The garage concrete shell is now complete.  Set into the ground on two sides, it will have a hedge to the south and decking over and I wonder how the internal temperature will vary.  It’s thermally massive at 300mm concrete all round but insulation was dropped at the last minute due to cost.  I expect the thermal mass will seriously dampen the daily fluctuations but the temperature will vary considerably over the year and won’t be much good for storing wine!  We did look at a simple ground loop to chill a small compartment in the garage as a wine store but it seemed overly complicated in the end.