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How to add different types of loads through an OpenStudio Measure

asked 2022-02-01 08:50:01 -0500

Vasco Figueiroa's avatar

updated 2022-03-15 08:56:18 -0500

Hi,

I want to add an internal load to my OpenStudio model that isn't a Light, Electric equipment, etc definition. Could I write an OpenStudio measure which calculates the heat flux of that load based on constants, user defined arguments and weather data, and then add it to the collection of internal loads of the model?

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answered 2022-02-01 17:22:10 -0500

What you are describing can be done with Other Equipment described here in the input output reference.

I'm not aware of a measure that does this, but this measure that adds electric equipment to a space could be a good starting point. A few notes below.

  1. This measure is for electric equipment but could easily be switched to other equipment
  2. This measure assumes that the load definition and schedule exists and it just assigns them. This requires some work to be done in the seed model to add objects you may want to include. It could be extended to make the definition but would require more user arguments. Making a schedule on the fly isn't as easy unless it is very simple.
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Thanks for your response! The Other Equipment type of load matches my needs, but I'm not sure how I gather weather data for the measure script that changes with each timestep of the simulation. In the weather file class reference, I can't find any function related to any type of radiation. I'm not even sure if this is possible, as I don't know if an OpenStudio Measure can be run for each simulation timestep.

Vasco Figueiroa's avatar Vasco Figueiroa  ( 2022-02-02 09:03:20 -0500 )edit

Sorry I missed the part about the load changing based on weather file. If you can make a fractional CSV ahead of time that can be used as a schedule for the load. Can you describe the use case a bit more. I'm wondering if a heat transfer surface exposed to outside can more directly do this. How is this load in reality being impacted by the weather, and can that be more directly modeled.

David Goldwasser's avatar David Goldwasser  ( 2022-02-02 11:43:04 -0500 )edit

(1) Regarding the use case, I want to model a greenhouse and take into account the thermal load of the plants inside the greenhouse. A couple of interesting suggestions came up while researching, 4th comment from the 1st answer and 3rd paragraph from the last answer, but both require to know a priori the thermal load of the plants. There is also the GreenRoof material, which only works for the outmost layer of roofs.

Vasco Figueiroa's avatar Vasco Figueiroa  ( 2022-02-02 11:58:17 -0500 )edit

(2) Related question. I had the idea of redoing and recompiling the GreenRoof material source code, but that would take me a huge amount of time and I'm not sure if the binaries of a standalone EnergyPlus installation is any different from the EnergyPlus integrated into OpenStudio. Meanwhile I encountered a simple enough model (Equations 7,10 and 11) which describes the heat flux from the evapotranspiration based on net radiation and the...

Vasco Figueiroa's avatar Vasco Figueiroa  ( 2022-02-02 12:04:09 -0500 )edit

(3) heat flux from the ground. Net radiation is probably obtainable from the weather data (don't know how) and I believe the heat flux is a value calculated for each timestep (not sure how to obtain it, output variables related to surfaces are only Inside and Outside Temperatures). The Other Equipment type of load would have a Design Level heat flux, which would be the maximum value for the whole year and then a fractional schedule that would be defined as the division between the current evapotranspiration and this maximum value. Sorry for the wall of text!

Vasco Figueiroa's avatar Vasco Figueiroa  ( 2022-02-02 12:19:35 -0500 )edit

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Asked: 2022-02-01 08:50:01 -0500

Seen: 1,725 times

Last updated: Feb 01 '22