Forum » Energy Modeling Software » TRACE 700 » General

Using thermostats to reduce morning warm-up demand

9 posts / 0 new
Last post

I am currently running an energy model on an 80,000 sf medical office building. In my proposed case I have some large building demands and I am trying to find a way to model some demand limiting in the morning warm-up. I tried scheduling the electric reheat to reduce the demand in the morning, but that brings hundreds of unmet load hours, so I began trying to use 2 different thermostat settings, one turning on at 6 am and one at 5, and use them in my templates so that one floor warms up at 5 and the other at six, but my demand profile is still all on at 5. See attached demand viz.

Any suggestions?

Trace Viz
Oct 18, 2010
cmeoska's picture
cmeoska
Offline
Joined: 2010-10-05
Reputation: 1
Tags
You may want to chck if anything is going on with ventilation. Also, is it possible there is a base utility linked to the heating plant? It just seems like there is a "something else" factor.
Oct 19, 2010
Bob's picture
Bob
Offline
eQUEST UserLEED AP BD+CTRACE 700 User
Joined: 2010-06-30
Reputation: 475
I am using CLTD CLF for both heating and cooling. My setback is 5 degrees. Again, I don't know why one hour there is a huge spike while the next there is nearly zero demand. The spike is "Heating Equip (kW)" Fan Equip is green, so It shouldn't be the fan.
Oct 19, 2010
cmeoska's picture
cmeoska
Offline
Joined: 2010-10-05
Reputation: 1
I guess it wouldn't look so drastic if there wasn't such a spike. Are you using CLTD Methodology for cooling and TETD-TA1 for heating under the load parameters? And what is your unoccupied setback temp? Also, take a look at your fan/s, if it doing a calc to determine the optimum startup time and this overrides the fan schedule...it seems that you're spiking at the time the fan needs to run. Always start with the not so obvious of did I get the right units in the unit field, is the fan motor properly curved (unloaded). Is it VFD'd? Are you sure your fans are cylcing on occupancy?

Be Sustainable -- Never let today use up tomorrow!.

Oct 19, 2010
Bobba_Fett's picture
Bobba_Fett
Offline
Joined: 2010-10-01
Reputation: 229
I have optimum start scheduled as Available 100% I am using a thermostat schedule. A second weird thing is that there is an hour after the spike where the demand is nearly 0
Oct 19, 2010
cmeoska's picture
cmeoska
Offline
Joined: 2010-10-05
Reputation: 1
Ummm and yay for using the visualizer function to find this...

Be Sustainable -- Never let today use up tomorrow!.

Oct 18, 2010
Bobba_Fett's picture
Bobba_Fett
Offline
Joined: 2010-10-01
Reputation: 229
If that doesn't work, it seems a little fishy to me. Demand spikes like that aren't too common. I'm wondering if you could switch your driftpoints off or use a 24/7 tstat schedule and see if you have the same problem.
Oct 18, 2010
Bob's picture
Bob
Offline
eQUEST UserLEED AP BD+CTRACE 700 User
Joined: 2010-06-30
Reputation: 475
[quote=Bobba_Fett]Have you looked at the Advanced Options under the Systems/Options Tab? I usually pick the Optimum Start 5-7am, but find that it causes the same issues unless you copy/alter as you need for your people schedule. Start the equipment at least an hour before occupancy gets >5%. Set your thermostat schedules back to none.[/quote] The only thing I'd change about these instructions is I'd use the "Available (100%)" schedule for Optimum Start. In recent version of TRACE the "Available (100%)" used in Optimum Start runs an algorithm that decideds at what time prior to occupancy the system(s) need to come on to limit unmet hours.
Oct 18, 2010
tracewindu's picture
tracewindu
Offline
LEED EA Credit 1 TrainingTRACE 700 User
Joined: 2010-10-10
Reputation: 8
Have you looked at the Advanced Options under the Systems/Options Tab? I usually pick the Optimum Start 5-7am, but find that it causes the same issues unless you copy/alter as you need for your people schedule. Start the equipment at least an hour before occupancy gets >5%. Set your thermostat schedules back to none.

Be Sustainable -- Never let today use up tomorrow!.

Oct 18, 2010
Bobba_Fett's picture
Bobba_Fett
Offline
Joined: 2010-10-01
Reputation: 229