EnergyPlus Surface Temperature
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I am using an EnergyPlus v8.3 file generated from CBECCcom v3d. On running the Propsed model I am getting the following error:
** Severe ** Temperature (high) out of bounds (14545.06] for zone="THERMAL ZONE: LVL04-NW-4037-STORAGE", for surface="LVL04-NW-4037-STORAGE - WALL 302:A"
** ~~~ ** During Warmup, Environment=JACK-NORTHROP-FLD-H ANN CLG 0.4% CONDNS DB=>MCWB, at Simulation time=08/21 00:15 - 00:30
** ~~~ ** Zone="THERMAL ZONE: LVL04-NW-4037-STORAGE", Diagnostic Details:
** ~~~ ** ...Internal Heat Gain [8.611] W/m2
** ~~~ ** ...Infiltration/Ventilation [1.709E-002] m3/s
** ~~~ ** ...Mixing/Cross Mixing [0.000] m3/s
** ~~~ ** ...Zone is part of HVAC controlled system.
** Fatal ** CalcHeatBalanceInsideSurf: Program terminates due to preceding conditions.
Ok, my surface is at 14,505C. That's a problem.
In checking against the baseline model, I am not getting this error. My interior loads match between the two models and are not extreme (~8.6 W/m2 or 0.8 W/ft2; for plug and lights, total). Being that the baseline isn't generating an error, I wouldn't suspect an issue with weather/exterior conditions (and the wall construction is used on many other walls, w/o error).
Now, this is an exterior wall, so I tested deleting this wall from the model; see if this 'fixes the glitch'. Simulation still crashes, but now the error (appears) to have moved to the next surface in the idf file (an interior Ceiling). If this surface is moved within the idf, the error persists. though, the surface temperature is no 21,664C....even hotter. This makes me go back to thinking is an interior load issue....
So, Any ideas or theories on what could be causing a surface to get into this quandary? Or how this error could 'migrate' to the next surface? Any and all ideas welcome...
Does the zone have a floor, and does that floor have some mass to it? If it doesn't try adding one to see if it alleviates the issue.
Can you describe how many surfaces are in the zone and the construction of those surfaces.
is the zone well-formed with surfaces more or less enclosing the space?
What about the constructions for various surfaces (the one that caused the temperature out of bounds error and also any others in the zone)? Something very lightweight/thin could cause a problem like this.
The surface that the error moved to is an interior ceiling, made of metal deck and concrete (storage roof, no finished ceiling). The floor in the space is of similar/same construction. So there is some thermal mass in the space & surface in question. In reviewing the remainder of the surfaces, in total, there are 1 roof (internal), 1 floor (interior), 2 exterior walls, and 1 interior wall. The 'offender' surface was an exterior wall. it was removed (deleted) and the error moved to the interior ceiling....hummm
You said that you checked your model against a baseline model. Does this mean that you started with the baseline input and then made changes to it? If so, what changes did you make? It seems like there is some sort of instability that has been introduced. From what I have seen, this is particularly possible with unusual constructions. The error "moving around" simply means that another surface tripped up the temperature limit. It is highly possible that it is actually not a problem with the exterior or interior surface. Unfortunately, it is hard to tell without seeing your input file(s).
The baseline model (the EnergyPls file, generated from CBECCcom v3d) did run, abet with some other errors - but not the surface temp issue. and no 'fatal' errors. The baseline is/was auto-generated from the proposed model. The issue I am having with surface temps is only in the Proposed model.
I have done some additional/further testing and replaced the constructions with those from the baseline model. Even with these construction (and material) replacements, the error persists....
Strange. I'm not sure what could be causing this but perhaps we can still figure it out. So, if the constructions, materials, and internal gains are the same as the baseline model that is running without producing this error, what are the remaining differences between the baseline input file and the input file that is causing this error?
Well, thats a concern of mine. Seeing as the file is from/part of CBECCcom its going to really take some digging to see. That is not a rip on CBECCcom per se, as much as it wasnt built in E+, so there could be some differences in the translation and I'm not as familiar with the project via this/these inputs...I'll have to dig in and see. This is a large model, so that digging may take some (potentially significant) time. The well gets deeper as this is not the only space with this HVAC type, not the only one with this "configuration" of surfaces. Will keep posting/searching...
Have you sent the model to the CBECC help desk for support on this? Generally, I recommend not modeling surfaces as ceiling, but rather only model floors for spaces and connect to the space below. In translation form SDD to OS, OS will create the reversing surface. Though it has been some time, I have seen this issue before, including the the baseline not having the problem when it has the same surfaces. I found modeling all interior horizontal surfaces as InteriorFloor objects, as opposed to Ceiling objects, alleviated the problem with out of control zone temps.