in VT/NH. I'm reaching out to other Earthship builders, Earth builders with questions about tweaking an Earthship Inspired structure for Freezing Climates. Especially since our frost line is at Five feet, and during the coldest months we may have cloudy skies for three straight weeks at a time.

So some of my concerns are:
Harvesting Water over the winter
-Insulating Cistern or carrying it under the frostline?
-Snow harvesting?
-Are Glycol tube systems in gutters all they are cracked up to be?

How the frost line will effect the Thermal Mass and Passive Annual Heat storage?

Vapor barrier exteneding under the house?
Burnt Course of Tires ramed with gravel vs dirt?
Possibly insulating under floor, would it help or actually hurt PAHS?


I appreciate your thoughts any suggestions!:)
-Ash

If you use the umbrella design of PAHS I think the frost line will stay at or near that level from what I've read, or at least make it higher than normal. Perhaps having the cistern under it would help protect against frost issues? I think insulating between the living space and the earth reduces or eliminates the thermal mass benefits. I've heard having a vapor barrier on the floor and covered helps reduce moisture issues. If the umbrella extends out around the living space and tapers down to allow moisture to flow down and away with gravity, then moisture should be less of an issue too. Would you use the air tubes to draw warm/cool air in year-round like in a PAHS design?

I haven't personally done anything yet (just got my property, driving up tomorrow to plant trees) so all my comments are based on reading about others.

Do you have the sandy soil that is common in that region? If so, I think you could benefit from thermal storage as long as you can keep water away from the structure and its umbrella zone. Be aware that the stable ground temperature is similar to the average annual air temperature, and where you are, will be sucking heat out of the bottom of the mass forever. Coupled with the cold cloudy weather you get, I would not think that trying for totally passive heating would be the best return on your money or effort, even though it might barely be "possible". I would go with a combination of mass and an efficient steady heat source like a rocket mass heater. If you have even a few acres to devote to it, you can harvest all of your own fuel.

Ashley,
I am not an engineer, but I've done a lot of reading on this very subject.
In our climate (I'm in NH), you would benefit from creating a large mass within your building envelope that is insulated from the exterior. You could do this by digging your basement hole deeper than normal, adding a layer of insulation not only around your footings and walls, but below what will be your slab as well. then back fill fill your basement to normal basement elevation, and pour your slab. this will give you a large thermal mass that is isolated form the heat sucking ground below us. This is one variation of a "climate battery".
Hope this helps
Jason

How much water harvesting will you need to do during freezing conditions?   I haven't lived in your area, but I doubt it stays below freezing temps all winter long.

The amount of water needed inside an Earthship is relatively low.  While I don't know for sure, I'd guess at most perhaps 25 gallons per person per day(probably less)?  If you figure 2 months of below freezing weather, that works out to about 1500 gallons per per person, it should be fairly easy to build a 5-6,000 gallon storage tank directly below the earthship and that much water will help moderate the internal temps.

As soon as the temps get above freezing the snow will melt and you can catch meltwater to fill your tanks.  Worse case, you bring some snow inside in buckets and let it melt.

I'm currently an Earthship "student" and plan on completing my field studies this summer in Reno NV. I also have begun some plans to build an Earthship in VT/NH. I'm reaching out to other Earthship builders, Earth builders with questions about tweaking an Earthship Inspired structure for Freezing Climates. Especially since our frost line is at Five feet, and during the coldest months we may have cloudy skies for three straight weeks at a time.

So some of my concerns are:
Harvesting Water over the winter
-Insulating Cistern or carrying it under the frostline?
-Snow harvesting?
-Are Glycol tube systems in gutters all they are cracked up to be?

How the frost line will effect the Thermal Mass and Passive Annual Heat storage?

Vapor barrier exteneding under the house?

Possibly insulating under floor, would it help or actually hurt PAHS?


I appreciate your thoughts any suggestions!:)  

I'm in a similar climate to you.  Reno is not at all similar, so you will not gain the 'experience' that you will need to figure that out in your climate. I'm not saying I have all the answers.  Passive solar is great, but it is Way Better if you are in a sunny winter location, like New Mexico, Nevada, et cetera.  You are in a very different climate, and I'm not saying that it can't be done, but I'm suggesting that you should probably sit down and brainstorm with your instructors and fellow students to make this system compatible with your climate.  You are thinking the right things, I think, by asking the questions that you are.    

My suggestions.  Don't try to harvest water in the winter.  Depending on your roof size, and considering your maritime like cool temperate climate you likely get enough water coming off an Earthship roof in the thawed months to fill your cisterns; make or buy bigger cisterns.  That is way easier then dealing with all that other headache of trying to harvest winter water.  Harvesting snow is not a very efficient way to get water.  Snow always has a lot of air in it's crystalline volume, particularly when it is really cold and dry.  When it is wet, obviously it has less air in it.   Also, a lot of snow will sublimate into the air when it is really cold, before it has a chance to melt.  Another problem is that your gutters will get ripped off by ice and or heavy snow.  A lot of people remove their gutters in the winter because of this.  I have no experience with glycol tubes in the gutters.   I say go low tech and don't try to harvest winter water.  That said, I have read about a family that made a chute that brought snow down off the roof, and into the house against their woodstove, where it melted into a pool at floor level that they could dip into.  Pretty low tech and effective.  The book was called Wilderness Mother. It's available pretty cheap at amazon It's the true story of a family homesteading in the remote North Coastal Mountains of B.C., Canada.  They get a lot of snow, and it is wet snow.  You may be able to get the book from inter library loan.  Not sure.  

If you figure 2 months of below freezing weather, that works out to about 1500 gallons per per person, it should be fairly easy to build a 5-6,000 gallon storage tank directly below the earthship and that much water will help moderate the internal temps.

 I would put this tank in the berm behind the tires.

I don't know how thick the insulation has to be. but an insulated roof on your cistern will go a long way.  The frost has to penentrate, steadily to go deep.  Insulation stops this steady penetration, and the depth of water acts as a thermal battery, resisting freezing deeply.  Also make your cistern walls slope outwards at the top if possible so that if you do have the top freeze then it has room to expand.

Dealing with big frosts AND cloudy weeks on end, is not ideal in Earthship design/function.  You will want to have a rocket stove or some other heating going on besides your passive solar.  The frost/ extreme winter weather will be too much, and there will be no way that passive solar will be adequate to sustain the house at a comfortable temperature with long solar delays like that.

In my thinking, your thermal mass/passive storage has to be supplementally charged with some other heat source besides the sun, considering your climate.  If you don't have an alternate heat source, on sunny days / weeks, you will be able to live comfortably, but only after the initial chill has been removed by the first day or two of sun hitting everything and charging the 'battery'.  With an alternative heat source, you will be able to charge this and keep it charged, and thus be comfortable all the time.

I would think that extending your insulation, and PAHS umbrella outwards further in all directions will enable you to gain a larger heat battery.   Think of this as being a buffer between you and the outside air.  As an example of how this works, an unheated but enclosed porch that you have to go into in order to go to your main door, protects that door from the extremities of the weather, be it hot or cold.  It's not warm in the porch in the winter, it's simply warmer than outside, and it has no wind, so you lose less heat to the outside, and allow less cold inside.  In the case of a PAHS house, you are enveloping your house with a buffer so that the extremities of the weather are kept at a distance.  Think of it also, obviously, as being a thermal battery which is storing summer heat, and storing solar gain, and (in my mind necessary) storing probably the heat from a rocket stove.  This is like having your porch buffer heated.  I don't know much about the PAHS heat transfer tubes and how they work, and what their volume has to be, so I won't discuss that at all.  What I will speak again about though is insulation and umbrella.  Insulate outwards in front of your house beneath your glazing, as much as you can afford, and put your umbrella out there too.  This way the frost has to go around that outer edge and creep back toward your Earthship foundation.  The frost will struggle to do this more and more as your umbrella slowly dries out this dirt.  Insulate and spread your umbrella outwards behind and on all your bermed area of your house as far as you can afford, and if possible backfill with loose dry materials.  The dryer the better, as wet material is not insulating at all.  Build and experiment with insulating your Earthship windows so that you can keep your daytime heat in the house at night.  Have alternative lighting so that on super cloudy periods you can close your insulating window covers, if you want.    

Burnt Course of Tires ramed with gravel vs dirt?

 I'm not sure what you mean here?  I'm not familiar at all with a burnt course of tires.  I'm thinking you might have meant to write First Course of Tires, considering that you are suggesting gravel over using dirt.  I would ask Mike Reynolds, or other Earthship Academy folks about that.  I think it's probably a good idea to have more drainage in a wet environment, but I also think that this can be totally accomplished with a properly done umbrella.  

Instead of insulating the floor, I would heat it, with pex tubing and a wood heated system, or keep it warm by keeping your space warm, and insulating the space well beyond your thermal mass in all directions except downwards. Down is your constant thermal battery, which, as has been mentioned is generally the average between your high and low regional temperatures... but this is also charged by your building being warmed by the sun (and alternative heat source) and being insulated from heat loss. The warmer you keep your building, the warmer your floor will be.  But in floor heating will be a huge bonus boost to this, if you can manage it.  But that isn't super low tech.  :)   but underground housing in a cold damp place calls for some drastic measures, maybe.
     

Earthships in the NE... something I've thought a bit about.  My (admittedly non-technical) understanding is that passive solar and thermal mass don't work very well in overcast climates.  Additionally, the NE doesn't have the wide diurnal temperature shifts of the SW, so mass in contact with the earth doesn't actually stabilize your temperature, it just makes it slower to heat and slower to cool.  Un-insulated thermal mass only works when you have a moderate average temperature (as you do in the high desert, though not in a NE winter).

Now, mass within your insulated envelope will absorb heat from a wood stove and raise your winter temps, giving you better results with a non-constant heat source like wood burning.  But, in the summer it could soak up heat and release it during the night (something you don't want, assuming you are off-grid without A/C).  There are advantages to moderate amounts thermal mass in a NE climate.  However, your money and effort would best go towards insulation.

My (very vague, general) plan would be to maximize insulation with a straw-bale or cellulose design, including some thermal mass like a small indoor fish pond, insulated concrete floor, etc.  Then you run earth tubes (buried six feet down with a trencher) outside for cool air in the summer.  You can run fans off an affordable solar/battery off-grid system to power the earth tubes.  I kind of doubt you can run a geothermal heat pump with an affordable off-grid solar designs.  You shut the earth tubes off during the winter, as the 50 degree air they blow will not help you heat.

Ah earthships...

I like the idea of insulated mass within the building envelope as a boost to annualised thermal inertia. Passive solar gain will avail you not at all in a largely overcast winter. I second the RMH suggestion.

I still would like to know what the perceived advantage is of using tires over, say, conventional concrete forms (or even better, Insulated Forms that stay in place) and a rammed earth method. They are labour-intensive to pack and to move once packed, and they're far from an ideal size and shape for the building of walls. Not to mention the fact that they must be encapsulated completely or they offgas as they break down.

It seems an expensive and back-breaking way to dispose of other people's waste to me.

-CK

I see the concept of trying to build an Earthship in snow country a bit like thinking about an Igloo in the tropics.
Aren't both designs specific to the regions they were designed for?

I'll nip it in the butt on a few misinformed statements. First, you can use passive solar in virtually every environment between 56 degrees N. Latitude and 28 degrees N.L. and equally on the southern hemisphere. In fact, you can do so outside those boundaries. Since Earthships and Earthship-like homes and buildings would and could apply other passive solar systems. You must adapt the window aperture and thermal mess and in this case, you must also insulate to stop the effects of thermal bridging. Earthships and like homes are largely under earth grade, you must account for thermal bridging even more so than an above grade home with just footings in the ground.

You can not use the same size thermal mass and window aperture for Nevada and use it in Vermont or other similar locations. You have deep frost depth. Another technology I would recommend tapping into the use of is the use of ground source heat pumps (GSHP) or often call geothermal heating and cooling system. This uses the passive solar technology of using thermal mass of the Earth itself.  Since all this heat is permeated into the ground from the sun including deep heat that is also charged by solar energy that passes literally through the earth but you'll be pretty shallow depth so not useful for geothermal power. Do not confuse the two different kinds of geothermal. While based on the same concepts, they have dramatically different requirements.

To generate power, you need ground temperatures hot enough for water to practically turn to steam. This is unlikely what you'll ever find at an affordable level in Vermont. It would be cost prohibitive for a singular house in practice. Geothermal heating and cooling would be appropriate technology because it operates on the principle of heat exchange like how a refrigerator work. You can read up more on it. This combined with passive solar would keep things in good shape for your Earthship-like home.

You may require modifying the size of thermal mass and window aperture. If for a variety of reasons, you can not use the size windows and thermal mass that you would need due to client needs for year round, you may want to consider supplementing with geothermal heating and cooling.

I'm also considering earthships in VT and am wondering if you've been successful?