Glass doors are common in New Zealand homes.
Glass doors are cold doors.
South-facing glass doors are especially cold.
Here is a cheap and easy way to retrofit a four panel rimu glass door into a warm and cosy door. First, find yourself a comfortable working area and lay out the door.
Next, cut insulation to cover each glass panel on both sides.
Finally, cover with thin ply, hardboard or other suitable material. I used the waterproof wallboards that we removed from the old laundry when we extended our kitchen. They were just sitting in the shed.
Hang the insulated door and paint the lot.
(Note the second door handle is for our three year-old daughter.)
Not 100% flash, but a very high performance door at a low price.