Re: [EnergyPlus_Support] inside surfaces

["Michael J. Witte" <mjwitte@xxxxxxxx>]

See answers below.

On 28 Feb 2003, at 16:45, santuta santuta@xxxxxxxxx wrote:

> 
> Hello again,
> 
> I am trying to simulate a generic office in the middle of a building.
> For this I used "OtherZoneSurface" for all the interior surfaces
> (including roof and floor) and used each interior surface as exterior
> environment for itself, since all the building would be conditioned at
> approximately the same temperature. Doing this I got very close inside
> and outside temperatures for these surfaces. However I have problems
> understanding a couple of results:
> 
> 1-Although the I-O temperatures are quite close, they`re not equal as
> I would expect. Is this normal?

A slight difference is normal, because the outside surface heat 
balance is done once at the beginning of the time step and then the 
inside heat balance iterates.

> 
> 2-The conduction through these surfaces (which I would like to be
> zero) is quite high compared to exterior surfaces. I am using "Opaque
> Surface Inside Face Conduction", and the relation between deltaT, U-
> value and conduction seems inconsistent. For instance, a typical
> temperature difference for interior surface is between .3C and 1.3C,
> for exterior surfaces is up to 12C. However, the conduction remains in
> the same order of magnitude, even if I choose a higher U-value for the
> exterior wall. How can this be possible?

"Opaque Surface Inside Face Conduction" is the heat flow into/out of 
the interior (thermal mass) of the surface.  It does not represent 
conduction across the surface.

I think we need to rename this output variable, because it causes 
much confusion.  Suggestions anyone?

> 
> 3-I am aware that a solution would be to define these surfaces as
> internal mass, and not as heat transfer, but I am concerned with the
> effects on radiation and daylighting results, that if I omit floor and
> roof might change. Is this correct?

Yes, if you are doing detailed daylighting or full interior solar 
distribution.

Mike


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