Quote Originally Posted by Allan Dozier View Post
…… My position is that any amount of setback will save energy as long as we are talking about single speed heat pumps with heat strips turned off or fossil fuel furnaces. There is no penalty for "catching up" in the morning for those units, they don't work any harder just longer. It takes more energy to keep the downstairs warmer through the night than it takes to warm it back up in the morning. . . .
After retiring from the classroom I headed our school district’s newly formed energy conservation program. We studied our various systems and had engineers consult and study our systems. There are several buildings with all electric, geothermal, and mixed air handling systems.

Allan’s comments above pretty much summed up the conclusions. You always saved energy with a setback; pretty much just a matter of physics. However, that did not correlate to a savings in expenses. Because of our utility’s billing method, electricity after about 7:00 am was more expensive. Our elementary students arrived at 8:00 and it generally took about an hour to get our buildings from our 55° setback to our 68° occupied set point. But, that was the most expensive time for energy. It was cheaper to start heating the building about 5:30 to about 71°, maintain that from 7:00 to 8:00, then drop it to 68° when the kids were opening and closing outside doors when they arrived.

As suggested in a previous post, let your building get colder and see how long it takes to heat with various outside conditions. Then you can make calculations on any energy and money savings.