I didn't update much lately. We are simply waiting for developers to swallow up our very old apartment and buy us out. It could happen any day. Until then, I'm just in material collection mode. This spring I was very busy teaching. I've wanted to learn EnergyPlus in more detail. This will help us to understand the energy situation and what we can expect and how big we need to make the heat storage.
Last winter, at least the first half we lived in an old house and better understood the energy situation. The building is so old that the only insulation is logs with mud plaster on both sides. The building does not have a water line coming into the house, so I made a bottle shower stall with hanging tanks, which drains into the yard. That worked until late November. One night we were not home and did not stay home and the water in the cold water tank froze and that was it for the whole winter. Coal/wood stoves are powerful at a low price, but they are a burden to maintain everyday, when you have to collect/buy coal/wood/paper/cardboard and watch the fire as it starts out. The wall couldn't be more than R-7 or R-10 at best. The ceiling is concrete with lots of dirt up there. It felt like most of the heat loss was through a side wall that had mud knocked off on the outside and under the floor. The house has a pseudo-foundation of raised stones and a wooden floor, so heat just seemed to escape under the floor.
It took me a while to understand the ground situation. Nobody really publishes max frost depth on the web around here. Some mining .pdf literature suggested a max frost depth of 2 meters. Later I found other research on permafrost in Mongolia. Basically in the southern half of Mongolia there is no permafrost and a max frost depth of 1,2 or 3 meters. Then as you go north there is permafrost. Around Ulaanbaatar as best I could tell the permafrost is 5-15 meters deep, except where influenced by human development and perhaps topography. The permafrost is -0.4 to -0.1C or close to that. Roughly speaking that means that from a depth of 15 meters and deeper that it is above freezing as warmer as you approach the center of the earth. Unfortunately, the earth temperature is not +58F as earthship vol. 1 suggests. That is the true max frost depth: 15 meters. Above 5 meters it may get above freezing and be influenced by the seasonal weather.
This has several implications. If a thermal wrap of insulation is made around the perimeter of the house, that's an improvement, but 5 meters down (below the thermal wrap) it will always be freezing or close to it. Heat will always transfer in winter from the warmer living space to permafrost area below. Therefore floor insulation is absolutely necessary (unless the thermal wrap was about 15 meters deep or possibly more).
It also means that a cistern cannot be placed below a frost line, but it and all its components must be enclosed in excessive insulation in a freezing environment that can get below -40F. They do sell cisterns in Mongolia and my wife knew somebody that had one in the ground and it worked. Water just has to be +1C or above and you're OK. Here 80% of the precipitation falls during June-September, so the cistern has to be so big to hold an entire year's worth of water, so I am planning to do multiple chamber connected tire cisterns with lots of insulation so the water will never freeze, even if that means an insulated cap after November.
Almost no one owns a snow shovel in Mongolia, because it doesn't snow enough in winter. It does snow. Somebody was suggesting to melt the snow on the roof like the global model to maximize water collection. The problem is even if I melt it on the roof, it will freeze in the gutter. Even if I melted that, it would freeze in the silt catch. In Mongolia ice sublimates directly into the air it is so dry, so it is better to make a large(r) roof and collect a little more of the summer precipitation and just cap the cistern from about late October. Another issue is letting pressure relieve in winter, since even a tiny hole might lead to freezing. I'll just have to deal with that as we go. We can always open it periodically or experiment with tiny holes.
I learned one thing from the bottle wall shower stall. That shower stall has an opening from the shower drain to the hose to outdoors. I expected that water would make it outside, but freeze as it sat outside in the hose. What happened in real life was that cold air from outside entered through the hose and cooled the metal drain to below freezing. When any water touched the drain, the water froze in the drain. That water stayed freezing until probably late March. I disconnected the hose from outside; I poured in hot water in the drain, but the concrete shower stall remained pretty cold with its thermal mass and being fairly close to a cold wall. In the same wall the problem could be metal components in the water line, not the actual cistern.
Another thing I learned from that experience is: What if we had to leave the house for a week or a month in winter and didn't want to make somebody live there for us? The water system has to remain frost-free. We need to have assurance through energy modeling that the house inside would somehow stay above freezing (even +1C might be enough) even without running artificial heating. OK, we perhaps have to insulate most if not all the piping. The cistern and the incoming line must be frost free on their own. OK, maybe if we knew we were leaving for days we could perhaps drain the water system.
Another thing is that we are planning to implement the ZED style multiple layers of insulated curtains (or shutters) on computer control to open around sunrise and close around sunset. (Here, it's so dry and consistently sunny that we don't need to be concerned about cloudy days. Even in winter 33% of avg. solar gain in January was like an minimum value over a long period, unlike NYC which was 3% of avg. one day.) If we have the "third greenhouse" buffer zone on front as well as the 1st greenhouse glass in front of the living space, then there is a good chance it will never be below freezing in the house. All the plumbing will be in the center living space area.
The bottom line is insulation and lots of it. Then with enough insulation around the cistern, we can keep its bottom well above the floor level in the berm. This means that we need to use high density floor insulation under the living space and the cistern. In Mongolia the cost of rigid insulation is 1/6 of the price in the US. Insulation works. Without it here one would have to rely on a pan of water to wash yourself. If we have adequate insulation, then things may not freeze if everything is properly managed.
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