Growing up, my parents didn’t ‘believe’ in air conditioning. (That should likely be read as 'thought spending money for cool air was wasteful giving our area only had high temperatures for maybe two months a year.) As a result, I often escaped down to the basement with a book during the worst of summer heat waves. Yeah, it was somewhat damp and not comfortably decorated/furnished for lounging, but it was generally in the 60s, so great for cooling off.
OTOH, we all know there’s a whole lot of the earth that is way, way hotter. Like molten rock and even hotter. So theoretically you could dig another, deeper basement, where the air would just stay at, say, 75F all the time, where you could lounge around comfortably even if your heating system goes out in the middle of a cold snap.
So… how deep would this cellar have to be? I’m sure it wouldn’t be cheap to build, but would that depth present any unsurmountable obstacles? Like the pressure at that depth would crush the cellar out of existence no matter what construction materials you used to build it? Or the air wouldn’t be suitable for breathing or whatever?
Depending on ground conditions the temperature from 30ft. below the surface down to several hundred feet below the surface remains between 50°F and 60°F. Somewhere between 500 and 1000 ft. down it begins to get hotter.
Don’t have to make it that deep. The TauTona mine in South Africa is 2.4 miles deep and reaches 140F at the bottom.
It’s generally stable, although rock burst can be a problem in mines, especially when they’re this deep.
Of course the depth requirement for being hot changes if there’s any geothermal activity in the area. At that point, a conventional single-story basement can be too hot to exist in.
The phrase geothermal heating has two different meanings. As originally intended, it meant digging a hole sufficiently deep that could run a pipe full of water and bring up heat from underground. That had to be over 500 feet and deeper was better.
The current meaning of geothermal involves heat pumps and doesn’t have to be deep at all. You pump heat in (against a gradient) during the summer and out during the winter.
Not always. Many geothermal heating projects used to be in places where the gradient was a lot shallower, like places with hot springs or geysers - volcanoes, even. So one didn’t have to go down very far at all to hit boiling temps.
My understanding is that the near-surface (i.e. the first few dozen/hundred feet down) temperature is roughly equal to the annual mean air temperature above ground. So, excepting geothermally active areas like hot sprints, Iceland, etc., your underground temperatures in Siberia, Norway, or Alaska are going to be starting out much lower than in Ecuador, Nigeria, or Kenya. See this groundwater temperature map for instance. It’s not exactly the same thing, but it should be strongly correlated.
This may be a bit early in a FC question, but I have enjoyed bathing in the confluence of a volcanic powered, extremly hot river with a river off the same mountain which was cold (I mean, given “cold” at that area was 40° air temperature ( 104F ), I did not measure it)
Each miniture rapid had hot and cold bits mixing in.
The “hot” river was at temperatures around 80° ( 179° F) again an estimate.
I climbed Mt Salak, near Bogor in Western Java, Indonesia and had the extraordinary experience of watching tourists, mostly internal, boiling eggs in the hot, sulphurous pools at the top. And then eating them.
I mean, the place smells like rotten egg. I’m not going to critique the culture, just their sense of smell.
Yes, but depending on the soil and climate you probably don’t need to get more 15 ft. below the grade to keep a basement between 50 and 60 degrees steadily. Locate a furnace or small heater in that basement and you could be in the 70s in winter time, and comfortably cooler in the summer. It just takes a while to get to the point where the ground temperature reaches the 70s.
When my parents build their farmhouse in the early Fifties, the builders dug down only four feet for the basement, because of the high groundwater level. Once the basement walls were constructed, Dad hauled in dirt to create an artificial ‘hill’ surrounding the house. We didn’t have a/c either when I was a kid, but I remember the basement as being pleasantly cool in the hot Kansas summers. My siblings and I slept down there, and I have no memories of it being too hot to sleep.
Yikes. At ten feet per floor, that would mean hiking down (then up) fifty to a hundred flights of stairs. And later posts were talking in miles…I think I’ll table that plan.
Though…the exercise of that many steps would no doubt work to warm me up internally quite well.
Sorta like the old joke about firewood: It warms you several times. Once to chop, once to schlep, once to stack, and once to burn. Or something like that.
That’s a different question. Geothermal/ground-source heat pumps are using the ground which is at the average annual air temperature, normally in that 40°F to 60°F range. They’re not utilizing that temperature ground directly to heat and cool, they’re using it as a more stable heat sink than the air. The depth of the wells is only a function of how much capacity you want the system to have and how many wells you want to dig. More shallower wells, or a horizontal loop, is the same as fewer deeper wells.
