Here's the scenario: We have a programable A/C. Nobody is home Monday-Friday between 7am and 5pm. Assume we'd have the A/C set to 75 degrees. Here's the question: Would it be more cost efficient to have it set to keep a constant temp of 75 degrees all the time, OR would it be better to have it off during the day and come on about an hour before we got home and have it cool the house down to 75? My thought is that it may run more frequently if we have it set to maintain 75 degrees, but it wouldn't run as long as it wouldn't need to cool down as much. So, which way is more efficient?