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# Modelling Underfloor Air Ventilation HVAC in Open Studio

Hello all,

This is a follow up question to the previous question I had about modelling UFAD systems. I placed my supply and return plenums in my model based on some of the Energy Plus examples. I am now trying to figure out how to model the air side HVAC system in Open Studio, but I don't see anything in particular that will allow me to specify floor diffusers, thermostat height, etc...

Has anyone attempted to and successfully modeled an interior UFAD system in Open Studio? Since Open Studio does not transpose HVAC equipment from an imported Energy Plus IDF file, I cannot see how this would be implemented in Open Studio.

I understand how to model this system in the Energy Plus IDF editor, but I would like to model this air distribution system in the .osm file instead of exporting the .osm file into the IDF editor since I would not be able to return back to Open Studio (since it won't import HVAC equipment). Any help is much appreciated!

Jason

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I believe you have done as much setting up as you can do in OpenStudio. It's just a basic air loop with the addition of the supply plenum before the zone diffuser. If you're trying to go into more detail than that the key for you is going to be defining RoomAirModelType object and RoomAirSettings:UnderFloorAirDistribution. Neither of which are supported explicitly supported in OpenStudio or accessible in the GUI for that matter. See here, I feel like everyone neglects this page. Those are the objects that will allow you to define your thermostat height, plume strength and such...In order to use those you'll have to manually add them to the idf for every zone or write an E+ measure.

Unless you have large thermal zones I don't think adding the room air model type is going to make that much of a difference though. The main source of heat transfer change for UFAD systems is the supply plenum and you can capture that without changing the room air model type. You don't have to trust me though, for all you know I could be a compulsive liar!

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Thank you very much for your quick response. That's what I was suspecting about UFAD. I'll try your way and then add the RoomAirModelType to see how it changes the results.

I haven't written a measure for OS, so it may easier for me to go back and forth between OS and E+ for this. Each thermal zone (3 zones) are relatively big at 16,000 sqft, so this could have an impact to the results.

If do get enough time, I will try to write a measure for OS for others to use, but I don't thinking my coding abilities will be up to par :(

( 2016-05-04 10:35:38 -0600 )edit

I just came across this post. I am a beginner as far as open studio and E+ is concerned. I am working on my first open studio model which has an UFAD system. I am trying to find the SupplyPlenum component to drag and drop after the zonesplitter in the airloop but I am unable to find it. I have seen a green trapezoid (supply plenum component) in the open studio airloops. Apologize for the very basic question but where can I find the supplyplenum in the library. Thanks

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Hi, i think you need to create the space and asign a thermal zone to it, that way that would be your plenum.

( 2016-11-02 18:08:34 -0600 )edit

I managed to locate the tab that will add supplyplenum to a thermal zone. However, I am unable to simulate the mixing of return air and conditioned air to get a mixed air temperature of 63 degF. The temperature of the mixed air is no where close to 63 degF and I also dont seem to be controlling humidity very well in the model. Not sure how this is modeled in OS. Is that even possible? I tried to use Dual duct to simulate the mixing but that did not work out.

( 2016-11-03 14:41:46 -0600 )edit

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