Protractor Doormat

Besides using it to measure the angle of an opened door, it can also be used to control the temperature inside in the same way of using a thermostat. For instance, if the temperature inside is cold and the temperature outside is hot, opening the door at a 50° angle will add 50° to the temperature on the inside. On the other hand, if the temperature inside is hot and outside is cold, opening the door at a 50° angle will minus the temperature inside by 50°. However, it will not be as accurate as a thermostat.