# How deep would you need to go to create a naturally warm basement? **URL:** \ **Category:** Factual Questions\ **Created:** [January 10, 2024, 5:54pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907 "2024-01-10T17:54:50Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![StarvingButStrong](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/starvingbutstrong/32/335_2.png) [@StarvingButStrong](https://boards.straightdope.com/u/StarvingButStrong)\ **Post date:** [January 10, 2024, 5:54pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/1 "2024-01-10T17:54:50Z")
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? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [January 10, 2024, 6:06pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/2 "2024-01-10T18:06:44Z")
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. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 10, 2024, 6:39pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/3 "2024-01-10T18:39:03Z")
> [@StarvingButStrong](#): > > 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? 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. > **[TauTona Mine](https://en.wikipedia.org/wiki/TauTona_Mine)** > > The TauTona Mine or Western Deep No.3 Shaft, was a gold mine in South Africa. At approximately 3.9 kilometers (2.4 mi) deep, it was home to the world's second deepest mining operation, rivalled only by the Mponeng Gold Mine, but was closed in 2018. > The mine was one of the three Western Deep Levels mines of the West Wits gold field west of Johannesburg. The mine is near the town of Carletonville. TauTona neighbours the Mponeng and Savuka mines and they share processing abilities. All three were o... It’s generally stable, although rock burst can be a problem in mines, especially when they’re this deep. > **[Rock burst](https://en.wikipedia.org/wiki/Rock_burst)** > > A rock burst is a spontaneous, violent failure of rock that can occur in high-stress mines. Although mines may experience many mining-related seismic events, only the tremors associated with damage to accessible mine workings are classified as rock bursts. The opening of mine workings relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode, or trigger abrupt movement on nearby geological structures. Rock bursts are a serious hazard; in South Africa, th Ro... 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. ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [January 10, 2024, 6:44pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/4 "2024-01-10T18:44:48Z")
> [@TriPolar](#): > > Somewhere between 500 and 1000 ft. down it begins to get hotter. In other words, it would cost way more to dig it, reinforce the walls and create access than to heat it. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [January 10, 2024, 7:17pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/5 "2024-01-10T19:17:50Z")
Based on the news coverage over the last couple of weeks, there is no shortage of amateur tunnel-diggers who would apparently be happy to help out. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [January 10, 2024, 11:46pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/6 "2024-01-10T23:46:39Z")
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. ---
**Author:** ![Al128](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/al128/32/16541_2.png) [@Al128](https://boards.straightdope.com/u/Al128)\ **Post date:** [January 11, 2024, 2:58am UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/7 "2024-01-11T02:58:43Z")
the number I recall: for every 30m of depth +1°C ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [January 11, 2024, 5:51am UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/8 "2024-01-11T05:51:54Z")
> [@Hari\_Seldon](#): > > 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. 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. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [January 11, 2024, 2:21pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/9 "2024-01-11T14:21:14Z")
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. > **[US Groundwater Temperature - Bradley Corporation](https://www.bradleycorp.com/sizing-tankless-water-heaters/united-states-groundwater-temperatures)** > > Map of the United States showing groundwater temperatures to help size tankless electric water heaters ---
**Author:** ![scudsucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scudsucker/32/14101_2.png) [@scudsucker](https://boards.straightdope.com/u/scudsucker)\ **Post date:** [January 11, 2024, 3:01pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/10 "2024-01-11T15:01:09Z")
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. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [January 11, 2024, 3:10pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/11 "2024-01-11T15:10:00Z")
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. ---
**Author:** ![Railer13](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/railer13/32/9742_2.png) [@Railer13](https://boards.straightdope.com/u/Railer13)\ **Post date:** [January 11, 2024, 7:28pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/12 "2024-01-11T19:28:35Z")
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. ---
**Author:** ![StarvingButStrong](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/starvingbutstrong/32/335_2.png) [@StarvingButStrong](https://boards.straightdope.com/u/StarvingButStrong)\ **Post date:** [January 11, 2024, 7:35pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/13 "2024-01-11T19:35:01Z")
> [@TriPolar](#): > > Somewhere between 500 and 1000 ft. down it begins to get hotter. 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. 🙂 ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 12, 2024, 5:52pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/14 "2024-01-12T17:52:26Z")
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. ---
**Author:** ![3AxisCtrl](https://avatars.discourse-cdn.com/v4/letter/3/ecd19e/32.png) [@3AxisCtrl](https://boards.straightdope.com/u/3AxisCtrl)\ **Post date:** [January 13, 2024, 1:46pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/15 "2024-01-13T13:46:12Z")
> [@TriPolar](#): > > 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. It would be more accurate to say that at this depth the temperature remains close to the average annual air temperature. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [January 13, 2024, 1:51pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/16 "2024-01-13T13:51:29Z")
How deep to heat pumps need to go to work? I have seen 100 - 400 feet. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [January 13, 2024, 3:34pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/17 "2024-01-13T15:34:08Z")
A former client put in a horizontal loop in his back yard in MD and it’s only like six feet deep. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [January 13, 2024, 4:39pm UTC](https://boards.straightdope.com/t/how-deep-would-you-need-to-go-to-create-a-naturally-warm-basement/995907/18 "2024-01-13T16:39:11Z")
> [@Whack-a-Mole](#): > > How deep to heat pumps need to go to work? 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.