[GBlist] re: setback thermostats, basic question

[Chris Koehn <chris@koehn.com>]

Title: re: setback thermostats, basic question

Corwyn wrote:

"Also, don't let anyone tell you that the energy to bring it back up to
temperature negates the savings of lowering the temperature.  The heat
loss of the building is proportional to the difference in temperature
between inside and outside".

In my experience, again, this is system dependent. In our geo thermally heated house, it would certainly take more energy to bring us back up to set point, because geo thermal systems aren't designed to deal well with dramatic changes in load. So our back up resistance electric heat would kick in, which would cost us way more than just leaving the system at set point (unless we were going to be gone for a very long time). And again, in the case of our last home, which was super insulated with a lot of thermal mass, the savings is (there, but) negligible, unless the set back is for an extended period of time (which we determined in our case to be 48 hours). That said, a "normal" framed home with FHA heat can benefit to a much greater degree from a setback thermostat than we can.

One can't make blanket statements about the usefulness of set back programmable thermostats without knowing more about the system they are working within. 

Chris