Richard Grevers

Chad Sentman wrote:
I would not put the strawbale into any sort of receptacle that would prevent excess liquid from draining out onto the soil.

So drain holes in the bottom then! Thinking of the bin as easy to remove, empty and clean.

We are looking at building a two-bin composting loo (separate seats for pee and poo) for our family of 4 (2M, 2F). I've used a haybale urinal at short permie events, but wonder if anyone has ever used one longer term.
Our plan is to use small (80 litre) wheelie bins (that would probably only hold half a bale), and just peeing onto the surface.
Any thoughts on how that would go odour-wise and how long the bale would last? We would vent the bin.

I should add some background info: We've been off-gridding for six years, but in a house we don't own. We are now planning our own build nearby.
Existing system is relatively small, solar plus hydro, 450 AH storage, with both panels and batteries renewed in the time we've been there. We have a Gram fridge (6 efficiency stars) but not enough power for the matching freezer, which lives in town. We live in temperate rainforest, so water is not a problem and is all gravity fed. But we can go for a week without a sunny day in winter, and the water feed can be knocked out by flooding.

In our new build we will have much more storage, and probably a solar wind combo now that there are good VAWTs available from China. (Getting a 50mm water feed across the road will not be cheap). We will probably run 24v generation and storage rather than 12V

It is mostly events while we are not at home that we are concerned about.

Wondering if anyone has considered, designed or built an off-grid electric system which has separate storage for essential and nonessential uses.
The idea being to maximise the uptime of essential loads. These might include refrigerator, freezer, and water filtration (if UV is used). These would have a dedicated battery bank designed to cope with 3-4 days of no generation. It would provide protection against stupid mistakes such as leaving lights on
Nonessential loads is basically everything else: Lights, phone & laptop charging, small kitchen appliances, electric blankets (yes, we've found we have sufficient power for 30-minute bed warm-up, loving it!) entertainment etc.
The essentials battery bank would have first priority for being charged. It would also be able to draw from the nonessentials battery bank (possibly via a step-up if the NE voltage is lower than the E, obviously limited to cut off at minimum recommended voltage (10.5V / 21V)
Could this be managed with the likes of a Raspberry Pi and some relays?
Also important is an inverter which can automatically turn itself on again if voltage has recovered after a low-voltage trip - does such a thing exist?

Christopher Steen wrote:There is a place for LV DC wiring, including lighting, but I don't see advantages using it in a new residence these days with abundant cheap AC LED fixtures and bulbs, including even low budget off grid electrical systems.

I see an advantage (in the off-grid situation) - inverters trip out, and unless they are very fancy and expensive, they don't self-reset. Having your lights still working independently when the inverter trips is definitely a good thing™

I've also been looking at this problem for an off-grid property with a very small inverter. LED does away with the need for heavy duty and short-as-possible cable runs for 12V lighting systems.
Here in New Zealand the specialist lighting shops are full of LED fittings, but they are all designed for mains (240VAC) operation with built in transformers and rectifiers.
The only DC fittings I have found are from caravan and yacht suppliers, and hence tend to be expensive (the old saw about a yacht being a hole in the water into which you pour money).
The other problem with them is that caravans and boats tend to have low ceilings - so most of these fittings have switches on the side of the fitting, which will be out of reach in our house application.
Yes we can have MR16 bases dangling on wires, but we'd prefer something a bit more elegant!  And otherwise unconstrained LED spots do occasionally fall out of those bases when hung vertically.

Thanks for the replies so far. With our council, it seems that they are more lenient with future experimental buildings if you first have something comparatively conventional on site. Proviso of living temporarily means slight upgrades to posts, and not allowed a "full" kitchen.
So we're currently getting quotes from farm shed suppliers for a  steel-clad post & beam shed (around 50 sq m) - kitset is about $NZ6000 sans floor. I'm thinking along the lines of a poured straw clay or cement-based insulating wall with small plastic bottles built within.
Also looking at underfloor bladder water storage, although that is dearer than a plastic tank.

(ln response to a now removed question as to why concrete slabs failed and small buildings got airborne)

Case one, on a more level area, the primary cause was insufficient ground clearance (and grassed soil tends to build up over the years, making it worse). Result was rising damp in the outer walls. Case 2, the house we currently are in, the guy building it in 1981 had two sheets of polythene to go under the concrete. He lapped them by a foot or so and gaffer taped it. Water pressure from the slooe above eventually found a way through resulting in a patch where any floor covering quickly rots. Yes it can be done right, but not on a budget.

The shed was a couple of learning processes. 1) complying with "relocatable" requirement to avoid need for a building permit doesn't mean you can't have any attachment to the ground. And 2) To avoid a monopitched roof acting as a lift-generating wing it needs to be pitched at 18 degrees or greater.

Edit: after sleeping on it, it has occurred to me that the solution for any high-mass earth-based structure (rammed earth, earthbag, earthship etc) is to create a raised platform under it. Roading mix from a quarry about 25km away is $15/m³ plus the cost of trucking it and compacting it. Minimising platform costs would dictate site location - more central on the section than we would otherwise like.

There is actually a long Wikipedia article on tin can walls (looking as though it belongs on appropedia instead), although on reading, i think they are actually referring to aluminium cans in many places.

https://en.m.wikipedia.org/wiki/Tin_can_wall

I've just been considering the idea of small PET soft drink bottles (we have a type about 6" tall) sat vertically with lids on in several rows, possibly with a sheet of plywood for each layer to sit on. What would be a good substance to put between them? (possibly poured with formwork)

...and we would probably present this to the council as a shed or workshop that we are going to live in for a couple of years while we plan a permanent house. And that probably means no space heating, because a fully permitted woodburner ends up at about $5000. So insulation will be critical. Oh, we are off grid for power, too.