Mehrdad Vojdani's profile - activity

Dear Developers and Engineers,

Our research group is going to perform an energy performance enhancement study on existing buildings. We found DOE commercial buildings suitable for our case study since it provides so many comparison opportunities.

Our study does not concern with HVAC equipment and control but we need it to be and work based on the latest version of ASHRAE 90.1. We decided to go with OpenStudio measures which simulate the mechanical (HVAC) system as well as constructions. I don't know how these measures work and whether is there any validation process or not. But according to this video, the measure named "Create DOE Prototype Building" was chosen.

As we were checking the simulation results, we found out some issues that I need to share with you (LargeOffice-ASHRAE 169-2006-2A):

• A high amount of unmet hours was observed. I believe it can be due to low temperature tolerance. According to Matt Larson's answer to this question I changed the temperature tolerance to 0.556C. But it didn't solve the problem. here are some pictures of the Openstudio results and here is the results of unmet hours troubleshooting. According to troubleshooting, a temperature difference of 2.5 F would reduce unmet hours significantly. Isn't it more of a reporting problem than an operational problem? Any idea to solve it?
• OpenStudio didn't provide any warnings concerned with the HVAC sizing or simulation. But Energyplus err file contained plenty of warnings that worried us. here is the IDF file and err. To be specific, warning associated with plant sizing and simulation seems pretty serious. Since we are not HVAC engineers, we would appreciate any advice to ignore or fix these issues.

Regards.

PS:

I believe I found some problems with the measure. In the IDF file, I found that CLGSETP_SCH_NO_SETBACK Summer Design Day with some setbacks during unoccupied hours is used for sizing calculation. While CLGSETP_SCH_NO_SETBACK Default and CLGSETP_SCH_NO_SETBACK Default|WntrDsn|Sat|Wkdy Day with no set back is used for simulation. I also checked with IDF files provide here and I think I'm right about it.

In case of having multiple chillers in parallel in chilled water plant loop, some simple control strategy could be considered:

Uniform: In this control strategy, each chiller would make same load part. Sequencing: In this control strategy, the first chiller would work at its highest PLR and then the other chiller and the other and...

Currently, I am working with OpenStudio. I chilled water loop tab, there is a part for controlling. An availability manager part can be seen but, I don't know how to use it and I don't know if it's capable of preforming mentioned control strategies.

1- Can anyone help me with this?

2- I have another question related to this. Is it possible in each timestep we determine how many chillers to use and what control strategy to use?

Hi,

I know EnergyPlus already contains ice storage and cold water storage tank. In my research, I need to study and test phase change material like paraffin waxes or bioPCMs. Is there any way to change ice storage tank properties in order to change its behavior to the PCM storage tank? if not, I would appreciate any help!

If it's possible for you, please share any document (theses, paper, etc) that provides (detailed) information about coupling EnergyPlus and MATLAB. I already know about bctvb main tutorial. I need some more practical, case study and exemplary ones.

I have a problem with the geometry of the DOE reference building. I loaded the model by OpenStudio measure and in the Geometry tab of OpenStudio, it shows only three floors! I realized that the model multiplies middle zones by 10 to simulate floors between top and basement floor.

As long as there is no lighting study, Is it valid to do such a thing? Is it enough that the middle floor's ceiling has an appropriate boundary condition?

I'm using the default openstudio curve setting for chillers in DOE reference buildings simulation to cool an ice storage tank. I have to set chiller output temperature to negative values (e.g. -5). The simulation completed successfully but here is a warning that concerns me:

Chiller:Electric:EIR = Chiller:  Integrated Part Load Value (IPLV) calculated is not at the AHRI test condition.

I'm not familiar with IPLV variable and how important it is... This chiller is not specially selected for ice-making applications and that might be a problem. Since I'm studying a non-standard cooling system, Is this warning important or not?

@Julien Marrec, Thank you. I tried ramping down the setpoint but that couldn't help. Here is a detailed output variable

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works with just a fe

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works with just a fe

Trouble getting variable handle in PythonPlugin I'm having trouble getting some variable handles using PythonPlugin in e

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works without any wa

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works without any wa

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works without any wa

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works without any wa

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus works without any wa

Pumping system / Plant Convergence issue The following configuration of cooling loops in energyplus worrks without any w

Why does my simulation terminates in the middle of simulation (7h month)) Hi everyone, I am having the following error.

I using primary and secondary loops to provide cooling in my case. A heatexchanger:fluidtofluid is used to connect these two loops. The problem is that the primary loop, which contains water/glycol as the working fluid, cools the heat-exchanger with a supply temperature of -4. I don't want that heat-exchanger outlet on the supply side of heat-exchanger flow the negative temperature. Because the fluid in the secondary loop is pure water. I'm using an ideal heat exchanger.

The green temperatures are my desired temperatures and the red ones with plenty of error are ones that I get!

Can anyone tell me why my open studio model in SketchUp keeps going white? I never save through SketchUp and only open i

I think when you start to work with the openstudio application, you are actually adding some objects that the openstudio

Hi @kimiya, in my opinion, each CHP system should be optimized separately. There would be no point in optimization if yo

Just to be clear, output:variable reporting frequency doesn't matter for the plugin.

I'm having trouble getting some variable handles using PythonPlugin in energyplus. I wonder if all the variables listed in the *.rdd output file are available for the python plugin ...

For example here is what I got in the *.rdd file:

Output:Variable,prm,Plant Supply Side Cooling Demand Rate,hourly; !- HVAC Average []

and here is what I used in my python script to get the handle:

self.sensors["demand rate"] = self.e.get_variable_handle(
              state, "Plant Supply Side Cooling Demand Rate", "prm")

Unfortunately, the API returns -1 value for this variable and some other variables. I can't figure out what's the problem. It seems that all the variables listed in the *.rdd file cannot be handled by PythonPlugin. If I'm right, how can one identify available variables(sensors) for each model? I hope that you can help me with this.

P.S.

self.e = self.api.exchange

You need to read the EMS manual. No one here would not do that for you :) Also, I recommend you to ask you bcvtb related

How can I get unmet hours during the simulation? In order to reduce the computational load during the optimization of my

How can I get unmet hours during the simulation? In order to reduce the computational load during the optimization of my

[bcvtb],inputs and outputs energyplus and systemcommand Hello I am trying to connect idf to system command (Compiled cpp

Here is a solution my friend. After autosizing components in the plant loop that you intend to use your virtual load, re

Here is a solution my friend. After autosizing components in the plant loop that you intend to use your virtual load, re

@Julien Marrec, Where should I use it? I didn't get your point. Actually, I got the idea of the virtual load from a pape

I found a problem with the curve input/output in my model. The curve is used for chiller performance (EirFTemp). I have reported the following variables:

Output:Variable,Water Cooled Chiller EItoCoolingOutputRatioFofT,Performance Curve Input Variable 1 Value,timestep; !- HVAC Average []
Output:Variable,Water Cooled Chiller EItoCoolingOutputRatioFofT,Performance Curve Input Variable 2 Value,timestep; !- HVAC Average []
Output:Variable,Water Cooled Chiller EItoCoolingOutputRatioFofT,Performance Curve Output Value,timestep; !- HVAC Average []

(since I'm using Chiller:Electric:EIR object, variable 1 is chiller outlet temperature and variable 2 is chiller's condenser inlet temperature) I need to modify the curve output by EMS, so I decided to use sensor variables (chiller outlet temperature & condenser inlet temperature). As you can see in below, I realized the curve is using input variables much different from sensor variables that I'm receiving from energyplus:

Columns with same color should have a same value (at least with a time lag!). But they are much different specially for the chiller outlet temperature. Why the input 1 of the curve is different from chiller outlet temperature?! Where does it come from?!

Update: I should mention that it happens mostly when the chiller outlet temperature setpoint is negative (e.g. -5).

Update (following my response to Julien): I think I narrowed down the problem. The IceStorage-Series-ChillerUpstream.idf example file works fine because there is no night time load on the secondary side of the loop. I changed the night time setpoint. So chiller should charge (with -5 setpoint) & also provide cooling for the secondary loop (with a 6.7 setpoint). Also, the ice storage outlet has a 6.7 C setpoint all the time. Since there are a two-way common pipe and separate pumpings on the primary and secondary side, having both charging and cooling can't be a problem! Here is files where I compared EnergyPlus example with modified one with nightload.

Thank you @julien Marrec for your time. I really appreciate it. You are absolutely right about capacity function of temp

Hi @bbrannon4, I hope you're doing well. I wonder if you have any ice-making chiller curve data available. I would reall

Hi @bbrannon4, I hope you're doing well. I wonder if you have any ice-making chiller curve data available. I would reall

Dear @hj630 , I am working on a similar project with academic goals. Can you share your experience with Ice storage mode

Hi @bbrannon4, I hope you're doing well. I wonder if you have any ice-making chiller curve data available. I would reall

Hi bbrannon4, I hope you're doing well. I wonder if you have any ice-making chiller curve data available. I would really