So here are some photos.
Our house is on a steep block and the garage is separate from the house itself. Because of the slope, there is plenty of space below the actual garage and there was a room which housed the old air-conditioning compressors. The outer walls are double brick and the inner walls singe brick i repurposed that room for the cellar and you can see the results.
The paint still needs some touching up. I’ve got custom shelves on the bottom half for wine still in boxes and racking above. I wanted the diamond shaped shelving instead of racking but it was too expensive so just got the wire ones, which are fine. I got a different racking system for the spot behind the door where the bottles lie sideways. Some sparkling bottles don’t fit the normal racks so will probably use those more.
You can see I still have quite a bit of space to fill
The floor is concrete slab and the builder had some leftover engineered floorboards which they laid on top.
I also too a photo of the edge of the door so you can see the depth of the insulation. That covers the walls and ceiling with plasterboard over the top.
For the outside wall which gets the sun - this is double brick with the insulation then inside that.
The one weak spot is the seal around the door. It’s more or less airtight but there is a bit of a gap in the insulation. The hood over the door stops most of the direct sun onto the door and so I think is adequate.