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David Haight

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since Mar 26, 2014
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Recent posts by David Haight

Are you wanting/needing to stay in California? If you would consider Colorado, we should talk about the opportunities available here.

- DH
1 week ago

Josiah Kobernik wrote:I calculated that the total weight of the roof with three feet of soil soaking wet above the membrane is 12,660 lbs.
Each of the 8, 8 inch posts can support more than 22,000 lbs. So that's cool.

13x safety factor!?! Hopefully it's not an unlucky number.

What is the purlin size needed to transfer loads laterally to the posts?
5 months ago
I petted my puppy, who is still shedding like crazy. Now I am feeling like Franz Fur'dinhand....
5 months ago

Josiah Kobernik wrote:here are the drawings that will be the basis for Kyle's new 3D model.

Looking forward to seeing that model, what the engineering numbers indicate the log sizes need to be, etc. When is it due? When are you all trying to start construction?
5 months ago
An audio engineer swore that he could hear a very deep male voice speaking to him in a random selection of all sound frequencies. He called it "Barry White Noise"
5 months ago

Josiah Kobernik wrote:In critique of the strategy of capping things off for later testing, I will relay two things that Paul has told me.

thing one, instead of testing each innovation independently with controls, paul likes to heap ten or more innovations into one experiment and then if the experiment is successful, you can successively divide the innovations in half to sort for relative influence.

thing two, the annualized thermal inertia aspect of wofati structures takes years to test. It may take 2 or more years for the mass to be fully charged and operating in semi-stable seasonal temperature fluctuations. So capping and uncapping earth tubes within the first 5 years muddies the results of the thermal inertia. That being said, If it takes several years for the greenhouse to start working, then it's not very attractive as a design solution.

I agree that changing too many things too fast is not helpful for comprehension, invites instability through over-management, etc. Having the discipline to not touch the controls until a certain point is just as hard as having the discipline to go check on it every day. Hence why I think having defined trigger points for intervention by someone in the group of observers / managers / recorders of this thing makes a lot of sense...

What's the hoped for lifespan of the building beyond the initial annualized thermal inertia testing? 50 years? 100? more? Climate could do funky things in that time frame for 100 different reasons. For our greenhouse here, I will try to plan in enough passive, active, etc buffer for things to change say +2 USDA zones and -2 zones in climate. I will be watching with interest to see what you all decide for this one.
5 months ago

Josiah Kobernik wrote:I think a thesis is a good idea. here is my first crack at it.

"A combination of:

    An 8 foot deep cold sink

    Two well casings extending 19 feet deep below the cold sink fitted with passive air circulation units

    Dry earth thermal mass on the roof, as well as the North, East, and West walls that is disconnected from surrounding soil by a polyethylene membrane “umbrella”

    Inflow of household greywater at or above room temperature

    A south facing glass wall measuring 10 feet by 5.5 feet, sloped perpendicular to the angle of the sun at solar noon on February 1st

Will be sufficient to keep a greenhouse with interior dimensions of 10 feet by 9.5 feet above 50 degrees and below 92 degrees year-round in Western Montana at an elevation of 3200 feet above sea level."

Excellently specific! The map is not the territory and the measurements are not the thing measured... BUT... having facts and figures  and temperature numbers does help those of us who are not in your specific spot adapt your design to our context, compare why it worked in one context and not another, etc.

List of what counts as failure, negative result, type 1 error, etc next?

And would you please verify the time for the next zoom meeting today? Thanks
5 months ago
Sorry for having to go quiet at the end of the meeting, I was not able to keep the coughing at bay... Here's some more detailed reactions, ideas, ravings, and possible gibberish...

Bathtubs: I like the idea of separating moist growing soil from structural and insulative soil. I am a bit worried about the bottom of the bathtubs going anerobic. Consider a full blown wicking bed setup in the bathtubs? Also, the outside of the bathtub may have "sweaty toilet" syndrome in the warm and humid period of the year, so having a plan to harvest that condensation would be good. Also, harvesting condensation from the windows straight into the wicking bed reservoir would be passively awesome.

Gravel around posts: Nailed it. They do the same thing on fence posts here in wetter clay soils and even though they get rained on periodically, the bottom of the posts rot at least 2-3x slower to non-gravel protected ones...

Earth tubes / cooling tubes / ventilation tubes: Yes, the more the merrier. As Reximus Prime said in the meeting chat, you can always cap them off initially or to reduce the number of variables that you are testing. They are hard to retrofit in later, but easy to install in the initial build. If nothing else, they are cheap insurance against some of the potential achilles heels we have been discussing. Folks living in earthships do cover/cap these in the winter to not draw cold air through the berm or into the space. Vent up high to create stack effect to pull new air into the space through the ventilation tube is a must.

Instead of building a greeenhouse v0.7 then 0.8 then 0.9 ... I think it makes a lot of sense to be able to use this structure to test various configurations from one build cost. Could multiple thermal boreholes be drilled, one under the cold sink and one up front? Earth contact tubing between them that could be opened or closed?

That being said, I think it would be smart to come up with a thesis statement for this one to guide the initial setup of what is opened vs closed off (i.e. "a single thermal borehole and destratification pipe is enough to heat and cool an earth sheltered greenhouse in Montana"), a set of potential problems and negative results (humidity, mold, low CO2 levels, overheat, etc), potential mitigation steps (like opening the upper vent, opening the upward sloping ventilation tube, etc), and trigger points for each mitigation (interior reaches 99F the first time, mold is sighted on plants, etc). Then, the final design for this build can have these mitigation elements in place or at least the structure where the mitigation will go already installed...
5 months ago
I'm not too worried about a long term toilet paper shortage, because I know how to take it day bidet.
5 months ago
A priest, a minister, and a rabbit walk into a bar. The rabbit says, "I think I am a typo".
5 months ago