Expert: Ted Barnhill (Principal, Design45 LLC) - 1/21/2009

Question
Hi Mr. Barnhill,
Quick question-- We have a new home, two floors, two thermostats, forced air heating.

In your experience, which would you say saves more money and oil---  
a) Leaving the thermostats on 24/7 to maintain a steady temp  or  
b) Turning the heat off when leaving for a couple hours and leaving the lower level off at night?    

My husband says that the latter may not be saving because the system has to work overtime to get the house back up to par again once we turn the heat back on.  

What would be your advice?

Answer
Chris,

I hate to get in between the two of you, but I do feel strongly about saving energy, so here goes: you are correct.  It saves money to heat your home only when you need it.

The amount of energy that you use to heat your home is approximately equal to the amount of energy that escapes your home through the walls and roof.  As your home is new and therefore probably relatively free of air leaks, the amount of energy lost is directly proportional to the difference in temperature between outside and inside.  So, the warmer you keep your home, the more energy escapes.  If you use timers to set back your thermostats overnight and when you are out of the house, your furnace will run less during those periods.  True, your furnace will likely run at full power for a while when bringing the house back "up to par," but this cost is far outweighed by the savings of running less during low-temp times.

I hope this help settle your dispute.  Stay warm efficiently this winter!  -Ted