5 ms·

Exactly. The ground is usually 58F. I remember reading about this in a thermal home book. (If you effectively bury 3/4 of your house, you only ever have to warm

Exactly. The ground is usually 58F. I remember reading about this in a thermal home book. (If you effectively bury 3/4 of your house, you only ever have to warm it to 70F from 58F.) It's actually somewhat funny. Did they think there were ice cubes under the grass when the designed this?

zokier 12y ago
> Did they think there were ice cubes under the grass when the designed this? Permafrost does exist, albeit not at Denmarks latitudes.
lutorm 12y ago
AFAIK, the ground temperature will be the average air temperature over the year. It's certainly not 58F everywhere, because in Siberia there's permafrost, and in Denmark might likely be less than 58F, too.
- zokier 12y ago
  Based on quick search, the average air temperature in Denmark is 8-9°C(46-48F)[1]. I suspect that you don't find that cold ground temperatures though. I found some local statistics about ground temperature[2], which shows that even around here the invention would barely work in the warmest months. And I'm living nearly thousand miles northwards from Denmark, from the same source the average air temperature here is -2°C. I'm just giving this as more nordic perspective, seeing that most HNers probably are from US/warmer climate. [1] http://www.dmi.dk/en/klima/klimaet-frem-til-i-dag/danmark/temperatur/ http://www.dmi.dk/en/klima/klimaet-frem-til-i-dag/danmark/te... [2] http://i.imgur.com/LrUEPP7.png http://i.imgur.com/LrUEPP7.png ground temperature at various depths
  - lutorm 12y ago
    And I'm living nearly thousand miles northwards from Denmark That's far north... Tromsø? Kirkenes?
    - zokier 12y ago
      > Kirkenes? Close but wrong side of the border :) I'm currently (stuck) in Ivalo[1], family home is in Utsjoki [1] https://www.google.com/maps/place/99800+Ivalo/@68.6499997,27.55,7z https://www.google.com/maps/place/99800+Ivalo/@68.6499997,27...
msandford 12y ago
The ground is not usually 58F. It depends entirely upon where you live AND how deep you go. Where I live, in Houston, TX the readily-accessible ground temperature is in the high 60s or low 70s.
- fivedogit 12y ago
  For the purposes of a just-below-the-surface cooler, yes I believe you are right. But my understanding from the book is that if you go slightly deeper, you will get to a somewhat universal soil temperature no matter where you actually are, with extreme counterexamples, I'm sure. The book, on thermal housing, may have been assuming habitable areas, not Antarctica or Siberia.
  - msandford 12y ago
    Check here: http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/31492/afv/topic/Default.aspx http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/... The 3rd post talks about the variation in temperatures. Seems that once you get to around 30 feet down the temperature becomes constant year round. For Houston the chart says 71 degrees. Because it's that single number instead of a range I assume that's the temp you get at 30 feet deep.

zokier 12y ago

> Did they think there were ice cubes under the grass when the designed this? Permafrost does exist, albeit not at Denmarks latitudes.

lutorm 12y ago

AFAIK, the ground temperature will be the average air temperature over the year. It's certainly not 58F everywhere, because in Siberia there's permafrost, and in Denmark might likely be less than 58F, too.

zokier 12y ago
Based on quick search, the average air temperature in Denmark is 8-9°C(46-48F)[1]. I suspect that you don't find that cold ground temperatures though. I found some local statistics about ground temperature[2], which shows that even around here the invention would barely work in the warmest months. And I'm living nearly thousand miles northwards from Denmark, from the same source the average air temperature here is -2°C. I'm just giving this as more nordic perspective, seeing that most HNers probably are from US/warmer climate. [1] http://www.dmi.dk/en/klima/klimaet-frem-til-i-dag/danmark/temperatur/ http://www.dmi.dk/en/klima/klimaet-frem-til-i-dag/danmark/te... [2] http://i.imgur.com/LrUEPP7.png http://i.imgur.com/LrUEPP7.png ground temperature at various depths
- lutorm 12y ago
  And I'm living nearly thousand miles northwards from Denmark That's far north... Tromsø? Kirkenes?
  - zokier 12y ago
    > Kirkenes? Close but wrong side of the border :) I'm currently (stuck) in Ivalo[1], family home is in Utsjoki [1] https://www.google.com/maps/place/99800+Ivalo/@68.6499997,27.55,7z https://www.google.com/maps/place/99800+Ivalo/@68.6499997,27...

msandford 12y ago

The ground is not usually 58F. It depends entirely upon where you live AND how deep you go. Where I live, in Houston, TX the readily-accessible ground temperature is in the high 60s or low 70s.

fivedogit 12y ago
For the purposes of a just-below-the-surface cooler, yes I believe you are right. But my understanding from the book is that if you go slightly deeper, you will get to a somewhat universal soil temperature no matter where you actually are, with extreme counterexamples, I'm sure. The book, on thermal housing, may have been assuming habitable areas, not Antarctica or Siberia.
- msandford 12y ago
  Check here: http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/31492/afv/topic/Default.aspx http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/... The 3rd post talks about the variation in temperatures. Seems that once you get to around 30 feet down the temperature becomes constant year round. For Houston the chart says 71 degrees. Because it's that single number instead of a range I assume that's the temp you get at 30 feet deep.