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How do I add a previously simulated building load (CHW and HW) to another building which contains the central plant?

asked 2016-02-09 12:21:01 -0500

NickC gravatar image

updated 2016-02-09 12:28:54 -0500

Hello UA; I've been working on how best to enter previously simulated building loads onto the main central plant. I know the heating and cooling loads each building requires from the plant loop, along with their flowrate demands, for a typical year. My central plant has the LoadProfile:Plant object inserted in place of the buildings.

What ways do you know of to get the building load wattage and flowrate into the LoadProfile:Plant object? I REALLY don't want to generate a day-by-day schedule for the whole year...

Associated Questions (I'd say) 1 2 3

Some Details: Building configuration image description

and Buildings 1-3 have already been simulated with district heating/cooling on their CHW and HW building loops. image description image description

Lastly, the main building central plant (to be simulated) has LoadProfile:Plant objects for Building 1-3 on both the CHW and HW loops. Shown below are the primary and a representative secondary loop. Primary HW Loop Secondary HW Loop for Bldg 1 & 2

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answered 2016-02-09 13:25:13 -0500

updated 2016-02-09 13:27:28 -0500

As you mention, the LoadProfile:Plant object wants an hourly load schedule [in W], a peak flow rate, and an hourly normalized flow rate schedule [0-1]. Positive values for the load indicate a heating load, and negative values indicate a cooling load. The flow rate schedule is a fractional schedule of the design flow rate entered. It's possible to pull hourly flow rates from the original model and use them in the profile schedule, however I have found greater success (and less headache) using the hourly load schedule to create a normalized hourly flow schedule by calculating the flow rate from the hourly load assuming a constant delta-T.

Unfortunately OpenStudio does not support the Schedule:File object that is native in EnergyPlus, so the only way to create a custom 8760 hourly schedule in OpenStudio is to create one manually in the interface (grueling) or use a measure to create one automatically.

The post HERE contains the syntax needed to execute this as a ruby script. I repurposed this just the other day to build a measure that will create a custom hourly OpenStudio schedule from the values in a CSV excel file. It's not pretty but it does create a custom 'Fixed Interval' schedule with the interval set to hourly and unique values for each hour.

If you are savvy enough to turn the snippets from the post above into a measure, I would suggest trying that. If not, I may be able to share the measure I created but buyer beware (it's a little rough around the edges for external use).

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I saved a version of the measure HERE. You can unzip the file and place the whole folder in your measure directory (typically C:\Users\[username]\OpenStudio\Measures. It should then be accessible in the OpenStudio application under Components & Measures > Apply Measure Now > Whole Building > Whole Building Schedules

Lyle K gravatar imageLyle K ( 2016-02-09 14:10:58 -0500 )edit

Thanks Lyle! I do some programming in C++ and Matlab, but not Ruby (yet). However, I DO know a couple of savvy software types and will run it all by them to see what we can come up with. I'm planning to start with your measure and see how it all goes. If we end up making modifications, I'll repost the file and would appreciate your thoughts on that as well. Cheers! -N

NickC gravatar imageNickC ( 2016-02-09 14:55:41 -0500 )edit

@Lyle K I followed your instructions re: unzipping the measure (lk_create_8760_schedule.zip) and placing it into '/Users/nicholascardwell/OpenStudio/Measures' directory. After doing so, I don't see the measure in the OS "Apply Measure Now" under "Whole Building Schedules". Is there another step I should be doing? I also verified my measure path in OS, and it is where your measure is now located.

NickC gravatar imageNickC ( 2016-02-11 14:11:45 -0500 )edit

Update @Lyle K: changing the OS version text in the *.xml file gets the measure to show up under the OS "Apply Measures Now" " <identifier>1.9.0</identifier> <min_compatible>1.9.0</min_compatible>"

However, running the meas. doesn't result in a new schedule yet. Advanced output is as follows: " Script executing from: /private/var/folders/8d/r3mr98dj3gzg2pvmdvg6m52m0000gp/T/OpenStudio.l16458/ApplyMeasureNow/UserScript Found argument 'schedule_name' with value 'aaa'. Found UserScript 'LK Create 8760 Schedule'. result = true Processed 1 base script and 0 merged scripts "

NickC gravatar imageNickC ( 2016-02-11 18:01:12 -0500 )edit

Update 2 @Lyle K: Correction, the new schedule is there! User error; I was previously checking under the "Schedules" tab and, not seeing anything, assumed something was wrong. Opening the *.osm file with a text editor proved that the new schedule was there. It seems the type of schedule (OS:Schedule:FixedInterval) doesn't show up under the "Schedules" tab, but is accessible through the LoadProfile:Plant object.

NickC gravatar imageNickC ( 2016-02-12 09:40:16 -0500 )edit

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Asked: 2016-02-09 12:21:01 -0500

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Last updated: Feb 09 '16