I don't have a direct answer to this question ... but wonder if it's worth it.

Wouldn't heat in the Pile try to work upwards mainly?
If heat is lost to the ground immediately below the pile wouldn't this eventually serve to reduce the temperature gradient between the two ... so there's a "buffer" of sorts at the end of the pile?

Think there are others on here who could put it more clearly and more technically.

Posted By: ShevekIs there any kind of insulation out there that can go under foundations?

Not as far as I know, except for the foam raft under concrete slab type. With piles there are some things you can do to reduce heat loss:

- Insulate the sides of the piles, so the heat has to travel all the way to the bottom to 'escape'.
- Increase the depth of the piles so the heat has to travel further.
- Decrease the thermal conductance of the piles by changing materials - this can be a little more complicated than it might first seem. You might think that using timber is better than steel, for example, but you need a lot less cross-sectional area of steel so it's not straightforward. Sums need to be done!
- Insert a thermal break - it might be possible to add one of the proprietary load-bearing thermal break pads at the top of the pile.

All of these things complicate the build and cost money, so it's best to do a full analysis to see what is worthwhile.

Posted By: ShevekWhat about additives to the concrete?

You can play games by changing the aggregate to more insulating materials - I think leca and foamed glass are sometimes used, but I'm no expert. But clearly you need a concrete expert to design a mix that is fit for purpose as well as helping the insulation.

Don't know about the Claymaster but I'd be interested if you do find anything out. We've got clay under our plot.