Jim:
<Actually what I am hoping to come
across someday is a piece of software that will take the input from external
temperature sensors and coordinate the building's systems to avoid over
cooling/heating while still maintaining the maximum amount of set-back - of
course that is not prohibitively expensive.>
There are such systems in use for
commercial buildings. Honeywell,
Johnson Controls, Trane, etc sell the controls. But, I am not confident how
well they work. I think they often
do not predict correctly. They cannot
tell when there will be rapid changes in temperature, cannot predict the effect
of cloud cover, etc. I still think
the best way is to judge by how you feel and react accordingly. Your method to determine appropriate
comfort levels for various setbacks seems very sensible to me. The simpler the system is, the better. Especially for houses, simple programmable
setback thermostats work very well once adjusted correctly.
Cheers,
Ralph Bicknese
-----Original
Message-----
From: JNH2@aol.com
[mailto:JNH2@aol.com]
Sent: Wednesday, January 02, 2002
9:55 PM
To: greenbuilding@crest.org
Subject: Re: [GBlist] Setback
Thermostats, basic question
Sounds
like a good question for all these experts to tangle with.
We have set-back thermostats (in a residence) that allow for 4 different
time/temperature settings during the week (day 1 through day 5) and another set
of 4 time/temperature settings for the weekend (Day 5 & 6)
We have found that in a heating situation a setback of between 5 and 8 degrees
works pretty well, and is able to compensate (at least to our perception) in
the morning and late afternoon when it is programmed to come back up to a
comfort level.
In a cooling situation, 5 degrees seems to be the maximum for a reasonable
transition in the morning and afternoon, allowing the building to get warmer
than that takes much longer to cool down.
With an entire weekend and a full 10 hours each night, you could rather easily
set the t-stat to start ramping up somtime around 5:00am - so that for weekends
you could tolerate a much cooler/warmer temperature with several hours to get
up to comfortable temperature Monday morning.
The way to determine just where you want to set the thermosats back to is to
start with a reasonable guess (8 degrees, 10 degrees, ?) and using a separate
thermometer, check to see on similar weather days how long it takes the
occupied spaces to get to a comfortable level. A good guess would be to
set-back 10 degrees and expect the system to take roughly 2 1/2 to 3 hours to
compensate.
There are much more complicated formulae, and figuring that could work up the
ideal times and set-back numbers, but that would mean a constant monitoring and
adjusting of the set-back numbers and times.
Actually what I am hoping to come across someday is a piece of software that
will take the input from external temperature sensors and coordinate the
building's systems to avoid over cooling/heating while still maintaining the
maximum amount of set-back - of course that is not prohibitively expensive.
my thoughts, for what they are worth.
good luck,
Jim Holdcraft
Saint Louis
