David Haight

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since Mar 26, 2014
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Recent posts by David Haight

Any issues with rodents wanting to move into the nice warm space?
I wonder how well a thermal differential powered reverse siphon would do to both store excess greenhouse heat as heat, and also to do useful work to raise a small volume of water. Here is an example from youtube showing the concepts in action. He does use a fresnel lens to increase the heating  and decrease the cycle time, but if you did not care about how long it took (one daily cycle), I do not think the fresnel lens would be absolutely necessary. Then, just scale up until you get the volume you need lifted per day.

Another issue of applying this to aquaponics would be clogging or fouling of the check valves. Maybe need to combine with the "water teeter totter" idea given above to have some very clean water in the thermally powered reverse siphon side, and the "dirty" aquaponics water on the other side.

Again, this will probably not meet active oxygenation needs of any kind of serious stocking rate of fish. Though this may be enough to "passively" fill kratky buckets, make a very low flow NFT technique, keep duckweed tanks topped off, etc. But, all these tanks and flowing pipes and surface area will bring up the DO of your water a little bit as a side benefit. Picking fish species that can handle low DO is probably the best design choice.

This would probably pair better with vermiponics, which is where I think I am going next after this year's aquaponics experiments here anyway.
1 year ago
Love the topic and your documentation of it.

What about some annual and/or perennial sunflower around the water lenz cones, with the grasses? The sunflowers should be able to tap root into the soil, sun and wind reduction once they get up, grow in place some great mulch, withstand a few days of having their feet wet, add fungal habitat, etc.
2 years ago
Are you wanting/needing to stay in California? If you would consider Colorado, we should talk about the opportunities available here.

- DH
2 years 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?
2 years ago
I petted my puppy, who is still shedding like crazy. Now I am feeling like Franz Fur'dinhand....
2 years 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?
2 years 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"
2 years 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.
2 years 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
2 years ago