It’s good to be able to save heat like that Stella.
Problem is when I take mum out in her wheelchair I have to have the front door wide open while I steer her down my home made (very proud of it) ramp. Then I have to leave her at the bottom and rush up to shut and lock front door! You can imagine how the cold rushes in during this, especially as we are in an exposed position.
Have told her she will have to hibernate until it gets warmer 
Good grief… yes, you have to leave it open… oh dear…
you’ll have to rig up some sort of Heath Robinson gizmo that automatically shuts the door behind you… 
All instructions and devices gratefully received 
Why not fit one of those foot activated door stops onto the door coupled with a closing spring. Open the door push down on the stop till it’s rubber foot hits the floor as you leave flick it off with your foot Spring then shuts the door enough to minimize the heat loss. Toolstation.fr is a great mail order company for all such things
Hello Andy, thanks for the idea, my door is an old one that I have to wiggle the handle and slam before it settles into place. If I do get a new door I will certainly look at having one though .