This is a super simple instructable that will help you conserve heat in the warm rooms you like to hang about in.
If you have a door that other members in your household love to leave open, letting out all the warmth you so desperately want to keep in the room, then you might find use of this little hack.
All you need is a thick rubber band and two drawing pins. You will stick the pins into the wooden door and door-frame so make sure you have permission to do this.
Stick one of the pins on the door frame a bit away from the door and in a way the rubber band does pull the pin out. You could do this on the top of the door but I chose to at the bottom.
The second pin goes on the door such that the rubber band is stretched when the door is open. Stick it in, test if it can close you door, if not then move it further down, use a stronger rubber band, or more of them. You could also try oiling the door hinge to help thing move smoothly and reduce some of the friction.
There's not an exact science to this so try it out and good luck.