[EnergyPlus_Support] Precise surfaces modelling

["serge.gosset" <e-sim@xxxxxxxxxx>]

Hi everybody,

I am trying to figure the best way to model old building surfaces
(meaning an impressive thickness, especially when we add a comfortable
insulation layer).  I have been browsing the documentation and the
Yahoo group, but some issues are still unclear to me.

Let's summarize:
1.- wall thickness is used only for heat transfer and thermal capacitance
2.- wall surfaces are used only to determine the zone air volume as
well as the lighting masks and radiation part of the heat problem.

Hence a few questions arise:
a) What happens with narrow windows in thick walls: there is an
obvious solar mask caused by the wall that is not modelled with
zero-thickness surfaces?  Should we model only the internal surface
and add non-thermal masks on the outside to simulate the window
opening sides ?

b) Or should we model the outside surface only ?  Have you any idea on
which is the more thermally accurate ?  Masks should be massless
inside the thermal zone in this case, or should we put them in a
non-thermal zone also ?

c) For inside walls between zones, both surfaces are hit by radiative
power.  To have a precise modelling of this, we should use both
surfaces in their exact position, but we can model only a
zero-thickness surface in E+.  Right ?  Or can we define two different
surfaces separated by 5o cm and tell E+ that they are both sides of
the same heat transfer surface.  Can we do this or something similar
and, if yes, how ?  Can it be automated some way (like in Ecotect, for
example, in which a tolerance is given below which surfaces are
considered being both sides of the same wall/partition) ?

Any suggestion or best practice here ?  This would be an interesting
topic for many users, I guess ...

Thanks for your reply & best regards to all

Serge


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