Cooling coil energy is very high even during a summer setback period

edit

Thank you rraustad ! I changed the setpoint manager as you mentioned, but now I am getting few severe errors during the simulation. Can you please recommend/suggest any checks that I should do to avoid those errors of convergence ?

Error file: https://estesmcclure01-my.sharepoint....

Updated IDF file: https://estesmcclure01-my.sharepoint....

Appreciate your time and help !

Regards, Biraj

The low temperatures causing the severe warnings are usually caused in zones where the temperature is not maintained. I did not have Dallas weather so I used Phoenix and it ran through the year. I would check some zone temperatures to see if the thermostat set points are met. I see you are providing the coil sizes and those values may not be able to meet the load. Check all warnings in the err file and fix as many as you can. Also, you should upgrade to the latest version since bugs are fixed and if this is a bug could have already been corrected.

If you don't mind, could you please see if the model will run on dallas file ? I am still running issues on a different weather file.

[Here is the link:] (https://energyplus.net/weather-locati...)

Thank you very much !

Well, I did run using the Dallas weather and it stops with the same low temp warnings. I also notice you mix autosizing with hard sized coil inputs.

Autosize, !- Low Speed Gross Rated Total Cooling Capacity {W} 0.51914218752, !- Low Speed Rated Air Flow Rate {m3/s}

This results in a very low air flow per capacity (cfm/ton) and can lead to very cold coil outlet temps. Not sure if that is was is causing this error or not. Continued in next comment...

0.51914 / 4522.61121 = 1.14788E-4, oh, this flow ratio is too high for DX coils. I suggest autosizing all autosizable input.

Component Sizing Information, Coil:Cooling:DX:TwoSpeed, 2 SPD DX CLG COIL 121, User-Specified Low Speed Rated Air Flow Rate [m3/s], 0.51914
Component Sizing Information, Coil:Cooling:DX:TwoSpeed, 2 SPD DX CLG COIL 121, Design Size Low Speed Gross Rated Total Cooling Capacity [W], 4522.61121

I ran this file in the soon to be released V9.6 and it also failed using Dallas weather. There are 3 Mechanical Ventilation controllers that are not set up properly. You should see these same errors in your version.

CONTROLLER MECHANICAL VENTILATION 3
CONTROLLER MECHANICAL VENTILATION 11
CONTROLLER MECHANICAL VENTILATION 63

Hi rraustad,

Thank you very much for your suggestions.

First iteration: I changed the low speed inputs for DX coils to Autosized (kept high speed hardsized). The simulation still did not ran.

Second iteration: I changed all the input to autosized, the simulation ran with very high EUI.

Third iteration: I downloaded latest OS version 3.2 (I was initially using 2.9.1) and ran the file from first iteration, still the same error.

Can you please clarify what do you mean when you say the controllers are not set properly ?

Also, here is the latest error summary from the update version run:

Final Error Summary ===== *** The following error categories occurred. Consider correcting or noting. *** Incomplete View factors *** ..Incomplete view factors can result from incorrect floor specifications (such as tilting 0 *** ..instead of 180) or not enough surfaces in a zone to make an enclosure. The error message *** ..also shows an enforced repciprocity value. You can decide if you need to make geometry *** ..changes based on that value. *** Loads Initialization did not Converge

1) very high thermal mass such as very thick concrete (solution: increase max number of warmup days in the BUILDING object); 2) moderate mass and inadequate space conditioning such that the building keeps getting warmer and warmer on successive days (solution: add HVAC, check building thermal properties, check if infiltration is included, make sure HVAC properly controlled); 3) a soil layer modeled below the concrete slab - (solution remove this layer and read about ground temperatures in the Auxiliary Programs document).

Nominally Unused Constructions The nominally unused constructions warning is provided to alert you to potential conditions that can cause extra time during simulation. Each construction is calculated by the algorithm indicated in the HeatBalanceAlgorithm object. You may remove the constructions indicated (when you use the DisplayExtraWarnings option).

EnergyPlus Warmup Error Summary. During Warmup: 0 Warning; 8 Severe Errors. EnergyPlus Sizing Error Summary. During Sizing: 210 Warning; 5 Severe Errors. *** EnergyPlus Terminated--Fatal Error Detected. 2574913 Warning; 44 Seve

For the mechanical ventilation controllers, look in the err file to see if there is an issue with those inputs. I don't have that error file handy anymore to look at it. If you don't see any warnings, then don't worry about it. I would, however, try to fix as many warnings as possible.

Thank you rraustad. I had some warning with mechanical ventilation controllers. But the program seems to be now running after changing the min and max SAT (to 55 and 95 resp) in the setpoint manager object that you recommended. Thank you very much for your support. Regards, Biraj