Wow, I have learnt something cool, from Gladwell’s blog already, (not hard when you have a backlog to read) using the constant ground temperature for heating/cooling.
People just love heat pumps here in New Zealand, but the downfall of heat pumps is performance when it is really cold weather. I knew about the earth constant temperature, having visited an ex-military underground base, and been told it was always 18°C. Putting the two ideas together for heating is just brilliant.
Now if I only had the backyard to lay the piping in.