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Modelling radiating panels in roof?

asked 2015-01-19 13:58:56 -0500

Waseem's avatar

updated 2015-07-10 21:31:17 -0500

Hi All,

I am trying to model a radiant panel heating system. There is possibility of modelling it by using ZoneHVAC:LowTemperatureRadiant:VariableFlow object. I think in this method EnergyPlus considers that the InternalSource's area equal to the area of the surface (e.g. roof areas). Is this the right approach or I have to divide the roof into several area and then considering small area as InternalSource? I have already modeled the geometry so the second option can be challenging, is the first approach is equal to the second approach? Please see the pic to see below to find how the panels are distributed,and the whole surface is radiating surface.

Also, in internal source we don't really model the material of the heating panels e.g. Aluminum panels. We just consider the tubing distance and spacing etc, will that make a difference (Panels in Pink red and pipes in pink)?

Last thing, how can we control the LowTemperatureRadiant:VariableFlow? Can we control the supply flow in a zone to control the indoor air temperature?

Panels in Pink red and pipes in pink


Kindest Regards


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This is a duplicate question, is it not?

Benjamin's avatar Benjamin  ( 2015-01-19 14:19:47 -0500 )edit

Hi @Benjamin, it is not the same. It is from another direction or more detailed. Thanks

Waseem's avatar Waseem  ( 2015-01-19 14:32:23 -0500 )edit

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answered 2015-01-19 15:02:06 -0500

LowTemperatureRadiant:VariableFlow is appropriate for this application. It is important that the active surface area be realistic. I would recommend using door objects to model the radiant panels. (Contrary to what the current Input Output Reference states, radiant systems may be embedded in door subsurface - this will be fixed for the next release) By using subsurfaces, you can easily apply the radiant systems to a smaller surface area.

I am puzzled by the statement " in internal source we don't really model the material of the heating panels e.g. Aluminum panels. We just consider the tubing distance and spacing etc." The internal source object requires at least two material layers, one on either side of the source. Are you saying you are including all of the material layers except the aluminum? That is probably OK for this application, a minor effect in the overall heat transfer from the fluid to the zone.

LowTemperatureRadiant:VariableFlow has fields for specifying the controls. It has several control options, including zone air temperature.

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Yes, that is correct.

MJWitte's avatar MJWitte  ( 2015-01-22 13:58:25 -0500 )edit

@MJWitte So will the ground floor room's radiant penal will provide heat/energy to top floor room as the construction is mirrored? I am sorry I am taking too much of your time. Thanks

Waseem's avatar Waseem  ( 2015-01-23 09:44:01 -0500 )edit

Yes, it will heat both spaces. The portion that goes to the upper zone will depend, of course, on the material layers that are above and below the source.

MJWitte's avatar MJWitte  ( 2015-01-23 13:31:21 -0500 )edit

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Asked: 2015-01-19 13:58:56 -0500

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Last updated: Jan 19 '15