allerton abbey wofati 0.7: the second winter

David Livingston wrote:Supplimentry heat . Need this be from a fire/stove ?
Why not from animals ? Either have a two story building with cows goats sheep horses living on the ground floor and warming the ground second floor bit like a Bastle . Also some one mentioned Dogs Didn't the native americans have a breed of dog for such ? ( I could be wrong about this )

That would be a whole new design. Not everyone is happy to live in a "barn", though maybe willing to put up with it rather than freeze. Many "lap dogs" were bred as hand/lap warmers and large dogs have been used as hot water bottles too. (in some cultures wives were "used" the same way... personally I am glad we no longer think of people as possessions) "Two stories" and "mass based" generally do not go together, though. Dogs are probably more work than a fire.... a good farm dog would probably find our comfortable inside temperature too hot, so it would not be possible to stack uses in that way. A dog who felt comfortable inside, would not be happy being inside while their family was outside working all day and would tend to poor behaviour. An inside temperature that Paul seems to be aiming at could probably not be achieved through animal heat, though the straw bedding and animal waste products might come close... if you liked the smell.

I am thinking that if the home design brings the inside temperature close to comfortable, that supplementary heat would not be very much if an efficient heat source was used (high mass heater). The fuel could easily be things like pruning bits (keeping paths clear for example) and not full trees. A cooking setup designed to also heat could stack functions well too. There are a number of cooking setups that have summer and winter modes for this purpose... though I really like the idea of an outdoor covered area to use as a summer kitchen. There are some areas where outside is too warm in the summer though and being able to have a nice cool "cave" after being outside would be nice. The climate is really important to design. I only have two places where I have lived to go by, Calgary Alberta Canada (similar to Montana BTW) and the west coast, Vancouver and Vancouver Island with a much milder winter... and more seismic activity(several tons of roof seems less desirable here).

RMH designs for the wofati might be better with the feed opening level with the floor and most of the flue below floor level. The barrel would still give "instant heat" while the floor mass would add it later. It would be interesting to build an RMH that could direct the flue through the floor or through a bench to see what the difference as felt by the occupants would be. The through the floor design would of course leave more floor space in a smaller home. (there is more to think about than just effective heating in other words)

I am presenting lots of ideas here, but most are off the top of my head. I am sure many can be thrown out by those with more experience, but maybe one or two will prove useful.

I know that it gets hot, but what I'm saying is that the peak temp is only held for a few hours, and the 24 hr average (not yearly average) is considerably less than 90. So, a mass temp of 90 degrees is a complete impossibility (in my opinion) barring some impressive climate change or a significant contribution from below (that I don't think could be produced by humans and their daily activities, but of course could be produced by some sort of heater).

I would love some information about what this dwelling was like in the heat of summer. Was it delightfully cool? I would imagine that it was. I think this is worth a great deal when you are living off grid and energy intensive appliances like A/C are non-starters. For me, relief from heat in the summer, and reduced need for fuel for the RMH is plenty of reason to put on the umbrella of dry soil and sawdust.

I don't know what the solar capabilities are, but I don't run the heat in our store during the winter (not nearly as bad as Montana) but we do stay below freezing in the winter. Florescent lights put out all the heat that we need during the winter, except on days we are closed. I don't know what your feeling is about those lights, but just a thought.
Another thought for getting heat inside is a wood cook stove. I have several friends that use these stoves (with water barrels on the side) not only for cooking but that's their source of heat as well as hot water. I appreciate the goal of the mass and this in strictly to make the space livable for this winter.

paul wheaton wrote:

I think in some areas it would be helpful to make use of solar gain during the summer to overheat part of the mass such that the heat arrives at the living space at the coldest time of year.

It is possible that we might want to implement a design variation if we want a to warm some of the outer mass up to, say, 80 in the summer .... or maybe even see if we can get it up to 90. With the idea that we might harvest some of that in the winter.

I was thinking 100 plus actually Because the heat will not just travel in a straight line... in fact half of it may go the wrong direction (though an insulated wall may help) and will spread out as it moved. It would depend on the "glass" area of the heater of course and I am thinking a smaller area is easier to protect in the winter from snow build up etc. than a large area and of course the cost of materials wants to be as low as possible too. So my thought is smaller and hotter. Larger and cooler would allow stacking functions by growing things in there when it was too cold outside.

Luxuriant means what temperature to you? I am working outside this past week at 3C/36F (actually when I first go out it has been subzero/freezing) with short sleeves and some of my co-workers are still wearing shorts. I would find 21C/72F a bit warm, but I know there are some who would prefer 78F (my MIL who is late 80s). I agree 76F would feel wonderful in the summer though and as you said windows can be opened. In any case it seems that the aim is high (as in higher than some people will find comfortable) with the idea that it is easier to cool. I am sceptical that this can be achieved without some kind of extra heat, but agree it is a great goal.

Through the process of researching for building my own passive solar home I've come to believe the notion that it's only about the first two inches of mass that's really effective for conditioning the living space. For a cold climate situation if it were cold enough inside for heat energy to conduct out of a wall or floor from deeper within the mass it would probably be colder than the designated luxurious range. If this inner mass was significantly warmer like the 90-100 degrees F mentioned, then it might work but there is the question of how do you get the innards of the mass that warm without making the living space too warm in the process, maybe timing is everything there!

Before everyone jumps at me for saying there should only be two inches of mass I want to be clear that I think additional mass has definite benefits because the long term thermal inertia acts like insulation. For example if the mass is three feet in a normal situation it could be 45 F a foot away from the living space and 0 F outside. And of course the properties change if the mass is a liquid because then convection can occur within it not just conduction, then the 2 inch rule doesn't apply.

So, one strategy to improve the Wafati design could be to add more interior mass with lots of surface area. How about something like a gabion but with a timber cage instead of galvanized wire? Look to nature and you could probably find lots of inspiration, right now I'm thinking of a magnified image of biochar.

TWO SUGGESTIONS:

(1) Do you have or can someone send you a long probe compost thermometer to insert between the logs to track the mass temperature?

(2) As suggested above the floor is sinking a lot off heat. If instead of building a bench you dug down and put the exhaust tubes under the floor you would have a radiant heat floor.

Is there any restriction against window coverings that are used at night? A white insulated quilt as curtains could be helpful both summer and winter. In the winter it would both keep heat in by insulation as well as reflecting radiated heat back at inhabitants. Natural light is important, so I would not suggest using them during the day unless the home was empty. (maybe this is already being done) I am wondering what other simple things can be done to increase the delta temperature from inside to outside and to make a lower temperature "feel" warmer. I think the use of materials that reflect heat radiated from the body back to the same body is underutilized in today’s buildings.

Another thought I had, is if it would make sense to add mass inside the wood post wall. I am thinking in terms of rocks or maybe cob. I am thinking the surface may be able to release heat faster than the wood would be able to... I know the question still is how does it get "charged" first. Maybe wider spaced between the logs in the wall that clay can be packed through to transfer heat from the mass faster.

Does anyone know if a flat surface radiates heat in a directional manner at all (could it made to)? Would tilting the wall up or down or sideways make the radiation reflect off the wall/ceiling/floor rather than go out the window?

Julia, I think you have a really good point about the average daily temperature in Montana. Yes it gets up to 90 but it also gets down to 54 (average) at night even during the hottest month of the year. The average temperature for the 4 hottest months of the year is 65 degrees. If the heat travels 9 inches per month you could conceivably heat 3 feet of mass up to 65 during the hottest time of the year and it would be colder than that for the rest of the year.

Paul, I would guess that the sum of all of the human heat sources A-D barely covers the losses from the end walls, windows, doors etc. If the building were tight enough that all of this heat were retained then it would require some sort of air ex-changer to keep the air fresh. Just my 2 cents.

I could really see these structures working beautifully and hitting "luxuriant comfort" with a bit of passive solar incorporated into the design. I know the goal is to prove this isn't necessary, I just don't see why not to capitalize on a natural, freely available and consistent resource. I've stayed in small cabins that stay luxuriantly comfortable where heat is only needed during extended cloudy periods. There is nothing fancy with these cabins, just good solar exposure and straw bale insulation on the east, west, and north walls, along with blinds that are closed at night for extra insulation. And that's without a big thermal mass to buffer the temperature and store it between seasons. If a large thermal mass were incorporated I imagine structures like this one wouldn't require heat even during extended periods without sun.

I could really see these structures singing with some solar gain used to heat the thermal mass. I was a bit shocked to come back to Bozeman to find out that a greenhouse I recently finished actually has stayed warmer than 0.7 despite a bit colder weather in Bozeman. It's been below zero at night yet the coldest the greenhouse has hit was 36 degrees f, yesterday it was 45 despite the lack of sun as it was snowing all day. Keep in mind this is a very poorly insulated roof (r-2.1 greenhouse glazing) with lots of south facing windows that also act as a big heat loss. To me it seems that the solar gain during the day offsets a big chunk of the losses at night.

The original drawings Paul did had a glazed roof over the north entrance with a berm or bank north of that. I think this is a necessary element for your environment.
(1) The solar gain in the north berm/bank would moderate the night temperature on the exposed wall.
(2) The protected area lengthens the food production season for the residents.
(3) The glazing with proper gutter installation collects rain and snow melt from the thermal storage below which can be stored for garden ans washing purposes.
(4) The stored water is an additional heat sink.

If this is built next year Then the batch heater could be moved to the outside to heat the air to keep plants from freezing in extreme weather events and the mass whether floor or bench could be on the inside.

From my experience in Northern Maine that is what I would do.

Zach Weiss wrote:
I could really see these structures working beautifully and hitting "luxuriant comfort" with a bit of passive solar incorporated into the design. I know the goal is to prove this isn't necessary, I just don't see why not to capitalize on a natural, freely available and consistent resource.

If I want to be ____ (put whatever word you prefer in here), I would say that all the heat in a wofati is solar anyway. The only difference is to try non-direct solar. That is none of the solar input is through glazing into the interior. The air temperature accounts for less of the heat gain than one might imagine. I think a lot of the heat gain comes from direct Sun radiation on the earth at or near the edge of the "umbrella". This heats the ground in this area which after making it's way downward goes under the umbrella and starts travelling towards the dwelling. Yes this takes years. A PAHS design is expected to take two to three years to heat up on it's own and almost no one does not add extra heat somehow.

Radiation is a much bigger portion of air temperature than most people are aware of. The past week here has been clear and sunny, and the temperature has gone down, there has been frost (first time this year). Next week we are told to expect cloudy skies... and warmer temperatures... well mostly warmer lows. We can expect the lows to rise from -2C to about 5C while the highs will only rise from 5C to maybe 8C. This is all to do with radiation rather than convection or conduction. (Len will be back to wearing shorts to work )

So the point is not what the air temperature is on average. The air temperature is heat convected from building surfaces, leaf surfaces, ground surface, etc. Many of those surfaces are low mass, they heat up quickly and warm the air quickly too, but they radiate (on a clear night) directly to -273C deep space once the sun goes down and can be up to 10 degrees cooler than the air by sunrise. The high mass earth, on the other hand, aside from being high mass and storing some of the daily Sun radiation deeper down (remember more Sun hours than dark for 6 months of the year), but also has more cover being lower down. That is much of the land is shaded from the night sky radiation sink by trees, buildings and even grass to some extent. It is worth noting that in most places, the peak summer temperatures (air temp) occurs after the longest days, often by over a month. SO where does this extra heat come from on these shorter day when the Sun is at a less direct angle to the earth? The earth itself is what controls the air temperature and it keeps gaining heat for close to 6 months (4 to 5 months is probably closer to correct as the temperature does seem to go down before Oct 21... though again that is the air temperature not the earth temperature).

Heat travel and either encouraging it or preventing it (well slowing it down) are not well understood by most people, even those who deal with these things for a living. Most standard insulation deals with conductive radiation only. I have not really seen anything that is purposely done to prevent heat travel by radiation. A window that is rated to have an insulating factor of R6 will still allow 95% of the radiated heat hitting it to pass right through. However, no one wants to live in a house with no windows. (no building code allows lived in rooms not to have windows for natural light and egress both) Air movement seems to be well understood to the point most people now live in unhealthy homes that are sealed tight. A well designed, high mass house, should be able to feel luxuriously warm at a lower air temperature than a low mass heat by air temperature house. A high mass house should be able to stand a much higher air movement even with no heat exchanging than a low mass house even with heat exchange because the residents are heated by direct radiation rather than air conduction against the skin. This is easy to test (I do often) by being outside on a day that is slightly too cool for short sleeves and walking from the Sunshine to the shade. Even with a breeze to ensure the air temperature in the Sun is close to that in the shade, I feel much warmer in the Sun than the shade.... this is why we seek shade on a Summer day, there may be a slightly lower temperature in the shade, but the biggest difference is being out of the radiation. I think the placement of windows in a house is very important. I suspect the angle is important too. I do not think it is good practice to have a radiating surface (heat mass or stove or whatever) with a window perpendicular to the radiation path, I prefer as much as a 45deg angle. I think the floor should not be reflective because it could reflect the heat radiation right out a window. I think the ceiling should be angled to reflect the heat back down to the floor away from windows... that is, a heat source should be under the highest part of the ceiling. I am assuming the ceiling will be quite heat reflective as we don't want to heat the ceiling as much as the floor and the area directly above the floor. If the heater is against the outside wall because that is where the ceiling is highest, then the wall behind the heater should be as reflective as possible. (well insulated goes without saying)

I suspect the manner in which things outside of the windows (and even unbermed walls) also makes a difference. Any kind of wall that is positioned so as to reflect heat back into the dwelling could be a plus (I am talking walls used as fences, not walls that are part of the building). Overhangs that prevent any radiation towards the overhead sky to 45 deg. angle should be considered. One of the suggestions I have heard/read is to prune trees just where they block the view and leave the upper part of the foliage intact to prevent night sky radiation losses. (I think they were thinking daytime overheating )

One of the things to remember about radiation is that the air temperature the radiation moves through does not effect the radiation at all. That is heat that radiates through a window from a 72F room to -10F outside air and is reflected back in through the same window can feel warmer to a person than 72F. Our green houses (our whole earth heating through the seasons for that matter) depends on this. The heat from the Sun spends 14 minutes travelling through -273C space to get to earth and can still heat a green house to 30C on a winter day... for that matter it can be used to melt steel if focused a bit. Things can be baked with no concentration, just plain glass over an insulated box.

Anyway, I am way too long winded.

I will not try to tell you I understand exactly how this all works. I don't, but I do know that radiation plays a much bigger part in the picture than is obvious. I wish I had the space and probes and monitoring gear to show some of these ideas in a way that makes more sense and provides more answers more for my own interest sake, but also to be able to share it.

Len Ovens wrote:
Normally, a Waftai should be warmer than 10C, but it may take a year or two to get there. (maybe a bit longer as the mass started colder than normal) It should end up at least 10F warmer even with no fire. Once the inside temperature gets above 15C/60F I would consider that "comfortable" overall, but I think I would like to have a "hot spot" for sitting around. 15C is great for sleeping or working though. Having a wood fired cooking stove/oven would probably make a good hot spot. A well designed wood fired cook stove should be able to feed a mass bench too. In a small building like this wofati, it is hard to add a wood fired cook stove without heating the whole building anyway. It will be hard to analyze how much heat is being added by the stove as opposed to the mass.

One calculation you could do would be to weigh the wood as it comes in to be fed to the stove. We used a postal scales to do this for several weeks at a time to get some numbers on our rocket mass heater. there will be some loss beyond that (some water weight, some smoke/exhaust temperature leaking heat back out into the world), but the theoretical BTU value of the wood is pretty easy to calculate from the weight. http://www.chimneysweeponline.com/howoodbtu.htm

The other really simple way to estimate it is to compare the temperature when you're in there cooking for several weeks, with the temperature when you've been gone for several weeks. That gives you an idea what you + stove is adding.


I just did an interview with some local folks who've made a lot of earth-bermed houses similar to this wofati design. They use more processed materials - massy blocks and insulation and so on - and they feel that insulation between the dirt mass outside (and the exposed walls too of course) and then interior thermal mass is key to keeping temps up above that 50's to 60's F range. Earth sheltering alone makes a good root cellar, but to get average temps in the mid-60s to 70 F in our climate takes some manipulation.
They seem to prefer non-rot-susceptible insulation like closed-cell foam, pour foam, and perlite (and I suppose the drainage sand also has some insulating properties in our dry climate). I'd imagine the Wofati ideal would be to limit all plastics and synthetics of any kind, and finding a natural insulation material would be key.
They use solar exposures as well. Don't add much energy except cooking, and as of a month ago they had not needed either heating or cooling.

I've been looking into bulrushes as a possible option for locally-sourced insulation here. Straw's not cheap here, but it might be a toss-up in that part of Montana which is easier to get in quantity. Fur, wool, and feathers are great for smaller areas like sleeping quarters.

Erica

Zach Weiss wrote:
I could really see these structures working beautifully and hitting "luxuriant comfort" with a bit of passive solar incorporated into the design.

I think that you are correct. At the same time, how much can we gain from ATI? That is the primary experiment at this point. If we start to include passive solar right now, then it will complicate the numbers.

Speaking of passive solar: somebody sent us a solar oven. Rick went and did some cooking with it and the temps were several hundred degrees.

Further, let's not forget the works of don stephens: using the heat under a metal roof of 140 degrees and pushing that underground for his annualized geo thermal stuff.

A few decades ago we bought some land in AR and build a small dome. We ran an 18" pipe about 40' out from the dome, about 3.5' deep wrapped in a "sock" laying on a bed of rock then covered with with dirt and planted. The pipe ran to a screened trap door of sorts in the floor. There was a vent in the top of the dome and we'd open both creating a draft of 50ish degree gound temp. It keep the small place extremely cool in the hot summer and was pretty comfortable after about an hour or so in the winter. This was extremely grude, but made this structure comfortable. I know this is not part of the test you are running, but utilizing ground temps and air movement may help - after all, few people have a couple of years for anything they build to be livable year round.

Have there been any temperature readings from deep inside the insulated mass (top, bottom, sides)? If the temperatures there are warmer than the interior space, it would indicate you need better insulation in the exterior walls and windows. Picture windows are nice in the Summer, but they are a huge heat sink in the Winter, especially the shaded ones. If they are not bringing in direct sun, they should have an insulated covering on them.

I second the suggestion that you cover the "uphill" courtyard with a greenhouse. Even a single layer of visqueen would be an improvement. A berm or encapsulated straw bale wall would probably also help.

Have you considered the option of building more wofatis around a central courtyard, greenhouse or great room?

Tim pointed this problem out to me last year. I used the power of wishful thinking to hope that Tim would come up with something and it would magically be solved. Tim did solve this problem by building a new wofati and moving into it.

I guess I really need a 3-D animated drawing to describe this problem, but I'm going to make the best of it with this crappy drawing.

Having some gaps between the logs is a good thing. We need some air exchange between the mass and the living space. Unfortunately, those gaps are open to the outside at the corners of the wofati. So, cold, outside air just pops right in willy nilly. Even worse than that - cold outside air is between the inside living space and the thermal mass.

The solution is to fill these gaps with cob. About 20 times easier during initial construction.

Following along with interest, I am curious as to how this year's temps compare to last year. How did Tim and Kristie get along last year? And how does the new Wofati compare?

Last winter they were in the unfinished wofati 0.7 with a very large conventional wood stove. 400 square feet.

This winter they are in the unfinished wofati 0.8 with a rocket mass heater. 800 square feet.

Tim says that this year they are much more comfortable and are burning 80% to 90% less wood.

If you look closely at the path around the top of wofati 0.7, you'll see that there is a set of turkey tracks using the path (only).

It's pretty icy around the wofati. So Jesse made a cover of pine branches for the path up to the door after seeing Olenka do the same for the tipi. He used the branches left over from making rock jack and fencing supplies.

Hi Paul,

I may be coming into this with not enough background info but is there a reason you chose not to do a heat exchanger for your ventilation?

Neal

Neal Spackman wrote:Hi Paul,

I may be coming into this with not enough background info but is there a reason you chose not to do a heat exchanger for your ventilation?

Neal

I believe Paul is trying to make these buildings as low tech as possible and using as little imported material as possible. The idea is to be able to build a home using almost exclusively materials from the land. Things like heat exchangers and other mechanical equipment cost too much and have a high level of embedded energy.

Correct me if I'm wrong

Simon Johnson wrote:

Neal Spackman wrote:Hi Paul,

I may be coming into this with not enough background info but is there a reason you chose not to do a heat exchanger for your ventilation?

Neal

I believe Paul is trying to make these buildings as low tech as possible and using as little imported material as possible. The idea is to be able to build a home using almost exclusively materials from the land. Things like heat exchangers and other mechanical equipment cost too much and have a high level of embedded energy.

There are low tech heat exchangers for high mass homes that involve running long pipes through the mass at the correct angle that the air will move itself. Normally these are added during build though. Also, they are feared for collection of mold, etc. Keeping them clean is important. I do not know how well they work. It seems the homes made with them just want to live in peace without being questioned about how their home works. So I don't know how well they work or how hard they are to clean, etc.

This is one of the best things about this project (the whole thing not just the wofati) is that the idea is to make the ups and downs public so others can learn from them.

Since last Saturday I have been living in .7 without firing up the rocket mass heater. I've been recording the indoor and outdoor temperatures each day for morning and night. The only source of heat generated inside is from me cooking a meal inside, which usually happens once a day, and my body heat.

Here are the temperatures so far:

2/7
68.0-40
65.3-37.1
2/8
61.5-34.2
62.7-36.1
2/9
60.2-37.9
58.4-41.1
2/10
57.3-38.2
52.7-32.9
2/11
54.3-27.6
57.5-30.8
2/12
56.7-29.8
54.1-28.2
2/13
52.7-25.6

jesse markowitz wrote:Since last Saturday I have been living in .7 without firing up the rocket mass heater. I've been recording the indoor and outdoor temperatures each day for morning and night. The only source of heat generated inside is from me cooking a meal inside, which usually happens once a day, and my body heat.

Here are the temperatures so far:

2/7
68.0-40
65.3-37.1
2/8
61.5-34.2
62.7-36.1

2/9
60.2-37.9
58.4-41.1
2/10
57.3-38.2
52.7-32.9
2/11
54.3-27.6
57.5-30.8
2/12
56.7-29.8
54.1-28.2
2/13
52.7-25.6

Two questions:

1) When was the RMH last fired? That is, there is a downwards trend (at least the first few days) is this because the RMH was fired the day before the start of the test?

2) how comfortable do you feel with these temperatures? Note: I have been working outside in +10C(50F) weather with only short sleeved shirt with complete comfort, so I expect that this is warm enough while working inside, but maybe not for sitting around. Nice to sleep in with a good quilt too.

1- Yes, it was fired the day before the test.

2- The temperatures are fine. I noticed the last couple of nights I've started to sleep with a second blanket. I'm assuming that the temperatures will plateau pretty soon, or at the very least the wofati will cool off at a slower rate.

jesse markowitz wrote:I'm assuming that the temperatures will plateau pretty soon, or at the very least the wofati will cool off at a slower rate.

Actually it seems the temperatures are pretty stable already in the mid 50s. I notice that each day there is one that is higher than the other. Often it is the morning reading. Is this when the one meal a day is cooked? How is it cooked? On what kind of cooker? It seems a propane cooker would require makeup air and exhaust, while a stove or the RMH as a cooker would be much better at making use of heat over and above that used to actually heat the food. So a propane cooker might lower the inside temperature, while a wood fired cooker might raise it.

Also, I am assuming we are talking air temperature.

Sorry for being so analytical.

It would be interesting to see what this looks like another year down the road as the mass gets another heat bump in the summer. A high mass heated home is said to take a few years to reach stasis. This one started with frozen earth and so I would add at least a year. I would say that considering the frozen earth start, this project is doing really well. I am wondering why there is only one cook event and if you would consider that normal or would you expect most people to have two or maybe three cook events a day? It seems to me the design of the cook stove should be an integral part of the design. There should be a balance of heat to food and heat to living space.... I would also guess summer cooking would be more often outdoors. Though that is just a guess... to be complete, temperature readings in the summer should be done too. Notes on things like "I cooked outside to keep it cool inside" would be good too.

Thank you for your work on keeping track of these things. I have yet to build so I am watching close

The meals are super simple- A couple of eggs on one skillet and some water boiling for coffee is pretty typical. I'm cooking with propane right now.

I also think its going well for the first year! Its hard to cook two meals a day in the wofati, because there are so many projects going on at base camp right now. I probably spend more time on base camp that up at the lab at this point. I definitely do notice that if I do cook in the wofati twice a day, and spend a ton of time in there, that the temperature does go up.

I forgot to post this earlier, but the test ended after 9.5 days. The goal was to see how long temperatures would stay above 50 degrees inside the Wofati. Here are the results-

2/7
68.0-40
65.3-37.1
2/8
61.5-34.2
62.7-36.1
2/9
60.2-37.9
58.4-41.1
2/10
57.3-38.2
52.7-32.9
2/11
54.3-27.6
57.5-30.8
2/12
56.7-29.8
54.1-28.2
2/13
52.7-25.6
53.7-31.3
2/14
54.1-25.7
53.2-26.5
2/15
51.9-24.7
54.3-30.1
2/16
50.7-21.6
51.4-23.4
2/17
47.6-21.8

So we had a bunch of days where a fire was kept in the wofati 0.7. Then no fires for over a week.

So a big part of the experiment is the temperature differential. So I'm going to extrapolate Jesse's data to make a list of seven days of just the morning temperature differential and the morning temp:

day 1) 28 (40)
day 2) 27.3 (34.2)
day 3) 22.3 (37.9)
day 4) 19.1 (38.2)
day 5) 26.7 (27.6)
day 6) 26.9 (29.
day 7) 27.1 (25.6)

One observation is that it didn't get super cold outside.

I think that some of the warmth came from the mass of the rocket mass heater.

I still think we need to make the two walls far more insulative. At this moment, I think the best recipe is to make a micro-porch on both sides about 3 feet wide.

mike jastram wrote:Yep, definitely plenty of space! It's more or less north facing - I think the idea is to test the effectiveness of the earth thermal inertia without large solar inputs through the end walls.

Today was rest day so violet and i paneled the upper half of the interior walls today where insulation was exposed. Probably not much heat benefit but a big improvement in appearance! Jesse came up and insulated the door which I expect will help some as well.

10/19 7am 34/52
10/19 7pm 50/57

Just started reading about your adventure. Well done. Two things I noted in your construction. First is insulation. Years ago Mother Earth News got into underground building much like you are doing and found that moisture seepage was an issue. As the ground got moist from rain and such it became the transfer agent of cold from outside to the inside. What they found to work was creating bags of dry sand between the structure and the green earth soil covering stopped the transfer, kept moisture/dampness out and heat in. This is best done with large poly sheets as thick as you can find for durability laid down across the structure and folded up as sand is added to make a bag which was then sealed as the sides and top (just fold it over as you go on the sides and glue it with hot melt or silicon caulking should do I would think but the olds need to be complete to prevent water intrusion).
I am sure it is a thought game. There are also large yard bags, that are really large you can buy which will work as well and may be easier to do actually. A little research and thinking here will help a lot. The other is I saw you removed a lot of the bark from the logs, but left a lot as well This is a source of rot as the bark holds in moisture and allows for insects to hide. Also, once the log is debarked, charring it in flame will prevent rot where it contacts other materials. If you plan on rebuilding or starting a new construction, these points may help.

mike jastram wrote:The world's most complex debris shelter is nearly complete!

I'm new to this whole forum thing. But was wondering if you could answer some questions? 1st what was your rough end cost too build? 2nd is this a design that can be obtained through a source? If so is it expandable? I'm just asking because I acquired come land and really like this design but need something family size. Thank you for reading.

Thanks for posting, Kurt, if no one wrote back to you, the basic design is on Paul's website richsoil.com, and if you want more multi-room options that have been time-tested, Mike Oehler's $50 and Up Underground House book is really good.  It's on this site.  Hope you see this message and please give an update on how your project went, we can all learn from it!  

Kurt Riemer wrote:

mike jastram wrote:The world's most complex debris shelter is nearly complete!

I'm new to this whole forum thing. But was wondering if you could answer some questions? 1st what was your rough end cost too build? 2nd is this a design that can be obtained through a source? If so is it expandable? I'm just asking because I acquired come land and really like this design but need something family size. Thank you for reading.