The second law of thermodynamics comes in handy. And Stefan Boltzmann already thought about this, too :)
That given, #2 results in "the lowest temperature to minimize the rate of heat loss is equal the outside temperature. Equilibrium."
It makes sense to turn off the heat when going out of house. In the that time, the house loose energy and it makes sense not to spend more energy to heat & keep a certain temperature. But the house will lose in one way or another anyway, so pulling the temps down makes totally sense.
That given, #2 results in "the lowest temperature to minimize the rate of heat loss is equal the outside temperature. Equilibrium."
It makes sense to turn off the heat when going out of house. In the that time, the house loose energy and it makes sense not to spend more energy to heat & keep a certain temperature. But the house will lose in one way or another anyway, so pulling the temps down makes totally sense.