[esp-r] Re: Problems with TMC & mlc

[Jon Hand (clcv10)]

A recent question:

::I have created a multi-layer construction by applying a glazing to  
the external face of a wall mass. When I run the ::simulation, the  
following message appeared:

::Warning: in../zones/GF-R1.tmc: 0 OKALUX-T the glazing element value  
<0> < normal minimum 1!
::Mismatched TMC & mlc layers:

The number of layers in the construction should have the same number of
layers as the optical properties.  If you added a layer of glass to  
an existing
construction to make a new one you are probably going to have to create
a new optical property set with the same number of layers.

Assuming that at least some of the layers in this construction are  
actually
opaque you are going to have a difficult time using any of the normal
tools (WIS Window5.2) typically used to create optical properties  
because
they do not deal well with the concept of glazing systems which have
totally opaque layers - they tend to crash.

It then becomes interesting to speculate as to what happens in
a construction which has an outer glass layer?  Certainly any
solar radiation that gets into the room will interact with this entity
which is sort of opaque and sort of transparent.

In other project where designs such as transparent insulation have
been modelled a common approach was to treat the air space behind
the glass as a zone (albiet a rather thin one) so that the construction
on one side was the mass of the buidling and the construction on the
other side was a glazing system. Of course a zone can be ventilated
and has full radiant and convective exchange which might be useful
in the case of glazing added to an wall construction.

If you are determined to have this as one construction then in WIS
or Window5.2 you should pretend that the wall behind the glass
is slightly transparent. Usually a few percent will allow calculations
to proceed.

-ESRU
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