13 Sept : I am grateful that my erstwhile structural engineer colleague Peter Fawcett writes to me from Hobart, Tasmania,
"Charging-the-earth is an interesting idea: I guess the efficacy would be dependent on the local geology, in particular any groundwater flows."
"I have a groundloop heatpump system here, thence into slab coils. The context was right: plenty of space on an equator-facing slope (hence a bit of solar top-up to the ground even in winter) but couldn't go all that deep because of rock. But it seems to work. Unfortunately the Australian market for geothermal is quite small and the only appliance manufacturer with an agent here is the American WaterFurnace. The agent is in Sydney and the technical support in Adelaide - each about 2000km from Hobart!"
"There's an interesting issue of control because of the timelag of the floor slabs, combined with the wide changeability of our weather systems. What it needs is direct input from the government weather-forecasting service to a timer-controller. Meanwhile. it keeps me amused to try and anticipate demand."
"Many other interesting points on your blog. The issues here in Oz are similar but different, if you get me."