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Modern Prefab House Gets AC Off Grid On A Tiny Solar System! With Tornado Proofing And Permaculture At Our Off Grid Modern Cabin.

Yes, you heard that right. We have outfitted the modern prefab house for AC despite being on a tiny solar system- four 210w panels. Yep folks, we run our entire HOUSE off the power of just 840 watts.

For years, we didn't even consider air conditioning at the modern off grid prefab house. Ok well fine we *considered* it, researched it, mused upon it, but never found anything we felt good about implementing.

Plus when it's super hot, you will find us at the bay! Air conditioning was never a huge priority for me, off grid, because my philosophy was, "Hot? Honeychile, sip some sweet tea and spend the hot afternoon at the lake!"
Solar cooking, mowing the lawn, all at once!
I'm working HARD!

This changed. Our daughter (and I) have alpha gal. Unfortunately, like many people who suffer it, alpha gal also triggered high histamine intolerance and mast cell issues in our child

You might think of high histamine intolerance being just a food issue, but it also a TEMPERATURE reaction. Hence, no extreme heat and cold.  So I wanted a PLAN for when it's 110 to keep our child safe.

In the end, I presented my strategy to Handsome Husband, who again did that special imperial German dismissive chortle he does so well when I present him with a great idea that makes me want to backhand him hard across the face. "NOOOOO it ezzzz not POSSIBLE, ve arrrr OFF GRID!"
Don't call me grumpy, I'm beautiful.
This is the look you get when you pluck my nerves.

But. There was a point last week where he was in SO much trouble for something else, that I suggested he not come home... without a small, energy efficient AC wall unit.

He came home... with an AC unit. I tersely told him to get out his oscillating saw and cut me some plywood to fit the small square window in the east, and to stick that AC in, stat. 

He did. It works. 

Off Grid Solar Notes On AC On A Small Solar System In An Energy Efficient Prefab:
Now WHEN the AC is running, I make sure to turn off the water pump / anything that's a big draw! I keep a careful eye on the battery bank to see if we need to run the generator at the end of the day if we run it! 

This AC unit is supposed to cool a 10x12 foot room.
It cools the entire 1,200sf modern prefab house.
Good work, boys. Oh by the way I have another job for you...
Just like in winter, when in extreme cold our tiny firebox on the cook stove heats the entire energy efficient prefab house, this little AC unit, which is only supposed to cool a small room, makes extremely hot days bearable (even cold!) in our off grid house.
We're cool, even in blazing heat, thanks to energy efficiency,
passive solar design, and the final kicker on those sweltering days: sparingly-used AC.

Here is Handsome Husband's synopsis:
"When we run the window AC unit we draw on average 350 Watts more than normal for a total loss in the low 500s. On a sunny day in early May we have a net effect of -4 amps of draw from the battery bank which at 24 volts is about 100 Watts so if we increase the capacity of the solar panels from the current 840 Watts then we will be able to offset the increased load from the window AC unit while continuing to recharge the battery."

Here are my own notes on using AC in an off grid prefab house that has super-small solar systems: 

(Side note: seriously people, why aren't y'all dressing for the seasons, even at work. Actually, especially at work as this is where you will spend the majority of your "high heat" time over the week.)
  • As usual, sleep with all the windows open
  • As the sun starts to heat everything in the morning, close the windows
  • When it starts to be uncomfortably hot, turn on the AC (in the small square east window of the great room) set to 78, energy saver. It says 78 but in an energy-efficient prefab house it feels like 70. I'm already fighting Handsome Husband who wants to set it to 76: "That's crazy, can't you see I have goosebumps?"
  • As soon as the temperature slips under 90 outside, turn off the AC, open up the windows and let the breeze in. 
  • If it's a super hot day in the mid to upper 90s and no relief in sight, feel free to run the AC with the generator so you don't stress your solar systems.
  • PASSIVE SOLAR NOTES: The casa ti is designed passive solar to work as is for most of the year BUT in extreme heat / sun feel free to hang strategic seasonal curtains or awnings!
The installation and testing of AC could not have come at a better time. Sweet spring suddenly switched from breezy and pleasant to summer temperatures in the mid-90s.

I watched our alpha gal high histamine intolerant child flush, and start dragging, weighed down with headaches as the heat rose. "It's okay," I soothed. "Let's just turn on the air conditioning awhile."

We only felt the "need" for AC in the blazing afternoons. But for a medically impaired child, the relief the AC provided was invaluable.

At the modern prefab house, we are also in tornado season.
Mid-April, EF-3 tornadoes touched down in nearby towns, with wind speeds of 150mph.
This is the third time we have ridden something out like this in the area in the past four years.

At the off grid modern prefab, we were not among the over 19,000 locally left without power.
Over 25 homes were demolished or severely damaged in nearby towns.

This time I didn't see a funnel clouds touching down from the sky. (Last time I did!)
But the pressure drop was insane. You could just feel our house turning into a pressure cooker!!!! Thankfully nothing happened aside from the crazy pressure barometric drop.
(At that point I tossed the teen in the bathtub!)

Here are some tornado safety tips, and here, off grid in our small footprint home, is what WE are doing:
  • Now you know a SIP house is structurally strong, so there's that!
    • From SIP School: "A structural insulated panel’s standalone strength, the fastening details, and the design of the structure itself all combine to create a safer building envelope.  Credit to both designers and engineers should not be discounted.  A 140 + mph wind event requires that all parties be at the top of their game. "
    • And this: "As  you see in this video, stick framing is incredibly vulnerable until the sheathing is properly nailed off.  A stick framed wall has no resistance to shear until the sheathing is nailed, making it vulnerable to collapse from wind or seismic loads.  When structural insulated panels (SIPS) are used as the framing method you have the full sheer strength available immediately as soon as the SIP is installed and nailed to the sill plate, top plate and adjacent panels.  Risk less when you build with SIPS."
    • And from an area that knows much about high wind, read about another SIP case study in Florida.
  • BUT if you are a mom like I, nothing is ever good enough. As we do not have a proper official storm shelter, I looked at the layout of the casa ti modern prefab house and determined the bathroom would be our "go to" place as it was in the center and had the least amount of windows.
  • The bathroom is clad with plywood. 
  • This is by no means an intentional storm shelter (FEMA details here), but an "on the fly" approach "for the meantime."
    This is a great picture because it shows:
    1. unclad SIP on the ceiling
    2. maple floorboards on exterior to the left
    3. thick plywood lining the bathroom
    4. and note the south wall of the bathroom
    is thus covered in maple

    • Here is a proper way to build a wood storm room, and from this we are adapting the bathroom as we can which is better than not having anything at all (and at least we're a SIP house!!!!)
    • And this article notes, "Above-ground safe rooms can be built in a basement, crawlspace, or on a slab. They can be constructed with standard building materials—though beefed up considerably. Basement lean-to rooms are built with 2x4 framing; each stud is doubled-up and the wall is sheathed with two layers of 3/4-inch plywood over a layer of 14-gauge steel sheathing.

      The main point of weakness is the door; the hinges and latch are the critical links. To secure the latch, FEMA says to use "3-locking pins, dead bolts, or slide bolts with min. 1-inch throw surface—mounted to astragal with #8 x 3-inch wood deck screws." (The 1x3 astragal is fastened to the double 2x4 framing with 3-inch deck screws)."
    • This article (click the pdf) goes into more detail on a wooden storm shelter!
So: we have a slab, we have a SIP house, we have a thick plywood-clad small room (bathroom) with one window and door.  But wait! Not only do we have a slab, a SIP house, a bathroom clad in plywood... but the EXTERIOR of the bathroom (walls shared with adjoining bedrooms and hallway) is... clad in THICK HORIZONTAL MAPLE BASKETBALL FLOORING nailed in!

Not only is it nailed in to the plywood, but the maple flooring interlocks vis tongue and groove, making it further strong and secure!!!
Exterior of bathroom's west wall (thus
the inside of the center bedroom).

Exterior of the bathroom's east wall is maple as well...
...and the north wall of the bathroom is 1. SIP and 2. further covered with plywood.

So to even get to the bathroom, a strong storm would have to FIRST penetrate the SIP. 
THEN it would have to penetrate the maple, then the plywood... and yes I'll be adding a steel door vs. the wood door we currently have, and cladding the plywood window cutout we have with steel.

And finally, we brace the window covering securely with simple metal bar holders found in any hardware store:

From USDA's Tornado Safe Rooms From Commodity Wood Products:
"Results indicate that a nailed and glued wall section constructed of three layers of 2 × 8 lumber and sheathed with 23/32-in. CDX plywood can consistently pass the impact test. "

Did we unknowingly create (a great start to) an efficient storm shelter? 
I think we did.
So if YOU are considering using plywood, and using horizontal boards to clad your SIP prefab house interior, think about these applications for 1. doing something you want to do anyway: clad the SIP without using drywall that 2. also strengthens a possible storm room ALL IN ONE STEP!

Permaculture At The Off Grid Modern Prefab:
We are again doing some excavating work on our property and would like to mention how USEFUL logs and brush are to improving your soil. So instead of making a humongous bonfire, use them for your garden! I highly recommend Sepp Holzer's Permaculture book not only for these raised beds but for its wealth of information on improving soil, and you can also read a little about his methods of raised beds here, and here.

Basically, we followed Sepp Holzer's methods and cut two trenches at 45ish degree angles on a slope.
Sleeping on the job!

Into that, we put in some rotting logs...

...then piled up brush on top of the logs...

...added a layer of topsoil... (upside down)
...then over it all dumped good soil we relocated from the bottom pasture.
Now we plant.

Permaculture notes: Y'all know we go to and fro and back and forth in summer. So I expect nothing less than to grow plenty of weeds these first years. HOWEVER I made sure to seed these hugelkulturs with plenty of things that are 1. perrennial or/and that we can 2. harvest in late summer / early fall after our sailing season of back-and-forth is over. That included swiss chard, onions, kale, asparagus, salsify, sorrel, and then annuals that take time like plenty of sweet potatoes, potatoes, beans, artichokes and peppers.
Two of these hugelkulturs were plenty.
See how high they are?!?

We continue with homestead projects: To our chicken run, we added a downspout and rain barrels (which also has wood & tool storage; the wood helps insulate the coop in winter, climbing roses & vines provide shade in summer) = even MORE functionality in one structure! Holzhausen in foreground. We have a few more barrels to add but it will be great for watering the garden. Note we put the rain barrels on a base to aid in gravity-fed water for the down-the-hill hugelkulturs.
This time of year I heavily rely on my SOLAR COOKER. It is especially useful for cooking potatoes, beans, slow cooking meat and vegetables... without using anything but the sun.
I have been really enjoying making all sorts of savory (and sometimes, sweet) pies in ceramics in the solar cooker. The crust is totally flaky, the pies, delicious. It is so important with a child who has medical food issues to present food that is colorful, nutritious, and even fun. These ceramic experiments do all three.
For this "pie" first I poured a "batter" that acted as pie crust in the bottom and seperately cooked the filling in the solar cooker. Then I poured the cooked filling onto the "crust" and guess what? It was SO flaky and delicious. I am omitting more traditional eggs to bind things together in these pies due to Teen 2's alpha-gal triggered high histamine intolerance, fyi.

White bean, onion, kale, and ground turkey soup.

Solar cooker is cookin' while the passive solar (with sparing AC) kept us cool!

Oh! I know my friends will be SO excited I can still make molded food despite alpha gal thanks to this vegan algae-based powder! YOUR DINNER PARTIES ARE SAVED! I just KNOW y'all are excited!!!

Reading Club:
Well, I guess we'll go back to work on more homestead projects, and in the meanwhile, have a great spring.

Cornbread thinks he's handsome.


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