I was reading what I think is Tony's blog, and the heating system he installed a few years ago is interesting.
The premise is a full basement with little insulation on the floor (I assume building regs minimum plus the 25mm on top of the slab), and shallow boreholes used to put excess heat into the ground under the house via waterpipe loops during the summer.
Rather than the pfaff about mega-insulated tanks of water or blocks of concrete, there is a simple reliance on heating up the ground under the slab.
Does anyone have any views on this, and @tonyshouse - does it work? ? Has it overheated, and if it did how would you manage that?
The idea of just using less insulation seems quite good under "reduce" as the first circuit of the green spiral. As an alternative use of heat that would be vented to atmosphere it seems a decent idea.
Articles:
http://tonyshouse.readinguk.org/heating-the-ground/
http://tonyshouse.readinguk.org/interseasonal-thermal-store/
Ferdinand