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2020-04-26 17:10:16 -0500 asked a question Citable ZoneVentilation:WindandStackOpenArea parameters

Citable ZoneVentilation:WindandStackOpenArea parameters What's a good reference for reasonable parameters for occupants

2020-04-09 15:35:10 -0500 asked a question Python API Workaround for EnergyPlus 9.3

Python API Workaround for EnergyPlus 9.3 Is there an easy workaround to use the new Python API with EnergyPlus 9.3 for f

2020-04-07 15:26:59 -0500 commented question Utilities Tab in e+9.3 launcher

I have the same problem on windows. I added an issue on github. https://github.com/NREL/EnergyPlus/issues/7910

2020-04-07 15:26:41 -0500 commented question Utilities Tab in e+9.3 launcher

I have the same problem. I added an issue on github. https://github.com/NREL/EnergyPlus/issues/7910

2020-03-31 22:11:19 -0500 edited question VRF with constant curves has COP < 1.0

VRF with constant curves has COP < 1.0 !!!THIS ISSUE SHOULD BE FIXED IN ENERGYPLUS 9.3!!! I took the DOAtoVRF.idf ex

2020-03-02 17:45:42 -0500 marked best answer Chiller loop getting to 322C in first timestep of design day and causing Severe error

I'm having some difficulty running a simulation. The error is below. There's no reason why the chiller loop should be this hot. I think it's just a numerical error because it's during the simulation of the first time step of a design day, the previous design days simulate just fine, and I bet the rest of the simulation would run just fine if I could get EnergyPlus to ignore the high temperature for a couple time steps. Oddly, I can get the error to go away by changing the storage capacity of the thermal energy storage ice tank that the chiller is feeding into. Any ideas on how I could get energyplus to ignore the high temp for just a little bit?

Workaround below, but still no solution.

** Severe  **
Plant temperatures are getting far too hot, check controls and relative loads and capacities
During Warmup, Environment=TORRANCE-MUNICIPAL ANN CLG 1% CONDNS DB=>MCWB, at Simulation time=08/21 00:04 - 00:06
PlantLoop Name (SupplySide)= CHILLED WATER LOOP PRIMARY WATER LOOP ICE TANK CHILLER HEAT EXCHANGER HALF
PlantLoop Setpoint Temperature=-5.0 {C}

PlantLoop Outlet Node (SupplySide) "CHILLED WATER LOOP CHW PRI SUPPLY OUTLET" has temperature=322.3 {C}
PlantLoop  Inlet Node (SupplySide) "CHILLED WATER LOOP CHW PRI SUPPLY INLET" has temperature=-4.5 {C}


Post Script
I just tried the obvious idea of changing the time step. A timestep of 10 minutes gave the 322C error, a timestep of 1 minute gave a 491C error, and a timestep of 30 minutes gave a 359C error.
Post Post Script
I came up with a workaround. I increased the Maximum Loop Temperature field of the PlantLoop object to 400C and got these errors for a simulation running from 5/1 to 10/1.

Warning GetSpecificHeatGlycol: Temperature out of range (too high) for fluid [ETHYLENEGLYCOL40PERCENT] specific heat 
   *************  **   ~~~   **   This error occurred 718 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=595.421006 {C}  Min=127.188615 {C}
   *************
   *************  ** Warning ** GetDensityGlycol: Temperature out of range (too high) for fluid [ETHYLENEGLYCOL40PERCENT] density **
   *************  **   ~~~   **   This error occurred 144 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=595.421006 {C}  Min=127.191025 {C}
   *************
   *************  ** Warning ** Plant loop exceeding upper temperature limit, PlantLoop="CHILLED WATER LOOP PRIMARY WATER LOOP ICE TANK CHILLER HEAT EXCHANGER HALF"
   *************  **   ~~~   **   This error occurred 2 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=521.753501


I also looked the System Node Temperature for the node that was getting to 322C before and it does not report a termperature outside -10C to 10C. So looks like something's wrong with energyplus, possibly as simple as an overly aggressive error condition.

2020-03-02 17:35:08 -0500 commented answer AirflowNetwork and Construction:AirBoundary interaction?

@sspielman I'm not sure what you're asking, so I'll make a concrete example. There are conditioned zones A and B in the

2020-03-02 17:34:33 -0500 commented answer AirflowNetwork and Construction:AirBoundary interaction?

@sspielman I'm not sure what you're asking, so I'll make a concrete example. There are zones A and B in the IDF. The sin

2020-03-02 17:29:02 -0500 commented answer Can the AirFlowNetwork handle two AirLoops serving the same zone?

@sspielman I don't think I can add any ZoneHVAC:* objects to condition a zone since the ZoneHVAC:* objects require the "

2020-02-28 12:29:58 -0500 asked a question AirflowNetwork and Construction:AirBoundary interaction?

AirflowNetwork and Construction:AirBoundary interaction? I'm modeling a building that has two airloops serving a single

2020-02-28 12:07:01 -0500 commented question interior air walls for splitting nonconvex zones

@EngFranc What exactly is energyplus unable to handle in nonconvex zones? I know there are some problems with simulating

2020-02-28 12:03:12 -0500 edited question Model vertical helical ground heat exchanger in EnergyPlus

Model vertical helical ground heat exchanger in EnergyPlus We have an experimentally validated model of a helical ground

2020-02-28 11:58:06 -0500 commented question Is there a way to Model a Vertical Helical shallow GSHP (Please Refer Fig.)for a residential building in EnergyPlus ? I have already tried Ground Heat Exchanger: Vertical Properties by utilizing G-function values from my analysis

@Archan Shah I was working on this exact problem. The answer is no. EnergyPlus does not have a way to model a vertical h

2020-02-28 11:56:59 -0500 commented question Is there a way to Model a Vertical Helical shallow GSHP (Please Refer Fig.)for a residential building in EnergyPlus ? I have already tried Ground Heat Exchanger: Vertical Properties by utilizing G-function values from my analysis

@Archan Shah I was working on this exact problem. The answer is no. EnergyPlus does not have a way to model a vertical h

2020-02-28 11:56:00 -0500 edited question Model vertical helical ground heat exchanger in EnergyPlus

Model helical ground heat exchanger with EnergyPlus U-tube model We have an experimentally validated model of a helical

2020-02-28 11:55:18 -0500 answered a question Can the AirFlowNetwork handle two AirLoops serving the same zone?

The answer appears to be no. With no responses I did a little test by trying to add a ZoneHVAC:UnitHeater to the Airflow

2020-02-28 11:32:46 -0500 asked a question DOASDXCOIL_wADPBFMethod_NoReturnPath.idf Where does the excess air go?

DOASDXCOIL_wADPBFMethod_NoReturnPath.idf Where does the excess air go? In the DOASDXCOIL_wADPBFMethod_NoReturnPath.idf e

2020-02-28 10:48:07 -0500 marked best answer Model vertical helical ground heat exchanger in EnergyPlus

We have an experimentally validated model of a helical ground heat exchanger, like this.

image description

A PhD student spent a few years working on this project, and the next step is for him to model it in EnergyPlus. We have a major problem though since the closest object in EnergyPlus is the U-tube and the results don't agree. We're pretty sure the discrepancy comes from the grout in the borehole lying between the dirt and U-tube, versus the helix which is right against the edge of the borehole. The PhD student found that the mean water temperature in the helix is almost the same as the mean borehole wall temperature and the grout plays almost no role.

The PhD student is freaking out a little bit, so I'm trying to help him finish. We already tried making an impossibly conductive grout material but that is causing very bad looking errors in EnergyPlus. I found the GroundHeatExchangers.cc file, which is very readable, and I think I could plausibly alter the code and recompile EnergyPlus to set fluid temperature based on the borehole wall temperature, but that's not an appealing solution. There's cosimulation possibilities with matlab, but can those alter things like water temperatures in plantloops?

Does anyone have any ideas how to remedy this? Doesn't have to be clean, just has to work.

POST SCRIPT
Just as a reminder to soil fluctuation, here are ground temperatures from EPW files for El Paso, TX and Honolulu, HI. The ground temperatures vary significantly at different depths without a heat exchanger. With a heat exchanger, the ground temperatures will change. This is taken account of in the GroundHeatExchangers.cc code. In the case of the U-tube, the G-functions are used to calculate the boundary temperature between the dirt and grout at the borehole wall. Part of that computation uses many previous iterations of the simulation because the ground temperatures do not stay constant. In fact, it can take months after turning off ground heat exchanger for the ground temperatures to go back to normal. After calculating the borehole wall temperature, looks like the code uses a finite element method to calculate the grout temperature at the U-tube pipe wall. Then the model actually takes into account the heat propagation through the pipe wall, and then fluid temperature is calculated. This is not a trivial problem. image description image description

2020-02-28 10:48:00 -0500 answered a question Model vertical helical ground heat exchanger in EnergyPlus

We ended up going with the matlab and energyplus cosimulation using this matlab toolbox on github. The toolbox is able t

2020-02-27 19:54:47 -0500 marked best answer Utility Tariff not calculating midPeak the first month

I have a time of use electricity schedule and there's a couple weird things going on with it. First, the summer blocks are being used a month early, but at the same time the summer midPeak energy is not being calculated in that first erroneous month, but is being calculated correctly for the months after. Here's a google drive link to the file. I know it's probably a silly mistake on my part, but there aren't that many places to look for errors. There's the season schedule, TOU schedule, Utility Tariff and Block objects. Any idea what's going on?

The season schedule definitely has summer starting 6/1 too.

Schedule:Compact,
    Electricity Season Schedule,  !- Name
    Any Number,              !- Schedule Type Limits Name
    Through: 5/31,           !- Field 1
    For: AllDays,            !- Field 2
    Until: 24:00,            !- Field 3
    1,                       !- Field 4
    Through: 9/30,           !- Field 5
    For: AllDays,            !- Field 6
    Until: 24:00,            !- Field 7
    3,                       !- Field 8
    Through: 12/31,          !- Field 9
    For: AllDays,            !- Field 10
    Until: 24:00,            !- Field 11
    4;                       !- Field 12

image description

The only Block with midPeak is during Summer, so I can't figure it out. (The writing is big enough to read if you open the image in a new tab.)

image description

2020-02-27 19:54:45 -0500 commented answer Utility Tariff not calculating midPeak the first month

@JasonGlazer We ended up making summer start a day later, and that seems to have fixed it. Thanks!

2020-02-24 10:44:28 -0500 commented question Utility Tariff not calculating midPeak the first month

@JasonGlazer Any luck with this?

2020-02-21 19:09:38 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@JKavanaugh I do not.

2020-02-21 16:47:43 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@JKavanaugh Sorry for the confusion. Yes, the experimental data comes from the helical heat exchanger shown in the photo

2020-02-21 16:18:38 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@JKavanaugh I know you're trying to be helpful, but these models are fundamentally different. The temperature of the dir

2020-02-21 12:20:36 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@anchapin 1) The slinky is a way different model from a vertical bore. It just won't work.2) We do have the correct resp

2020-02-21 12:20:25 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@JKavanaugh The picture is in the post is actually from the experiment. You can see the complex where out lab is located

2020-02-21 12:19:53 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@anchapin 1) The slinky is a way different model from a vertical bore. It just won't work.2) We do have the correct resp

2020-02-21 11:24:47 -0500 commented answer Model vertical helical ground heat exchanger in EnergyPlus

@JKavanaugh The picture is in the post is actually from the experiment. You can see the complex where out lab is located

2020-02-21 11:19:57 -0500 edited question Model vertical helical ground heat exchanger in EnergyPlus

Model helical ground heat exchanger with EnergyPlus U-tube model We have an experimentally validated model of a helical

2020-02-20 18:27:10 -0500 asked a question Model vertical helical ground heat exchanger in EnergyPlus

Model helical ground heat exchanger with EnergyPlus U-tube model We have an experimentally validated model of a helical

2020-02-19 16:48:09 -0500 asked a question Can the AirFlowNetwork handle two AirLoops serving the same zone?

Can the AirFlowNetwork handle two AirLoops serving the same zone? I am modeling some multifamily housing with a common a

2020-02-14 15:41:49 -0500 edited question Utility Tariff not calculating midPeak the first month

Utility Tariff not calculating midPeak I have a time of use electricity schedule and there's a couple weird things going

2020-02-14 15:30:40 -0500 edited question Utility Tariff not calculating midPeak the first month

Utility Tariff not calculating midPeak I have a time of use electricity schedule and there's a couple weird things going

2020-02-14 15:29:45 -0500 commented question Utility Tariff not calculating midPeak the first month

@JasonGlazer You know you're way around the Tariff objects, right? Any idea what's going on?

2020-02-14 15:25:24 -0500 asked a question Utility Tariff not calculating midPeak the first month

Utility Tariff not calculating midPeak I have a time of use electricity schedule and there's a couple weird things going

2020-02-12 13:38:32 -0500 edited question Example AirFlowNetwork Drawing for IDF

Example AirFlowNetwork Drawing for IDF Is there a drawing anywhere corresponding to an IDF of how all the stuff in the A

2020-02-11 15:22:22 -0500 commented question Example AirFlowNetwork Drawing for IDF

The original issue I posted has been closed. The new issue is https://github.com/NREL/EnergyPlus/issues/7762 posted by @

2020-02-11 15:21:53 -0500 commented question Example AirFlowNetwork Drawing for IDF

The original issue I posted has been closed. The new issue is https://github.com/NREL/EnergyPlus/issues/7762 posted by @

2020-02-11 10:36:43 -0500 commented answer Example AirFlowNetwork Drawing for IDF

@Jason DeGraw I did actually, but at the same time I won't be using the full power of the AFN objects. The goal of the p

2020-02-10 16:02:29 -0500 commented question Example AirFlowNetwork Drawing for IDF

I have added an issue for EnergyPlus. https://github.com/NREL/EnergyPlus/issues/7756

2020-02-10 15:53:14 -0500 edited question Example AirFlowNetwork Drawing for IDF

Example AirFlowNetwork Drawing for IDF Is there a drawing anywhere corresponding to an IDF of how all the stuff in the A

2020-02-10 15:21:58 -0500 commented answer Example AirFlowNetwork Drawing for IDF

@Aaron Boranian I'm attempting to draw out the relationship between the AirLoop and the AirFlowNetwork and I'm finding e

2020-02-10 15:21:24 -0500 commented answer Example AirFlowNetwork Drawing for IDF

@Jason DeGraw I'm attempting to draw out the relationship between the AirLoop and the AirFlowNetwork and I'm finding eve

2020-02-10 13:51:45 -0500 edited question Example AirFlowNetwork Drawing for IDF

Example AirFlowNetwork Drawing for IDF Is there a drawing anywhere corresponding to an IDF of how all the stuff in the A

2020-02-10 13:49:01 -0500 edited question Example AirFlowNetwork Drawing for IDF

Example AirFlowNetwork Drawing for IDF Is there a drawing anywhere corresponding to an IDF of how all the stuff in the A

2020-02-10 13:20:38 -0500 edited question Example AirFlowNetwork Drawing for IDF

Example AirFlowNetwork Drawing for IDF Is there a drawing anywhere corresponding to an IDF of how all the stuff in the A

2020-02-10 13:14:20 -0500 edited question Example AirFlowNetwork Drawing for IDF

Example AirFlowNetwork Drawing for IDF Is there a drawing anywhere corresponding to an IDF of how all the stuff in the A

2020-02-10 13:11:46 -0500 commented answer Example AirFlowNetwork Drawing for IDF

@Jason DeGraw Thank you for the information about the uncaught node issue. I'll try and modify the example IDF and see i