RE: [GBlist] Setback Thermostats, basic question

["Brad Andersen" <brad_s_andersen@hotmail.com>]

Hello,

     I have a LUX digital thermostat (HomeDepot ~$89) that gives you 4 
programmable timezones per day.  I have radiant heat that we set to 60 in 
the evening and 64 during the day.  This thermostat tells you how long it 
was on yesterday, how long it has been on today, and the total amount of 
time it has been on.  By tweaking your settings and monitoring the daily 
energy usage you could determine the maximum efficiency through the very 
scientific trial-and-error method with the help of some spreadsheets.  It is 
cheap and simple.  BTW, you can easily override the settings for those 
really cold days.

Good luck,
Brad


>From: "Ralph Bicknese" <ralph.bicknese@christnerinc.com>
>To: <JNH2@aol.com>, <greenbuilding@crest.org>
>Subject: RE: [GBlist] Setback Thermostats, basic question
>Date: Thu, 3 Jan 2002 11:20:14 -0600
>
>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




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