Re: [EnergyPlus_Support] interior walls in a one zone model

[Jeremiah Crossett <jcrossett@xxxxxxxxxxxxxxx>]

Walls that are ?Adiabatic? in EnergyPlus still store and release heat.  They have the same boundary conditions on both faces. When those conditions are varying, then heat will flow in and out of the wall and get stored and released in the thermal mass.  

Brent-  

Thanks for correcting my mistake, however I am now curios if you could please elaborate?

So are you speaking of using the outside boundary condition of "zone" or "surface" or "adiabatic" or any/all of these?

My understanding was that if the boundary condition was "zone"  that it store and release heat and would have the same  air temp as the actual-zone. And that "surface"  boundary condition would have a mock-surface with the same radiant temp as the surface. 

I figured that adiabatic was like one might find in a dictionary --adiabatic (not comparable)

• (physics) (of a thermodynamic process) Occurring without gain or loss of heat. 

Thanks-

 

Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions

120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951

www.phasechange.com 

  

On Fri, Jan 11, 2013 at 9:33 AM, Griffith, Brent <brent.griffith@xxxxxxxx> wrote:

 

There is some incorrect information here.  Walls that are ?Adiabatic? in EnergyPlus still store and release heat.  They have the same boundary conditions on both faces. When those conditions are varying, then heat will flow in and out of the wall and get stored and released in the thermal mass.   For a true adiabatic zone boundary, just omit the surface.   

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jeremiah Crossett
Sent: Friday, January 11, 2013 9:46 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] interior walls in a one zone model

 

 

Niko, 

Typically adiabatic walls are not used to account for thermal inertia, as they are are adiabatic their only function to end a zone at the point where it would meet another zone. For instance one might use an adiabatic surface if they wanted to do a shoebox model of a single zone separated from a larger building. 

 

The object that is designed to account for "thermal inertia" is called: "Internal Mass" and can be found in the "Thermal Zones and surfaces" section of idf editor.

Here is a what the inputs can look like:

 

Name Phase Change Internal Mass

Construction Name BioPCM_LightWeightWall

Zone Name   Zone1

Surface Area            100

 

 

 

 

Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions

120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951

www.phasechange.com 

  

 

 

 

 

On Fri, Jan 11, 2013 at 6:17 AM, niko_heeren <nheeren@xxxxxxx> wrote:

 

Dear community

I am a little confused about internal walls. For a 1 zone model of a single family building I want to introduce the internal walls in order to correctly account for their thermal inertia.

What is the correct way to input an interior wall within a zone?
Can / should I use the object Wall:Adiabatic?

The interior wall consists of three layers: plaster/insulation/plaster

The I/O reference of energyplus confuses me a little: On page 176 it says to the object Walls:Detailed:
"Only the inside face of the surface will exchange heat with the zone (i.e. two adiabatic surfaces are required to model internal partitions where both sides of the surface are exchanging heat with the zone)."

On page 156 on Walls:Adiabatic it says:
"Regardless of location in the building, the "full" construction (all layers) is used."

Any help is very much appreciated.

Kind regards
Niko Heeren

 

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