Devious Experiments with a Truly Passive Greenhouse - full movie

I give this movie 10 out of 10 Acorns.

As a kickstarter backer it fulfilled what I wanted the movie to be. Round wood work was amazing and showing how deep the pipes are was really cool. My hat is off to everyone who worked on this greenhouse.  As someone who was in on a few of the zoom meets to get updates on the greenhouse it is cool to see it come together as a movie. As a person with no round wood experience I was able to understand what was going to be built. When I showed this to my family, common phrases were “wow”, “holy cow” ,”what is ____?”.

One small critique.

If you are going to watch this movie with friends, family etc. And they do not know what a Wofati is and have not heard of Mike Oehler. Please take  a little time and tell them about Wofati and Mike Oehler’s work. I was watching the movie with my family and had to explain a few things but it was no big deal.

The greenhouse exists!  The movie is great!  I have seen both, and I can vouch.

We owe a huge debt of gratitude to all our kickstarter supporters for making this vision a reality.

A special shout-out to our producers for the film, permanantly memorialized in the greenhouse timberframe in wood-burnt glory!


(image source: Dez Choi's BRK)

Josiah wears much nicer greasin' clothes than most machine maintenance folks I know . . .

Hi. I am unable to open the video after I payed it. I think I made some mistake. what should I do now?

marcin dop wrote:Hi. I am unable to open the video after I payed it. I think I made some mistake. what should I do now?

Can you tell me more?  Can you see the movie with the play button?

Any update on how it performed in the summertime/fall (maintaining cool) about 180 days after the interior low temperature of March 14?

Joshua Myrvaagnes wrote:Any update on how it performed in the summertime/fall (maintaining cool) about 180 days after the interior low temperature of March 14?

We need more boots in the bootcamp.  Many things did not get done this last winter.  

Thanks Paul.  

Is it being used currently with anyone's greywater, or would it be the bootcamp's greywater that would supply it?

This might be a good inspiration for people to join the bootcamp.

There's also the question of what could be grown in this greenhouse now that it's here...even if that isn't its purpose, it can win over taste buds and stomachs to permaculture.  

Rambutan, lychee, longin, soursop, mango, banana, orange, pineapple, avocado, coconut?  tilapia, eels? do these need a really hot climate to thrive, or simply to be free of frost long enough to get big?  Apparently the big fruit-growing region of Vietnam ranges from about 50-85 degrees if my memory serves, not in the high nineties and hundreds as I'd assumed.  

I'm going to leave your questions here in case there are people here that have these answers.

This was so, so cool to watch. The joinery was well above my level of building knowledge, but it's so impressive. I'm always interested to learn about passive methods to keep heat in. Here in socal, my dirt is cooler than my air, so I'm thinking of adding thermal mass to my little greenhouse with water tanks that I can drain and fill in different parts of the year.

Joshua Myrvaagnes wrote:Thanks Paul.  

Is it being used currently with anyone's greywater, or would it be the bootcamp's greywater that would supply it?

This might be a good inspiration for people to join the bootcamp.

There's also the question of what could be grown in this greenhouse now that it's here...even if that isn't its purpose, it can win over taste buds and stomachs to permaculture.  

Rambutan, lychee, longin, soursop, mango, banana, orange, pineapple, avocado, coconut?  tilapia, eels? do these need a really hot climate to thrive, or simply to be free of frost long enough to get big?  Apparently the big fruit-growing region of Vietnam ranges from about 50-85 degrees if my memory serves, not in the high nineties and hundreds as I'd assumed.  

I can answer a couple of those. Mango doesn't like frost even when it's several years old, though it does get somewhat more tolerant with age. The cultivars of banana I grow (dwarf namwah, dwarf orinoco, and blue java), which are supposed to be a bit more frost tolerant than most, lose all leaves below 32 degrees F but didn't die-- leaves grow back in spring, and two of them fruited heavily this summer. The fruit is not ripe yet, and I have them wrapped in incandescent Christmas lights powered by a $20 greenhouse controller that kicks on under 40 degrees. But bananas only fruit once and then you cut them down. The pups (baby plants growing from the same root system) will then get more sunlight and grow to give you your next crop. So you can't just protect the banana plants while they're young and then continue to get fruit. Also, depending on your setup, they're often too tall to fit in the greenhouse-- my dwarf plants are about 8 feet tall. The fruit takes a long time to mature as well. From what I can tell, oranges are more frost tolerant than other citrus. We definitely get below 32, and my orange tree is thriving. Coconut I'm told does need to be warm, and you can't really fudge it. Avocado develops significantly better cold tolerance after the first year or two. Pineapple I'm told will tolerate frost without protection. Something I didn't realize until moving into a hot climate is that almost nothing actually wants to be over 90 degrees-- even your tropical plants would prefer 80 or often even 70. However, they can tolerate hot days better than they can tolerate cold nights. There may be a few exceptions, like plumeria cuttings will not propagate unless you keep them really, really warm.

paul wheaton wrote:When the pipes were not there:   weeks of a rock solid steady 46.2 degrees.  

And then we added the pipes:  no change.

And then we added the reflectors:  now we see change.

When we first started tracking we saw this



By the time january rolled around, we leveled off at 48.5.  Then, through the spring, the temps dropped a bit.

Two weeks ago Stephen grabbed the current temps and saw 52.9!  Maybe in january we will hit 54!


This means that the greenhouse is getting 2 degrees warmer each year!

Annualized Thermal Inertia is working!

Stephen is now setting up more tracking thermometers.  We will have more detailed data in a month.

paul wheaton wrote:This means that the greenhouse is getting 2 degrees warmer each year!

Annualized Thermal Inertia is working!

I guess I thought there would be a few hundred responses to this.  To me, this is pretty huge.  When the greenhouse is ten years old, the stored temp at the bottom of the thermal wells could be something near 65.  So if we have a cold night, 50 degree air will drop to the bottom and 65 degree air will rise up.  

All without fans, electricity, solar panels, or any work from anybody.  

This leads into ideas about adding a solarium onto a wofati home.  Only then the whole idea can be further optimized with window quilts.  

paul wheaton wrote:To me, this is pretty huge.

It is.  The problem is it takes a very long time to demonstrate, to prove convincingly.

Not to ask too much, but I'd be interested in a graph tracking the daily well temperature, and average outdoor air temperature, over a 2 year period.  That could answer many questions and objections, like:

Is the current temperature an anomaly caused by something other than the tubes & reflectors?
Does the well temperature drop during the winter?
Does the well temperature curve decelerate and approach a limit?
If the greenhouse temperature appears to be increasing without approaching a limit, does something need to be done to keep it within a reasonable range?

It would be very interesting to integrate this into a house.

I walked past you at the Modern Homesteading Conference, and realized you are very tall. :)

Thanks for all you're doing here.

Paul -

I, for one, think this is absolutely a breakthrough.

Oehler's greenhouse designs are passive, but made no explicit attempt to annualize the gains made during the warm months.  Pretty much everyone who is explicitly trying to annualize thermal gains - John Hait, Don Stephens, the "Greenhouse in the Snow" guy, Thorsten Chlupp, the Drake's Landing crew - is using some active form of heat mover, whether blowers (with or without condensation of atmospheric humidity to exploit latent heat transfer), pumps, sand batteries, etc.  Even if these heat mover devices are run with a solar array, it's still something extra to be maintained.  Even if it's only moveable insulation curtains or panels to prevent overnight heat loss, that's still something that either needs to be done (twice daily, mostly) or can break at an inopportune moment (not an exclusive OR!).  The sad tale of Drake's Landing is a cautionary example.

On the other hand, your version is more like a sundial than a grandfather clock.  Not much to break (comparatively speaking) - it just sits there and works.

I am very interested in what you are doing with this structure.  But I don't think I have anything particularly insightful or constructive to add to the conversation, so I'll continue to watch you log and report the successful results, until I am ready to start my build.  I'll be happy to follow the path you've blazed.

Having a structure which will passively maintain a livable temperature - whether for plants or humans, maybe both - without needing exogenous energy inputs, requiring regular manual tinkering, or relying on fussy electro-mechanical systems, is not to be underestimated.

Thank you.

Bravo!

I have also been sitting back and watching and reading the updates as they come.  Keep on the good track of tweaking, testing and recording!  I think that most folks tend to have "little" spare time and only want to pursue something that has been "proven" to work.  I think this is super awesome to achieve though and would love to trial something like this at some point in Alaska.

For more testing and more projects, please support the BEL https://permies.com/bel

I am thinking it could be time to record a youtube vid to talk about this.

Tim Blackk wrote:
Not to ask too much, but I'd be interested in a graph tracking the daily well temperature, and average outdoor air temperature, over a 2 year period.  That could answer many questions and objections...

Yes, it would be really nice to have that data. Unfortunately, it seems there aren't enough folks up there for all the current projects.

Maybe if the people in the bootcamp would get some nice incentives, there would be more of them (people in the bootcamp) and the temps in the greenhouse would be tested more rigorously.

That being said, we could all chip in and support the boots.

https://permies.com/BEL

Something of an aside to the main subject at hand, but worth considering I think:

With the demonstrated success of the "reflectorized" heat moving pipes, this design element might be fairly easily incorporated into existing conventional homes to help annualize summer thermal gains.  Augering deep holes, inserting sections of casing, adding the smaller pipes and running them to somewhere sun exposed (possibly insulated with pipe wrap for part or all of the run) and adding the reflector troughs - this all seems like it might be implemented at fairly reasonable cost.  Just spit-balling, but I'm thinking cheaper than installing a conventional wood stove (just capital expenditures, assuming DIY, so no labor outlay).

As a point of price comparison, I installed a $200 Craigslist wood stove (it's older, but is a sort-of bell stove, reminiscent of some of the masonry heater designs, just in welded plate steel) for my dad a couple of years ago (to help mitigate the rising cost of natural gas following disturbance to the supply in Europe, which had worldwide knock-on effects on pricing), and I'm pretty sure I had well over $200 into the installation cost, using a fair bit of scrounged materials (e.g. a short length of insulated triple wall, leftover stove cement and gasket rope, self tapping screws from another project, etc.).  This was into an existing, clay lined brick chimney, but I had to punch a new hole into the liner.  I don't think it could have been accomplished much more cheaply.  On the other hand, he has heated his house for two years running for about $100 per season in firewood in a fairly wintry climate (typically we're in the neighborhood of 4000 degree days, if I recall correctly - Edit: just checked, and last winter was 7300 with a mild winter. so I was way off).  With a proper rocket mass heater, it probably would have been no more than 1/5 of this wood usage, but would have required engineering substantial floor reinforcement, and would have been less immediately available.  And might have required a good deal of operator retraining, too.  The stove was providentially available at the right price and at the right time.  I still intend to build a brick bell for it, but haven't gotten there, yet.  Projects, projects...  On the other end of the DIY price spectrum, I have almost $1000 in fabricated chimney parts to install a wood stove in our house.  The stove that will go in is an older Hearthstone, with secondary air, but no catalyst, acquired used from a friend for $1500.  Eventually, I hope to install a mass heater (I am eyeing up G. E. Asp's contraflow heater design from the late 1930s, which is very like a batchbox rocket, but more aesthetically matched to the architecture of our 1890s house), but this will, again, require substantial engineering of a masonry plinth to support the thermal mass, whereas the soapstone stove can be installed with alacrity for nearly immediate use.

Could someone DIY a ground source heat exchanger setup similar to the wofati's into an existing house for $2500?  Probably so.  Worst case, do some now, as it can be afforded, and do more later from the cost savings as they accrue.

I have an expanding bucket auger for hand boring holes (also acquired very cheaply from a second hand store, so that I can auger an initial 3 or 4 foot deep hole when I eventually pound in a sand point for a pitcher pump - pipe sections are nominally 5 feet long).  I have seen a YT video of a fellow who used one of these bucket augers to punch a deepish bore hole (25 feet, maybe?) to provide water for his bees, by cutting off the T-handle, and using two sizes of telescoping square steel tubing to make removable extension sections (Edit: see here - https://www.youtube.com/watch?v=-nN8-Aso5b4).  The larger size of tubing made the couplers, while the smaller size was the actual extensions, with quick-pins to join the sections.  As the hole becomes deeper, sections must be added and removed for each round trip.  In the free and open air, with unlimited overhead clearance, sections only need to be added as the hole becomes deeper, unless the total length becomes too unwieldy when pulling up the filled-up auger head to empty it.  But, with floor or ceiling joists just overhead, each trip to and from the bottom of the hole would require adding and removing the sections.  I think he welded the coupler sleeves to the extensions, but bolts, pins or screws could also work.  I haven't made the conversion, following his lead, because I don't need it (yet!), but I have eyed up tubing costs.  Depending on the available overhead clearance (probably somewhere between 6 and 8 feet, with the lower value in a cellar, and the higher value in a newer basement or a slab-on-grade first floor), the extensions could be sized accordingly.  Similarly, the casings to line the augered holes could be glued/screwed together in sections of appropriate length to match the available clearance.

One additional modification which could be made to an adjustable bucket auger is to add a removable center pilot (length of plastic pipe, perhaps), which would act as a guide if the full diameter of the holes were cut in two passes.  The bucket auger could be set to the smallest diameter (or whatever matches the pilot) and run down to full depth without the pilot.  Then the auger could be adjusted to the larger diameter, the pilot fitted to the auger head, and the hole could be reamed to the full diameter.  The pilot would just ride along in the existing smaller diameter hole.  This would reduce the required torque and cutting loads imposed by a difficult or consolidated soil.  Reaming holes to a larger diameter is apparently a fairly common operation in well drilling.  I haven't tried this, and don't have a prototype to show, but it has been kicking around in the back of my head.

Retrofitting existing structures to take advantage of some of these innovations (e.g. the gravel bed rocket mass heater in the Fisher Price house) is very important, I think.