Green Building Forum - There aint no such thing Wed, 26 Aug 2026 07:14:48 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120629#Comment_120629 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120629#Comment_120629 Tue, 25 Oct 2011 10:07:30 +0100 tony
THERE AINT NO SUCH THING!!

This term is becoming more common and is incorrect in, we have talked about them before and agreed that it was an incorrect description.

A heat pump uses solar energy, heat from the sun stored in the air, water or in the ground. They should not be described as geothermal.]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120631#Comment_120631 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120631#Comment_120631 Tue, 25 Oct 2011 10:22:50 +0100 fostertom There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120633#Comment_120633 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120633#Comment_120633 Tue, 25 Oct 2011 10:39:27 +0100 JSHarris
I once went down a Cornish tin mine (when they were still working) and down at around 400 m or so it was like a sauna, pretty uncomfortable even wearing just an overall and little else. I'd guess that the temperature down there was 30 deg C plus.

Even a few metres down in that neck of the woods you can get significant "geothermal" heat, although some of it is really nuclear (the granite has small amounts of nuclides and their decay warms the rock).]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120636#Comment_120636 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120636#Comment_120636 Tue, 25 Oct 2011 10:51:51 +0100 SteamyTea Radioactive decay is is estimated at 5 x 10^20 J.a^-1
So not sure where you have that thermometer.

A lot depends on local geology. Around here here there is a lot of radioactive decay near the surface, but still tiny compared to the solar absorbed by the rocks. Though a lot of heat pump energy comes via water that has run off the surface and soaked into the ground. This increases the capture area immensely. Rainwater is very definitely solar energy. Though yesterday there was lots of rain and little sun!]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120637#Comment_120637 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120637#Comment_120637 Tue, 25 Oct 2011 10:58:31 +0100 Peter_in_Hungary
I would agree however that geothermal is both over and mis used as a term and most (or all!) GSHP in the UK are going to be stored solar energy]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120641#Comment_120641 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120641#Comment_120641 Tue, 25 Oct 2011 11:26:23 +0100 fostertom Posted By: SteamyTeaEarth average is 60 mW/m^2As little as that? somewhere I have a map showing enormous differences even leaving aside hotspots like Iceland. Old rock masses like most of Africa v low; ocean beds v much higher; mixed geology like western Europe in between.

Posted By: SteamyTeaa lot of heat pump energy comes via water that has run off the surface and soaked into the ground
That only applies during the summer solar-replenishment phase; will actually be a ground-cooling mechanism in winter. In any case, does not widen the catchment area of solar collection.

What may (or may not - it's a lottery) contribute greatly as prime source of heat collected by GSHP, is groundwater flow, either horizontal by mass flow, or vertical by water table rise and fall.]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120651#Comment_120651 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120651#Comment_120651 Tue, 25 Oct 2011 12:31:46 +0100 Paul in Montreal Posted By: tonyA heat pump uses solar energy, heat from the sun stored in the air, water or in the ground. They should not be described as geothermal.

The more correct term is ground-exchange heat pump, or ground source heat pump - the former term for reversible systems (like mine) that do heating and cooling, the latter for heating-only systems (like most, if not all, of those sold in the UK).

Paul in Montreal.]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120656#Comment_120656 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120656#Comment_120656 Tue, 25 Oct 2011 13:26:05 +0100 SteamyTea Posted By: fostertomThat only applies during the summer solar-replenishment phase; will actually be a ground-cooling mechanism in winter. In any case, does not widen the catchment area of solar collection.
There is solar gain in other times/ways/places as well.
Think where the rain predominately comes from, (in the UK, Canada's will be a USA import :wink:), after a few phase changes it falls as either rain, hail or snow. All ways it is energy transfer from the tropics to the higher latitudes, we would be, at 50-60N a lot colder without it. Convert from the Celsius to the Kelvin scale to get a true measure of it.]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120662#Comment_120662 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120662#Comment_120662 Tue, 25 Oct 2011 14:00:59 +0100 fostertom Posted By: SteamyTeaThere is solar gain in other times/ways/places as well.But not nett positive at night vs day, winter vs summer, temperate zones vs tropics. For UK, definitely nett negative, winter time. Whatever is gained winter daytime is more than lost by radiation to night sky.

Posted By: SteamyTeaAll ways it is energy transfer from the tropics to the higher latitudes
True, but only on a summer + winter nett basis. In winter alone, precipitation is cooling the ground - mostly falling @ well below the 10C av 2-3m deep u/ground temp.]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120674#Comment_120674 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120674#Comment_120674 Tue, 25 Oct 2011 15:13:31 +0100 SteamyTea Posted By: fostertomprecipitation is cooling the ground
But not all of it. If you think of the SHC of water, and then how much falls as rain onto given a m^2 of ground, you can work out the energy transfer. This has to be against the backdrop of how a heat pump extracts energy from the ground. It uses a fluid that is cooled to around 0C (or 273K in real money), that fluid is then warmed slightly before it cools in the HP. Now as water hold more energy per unit mass than soil, as long as it is above 0C when it soaks in, more energy can be extracted at a higher rate from wet ground than dry ground even if the overall temperature is lower. Sounds odd, but it works.]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120678#Comment_120678 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120678#Comment_120678 Tue, 25 Oct 2011 15:37:09 +0100 bot de paille If the energy is more easily available to the GSHP then it is also more available to be "lost" to the surrounding environment and will therefore dissipate quicker.

Im talking over a period of days or weeks, you are shortening the grounds capacity as a heat battery.

If the moisture was sealed inside the ground immediately around the GSHP circuit, the effects would be different, more beneficial...?

presumably badgers dig their burrows below the frost line?]]> There aint no such thing https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120680#Comment_120680 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8011&Focus=120680#Comment_120680 Tue, 25 Oct 2011 16:17:56 +0100 SteamyTea Posted By: bot de paille
presumably badgers dig their burrows below the frost line?

Heavier than air gas needed then :wink:]]>