"Ignoramus10802" wrote in message
...
On 2009-10-29, Don Foreman wrote:
Savings begins the instant inside temperature is reduced, whether or
not it is stable at a lower setpoint. This is true regardless of how
well the house is insulated, what the thermal mass might be, who the
president is, which party controls congress or whether DOE likes it or
not. Rate of heat loss at any (and every) instant depends upon
temperature gradient from inside to outside.

Very well put.

But it has little to do with the question of whether you get any significant
energy savings from turning down the thermostat for relatively short periods
of time.

Again, if you shut it down for eight hours and the temperature drops, say,
12 - 15 degrees F (typical for my house), you will spend hours waiting for
the temperature to climb back up -- and (you do the calculus, not me g)
the benefit you get from it is LESS than the theoretical savings you would
have if you lived in a vacuum bottle and the temperature had dropped only 6
or 7 degrees for all of that time. Meanwhile, you're freezing your butt off,
part of the time at close to 12 degrees lower than your regular setting.

Are we together on this, Dr. Algebra?


Whether or not the savings on the energy bill is noticable is another
question depending on how much the setback was for how long.

I wonder how much the DOE spent on a study to address what would be an
easy test question in thermodynamics 101.

That study might have been a part of economic stimulus.

You guys had better figure in thermal mass and look up some values for
thermal mass versus R-values in a typical house. The calculation is not as
simple as you make it out to be. For a short time, as DOE says, the saving
is trivial.

--
Ed Huntress