Energy Matters Forums

[Carl]

Hi! I'm new to this caper, so I hope I'm right to start to a new topic.

I am planning a new house in country SA, and am keen on trying cool earth pipes, buried in the ground and coming under the slab, to reduce the amount of A/C needed on hot days. I know that the pipes need to be buried 1.4-1.5 m deep, and the longer they are the better. But our architect, who is a leading eco. architect in SA, isn't too keen on these pipes, and I'd like to find out if someone has done any more research or experimentation on them. For example, I was thinking of having 4x90mm PVC storm water pipes, going the length of the slab (ca. 18 m) and then 20-30 m outside. Would these do any good? I know that PVC is not ideal, but it has certain advantages. Inside the room where the pipes come up, I'd have an exhaust (probably solar driven) to draw the hot air out of the room and thereby the cool air up through the pipes.

My aim is just to reduce the amount of A/C that would be needed, not to avoid A/C altogether.

Any suggestions on whether I would be wasting my time and money installing the pipes before the slab went down would be appreciated.

[Tracker]

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As a supplementary system, it must surely work. The only thing that I would suggest is that you might consider some filtering, in case a pipe leaks, water gets in and you develop mould ..

Were I going to that trouble , and a trench was open, you might think to bury Copper-Pipes, with the view of cooling water, or heating water by a parallel system. (ie Heat Pump)

Even to buy a roll of 3/8 Cu pipe and roll it out to be used in a Home-Made Heat-Pump system. That would be real cheap (after the trenching)

Gordon - ( Gordon-Loomberah ) is right up on this stuff, and there have been various threads discussing it (including burying POLY-PIPE.)

Good Luck
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[Gordon-Loomberah]

As Tracker mentioned, there has been a fair bit of discussion of buried pipes for cooling air, have a read through them and let us know if you have any other Qs.

You do need to ensure the pipes stay dry inside, so a drainage system needs to be worked out to remove any accumulated water. You dont want to be pumping the house full of legionaires! Water will condense in the pipes if the deep soil temperature is below the dew point of the air you draw through the pipes.

[Carl]

Thanks you 2 for that. But where can I find more discussion on this. I've looked at all the topics and none of them seem relevant, and I've tried the Search key, but that only refers me to 2 posts, mine and yours! So I'm lost in that regard. Carl.

[Gordon-Loomberah]

A quick search brought these up- look through the whole thread rather than just the posting the links lead to.

http://forums.energymatters.com.au/post788.html?hilit=pvc%20pipe#p788

http://forums.energymatters.com.au/post1819.html?hilit=pvc%20pipe#p1819

http://forums.energymatters.com.au/post3440.html?hilit=pvc%20pipe#p3440

[jasonedu]

i tried to look into this when planning our current house. it makes sense but there is very little published information showing it was worth while and in the end I decided not worth the effort. I seem to recall it being more effective in damp well shaded soil but there were so many variables involved there was no way to be certain it would work. The final straw was an consultant from Goulburn who said he had never seen a system that worked well.

if you are building from scratch maybe you should instead be thinking about ventillation and air flows through your house and ensuring walls and windows are shaded from the summer sun. A concrete slab that is not thermally isolated (we used polished concrete) from the ground and that is kept shaded will probably have more impact on temperatures than a cool earth tube.

[jaybee379]

We used PVC, and buried it about half a metre down. Not deep enough !

Also, we would appreciate the cool night air being brought through the store room (we use the pipe to cool a food store room). So - an active device (fan) running at night (in summer) would really help - we currently have a dark painted metal pipe out of the roof (so it acts as a solar chimney during the day) - but that has not worked out as well as we would have liked, and simply sucking the cool night air in (either through a buried pipe or direct through a low vent in the door) would be better.

Our store room has straw bale walls, is on the west side of the house, and certainly feels cool - but it does get over 20 degrees in summer, which is warmer than we want it to be (and warmer than the night air temperature).

John Barlow
Bega

[Laurens]

The other thing I have seen is an internal stone or very thick brick wall. The density of the wall keeps the temperature inside the house very stable.
In the 70's, in Melbourne, houses were being built with central stone piles (enclosed in a room) these rooms were used as temperature storage rooms that were ventilated by electrically controlled vents and fans....

[Gordon-Loomberah]

The other thing I have seen is an internal stone or very thick brick wall. The density of the wall keeps the temperature inside the house very stable.
...

A large tank of water would be much more effective than brick or stone- it's able to store ~twice as much heat as granite per volume, and 5 times as much per weight. It costs a lot less than a stone or brick wall too.

[Laurens]

what will the tank be made out of?