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# Modelling large volumes like industrial halls

Hi everyone!

Recently, an architect asked me if I could run a thermal energy simulation for a large industrial hall in order to accurately determine heating and cooling loads for the HVAC systems, because he was asked by his client (they've had some problems with badly sized HVAC systems in the past). I told him that in such cases a building energy simulation probably wouldn't be the best idea, because of the huge air volume on the one hand and typically local heat sources from machines etc. as well as local cooling/comfort requirements on the other hand. With the assumption of perfectly mixed room air, the local effects can't be taken into account the way they should be. So you would have to divide the hall in several parts, both horizontally and vertically in order to try and capture these effects, but I don't really feel comfortable doing that.

My first advice was to conduct a CFD analysis for one or more design conditions as cooling loads in production halls are typically driven by (relatively constant) internal sources.

Has anyone performed energy simulations for such kinds of buildings? What are your experiences? How do you usually deal with dividing a large zone into smaller zones, do you make use of air-walls much? What about vertical stratification?

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I recommend the Room Air Models in EnergyPlus which aimed modeling non-uniform room air temperatures that may occur within the interior air volume of a zone. The Room Air Models contained different air distribution models, for example ThreeNodeDisplacementVentilation used to simulate displacement ventilation. If you had conducted a CFD analysis, define your air model using RoomAir:TemperaturePattern:UserDefined. Refer to Input Output Reference for more information and UserDefinedRoomAirPatterns.idf in ExampleFiles may help you have a better understand of this model.

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Thanks for the hint, I haven't been looking at those models in detail until now. I'll conduct some tests to see how that works out... What about horizontal divisions of large spaces? Do you use the air-wall approach with zone mixing? Or would it be more accurate to use the airflow network with huge openings as an approximation to get the exchange of air between the different parts (somewhat) right?

( 2016-11-17 02:25:52 -0500 )edit

I have the same needs as you, simulating tall buildings (large air volume, large windows), how do you simulate it? The RoomAir model can only set the temperature gradient, and the average temperature still needs to be calculated by energyplus (energyplus is not accurate for large air volume calculation) )

( 2019-09-11 21:02:54 -0500 )edit