Re: [EnergyPlus_Support] Starting simulation temperature

[Linda Lawrie <linda@xxxxxxxxxx>]

It is not a user-settable option.  The warmup takes care of any 
drifts caused by using that as starting temperature.

Search on "warmup" in the documentation for numerous mentions.  In 
the Building object:
Field: Loads convergence
This value represents the number at which the loads values must agree before
"convergence" is reached. (Units for this field is Watts.)
Field: Temperature Convergence
This value represents the number at which the zone temperatures must 
agree (from previous
iteration) before "convergence" is reached. (Units for this field is delta C).
Convergence of the simultaneous heat balance/HVAC solution is reached 
when either the
loads or temperature criterion is satisfied.
All tolerances have units so the temperature tolerance is in degrees 
C (or degrees K) and the
loads tolerance is in Watts. Both tolerances work the same way, just 
one looks at
temperatures and one looks at heating and cooling loads. After the 
second warm-up day, the
program compares the maximum temperature experienced in a space with 
the maximum
temperature from the previous day. If those two temperatures are 
within the tolerance, then it
has passed the first warm-up check.
It does a similar comparison with lowest temperatures experience 
within all the zones. If the
current simulation day and the previous day values are within the 
tolerance, then it has
passed the second warm-up check. Similar things are done with the 
loads tolerance and the
maximum heating and cooling loads that are experienced within the 
spaces. Those are
compared individually to the values for the previous day. If they are 
both in tolerance, then
the simulation has passed the third and fourth warm-up check. The 
simulation stays in the
warm-up period until ALL FOUR checks have been passed.
Please note--other "convergence tolerance" inputs are required for 
certain HVAC equipment
(unit ventilator, unit heater, window AC, etc.). The purpose and 
units of these parameters are
different from "load convergence tolerance" and "temperature 
convergence tolerance" in the
BUILDING object.


Linda

EnergyPlus WebSite: http://www.energyplus.gov
Owner: EnergyPlus_Support list
Member: EnergyPlus Development Team



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