you ramble, you know that it is not applicable to the individual, on the other hand the roller tunnel yes.
And no I'm not rambling, especially since at the end of Brittany, it freezes very little, unlike central Canada, at an altitude of 1000m, with -30 ° C instead of the rare freezes at 0 ° C at the end of Brittany !!!
The pebble tunnel is nonsense for the winter, with low reserves, and various drawbacks, like expensive, and full of heat pumps, with scams, like I was the victim, by trusting a trustworthy architect !!!
But, I see that almost all of you are like sheep to follow others, even if it leads to absurdities stuffed with heat pumps, by refusing what is coherent, and new, free in perpetuity, without pollution, indestructible, etc ..., adding creativity, instead of copying others like sheep.
PS: my heat pump was particularly usable !!!