Hi,
EnergyPlus uses angular properties for beam transmitted solar to correct the solar transmission coefficient the user inputs. Does that apply also to the interior window that does a beam-to-diffuse transmission? It should but I can't see that in my outputs...
thanks for the help!
Aymeric
--- In
EnergyPlus_Support@xxxxxxxxxxxxxxx, ppeixeiro@... wrote:
>
> Your interior window is defined two times: once in each zone they
> seperate. It might be the case that you're reporting "Beam Solar
> transmitted through interior window" for the inteiror window on the
> surface of the DSF zone, and it should be the window that is located the
> surface of the main zone.
>
>
> > Pedro,
> >
>
> In regards with the transmission of solar energy through the double skin,
> > I have a question:
> >
> > In the results, we can see that the output variables at the building
> > central zone level (the zone supposedly protected by the DS system)are
> > generated, say you have about 20kW of Zone beam solar from interior
> > windows and 40kW of Zone diffuse solar from interior windows.
> > It is weird that I have a 0 value for the interior window level ouput
> > "Beam Solar transmitted through interior window" I don't quite understand
> > that...
> > Because of that I am not sure anymore how E+ handles the solar in and out
> > the zone and the cavity.
> > I am not sure if the big difference I was talking about in my first
> > message was not due to the fact that only the diffuse part is well treated
> > here...What do you
think?
> > Because the impact of the cavity airflow is clearly on the glazing net
> > gains which makes sense since it cools down the structure that was partly
> > charged with solar heat, hence one can say it takes away part of the sun
> > heat (although I still think it is small).
> >
> > Aymeric
> >
> > --- In
EnergyPlus_Support@xxxxxxxxxxxxxxx, Pedro Peixeiro <ppeixeiro@>
> > wrote:
> >>
> >> Hi Aymeric
> >>
> >> SHGC is the amount of solar radiation that enters a room both directly
> >> transmitted through the facade and the fraction of radiation that its
> >> absorbed by the facade and then transmitted into the room
by both
> >> convection and radiation heat transfer. In the pressence of a DSF, there
> >> is a certain amount of heat transfer occurring inside the cavity (heat
> >> removed by the air flow). This amount is not stationary, because it
> >> depends on wind incidence, wind velocity, temperature difference between
> >> cavity air and outside air, and surface temperature of the panes.
> >> Because of this un-steady state heat flow, its not possible to establish
> >> a convectional SHGC value for a DSF. Also, in reality, the heat flow
> >> also varies with the height of cavity (temperature inside the cavity
> >> increases with height) and so will heat transfer through the inside
> >> pane. So it basically means we would get a difference SHGC value in
> >> function of height, which complicates even more a definition of a
single
> >> SHGC value for a facade.
> >>
> >> Pedro
> >>
> >> On 01-04-2011 11:43, aymericnovel wrote:
> >> >
> >> > Dear all,
> >> >
> >> > I am studying a double skin facade design. I want to compare with a
> >> > design using a simple skin with windows that have a SHGC of 0.25
> >> > because it is the assembly SHGC I have to reach according to the local
> >> > chinese standard. See the architect have asked me to justify the cost
> >> > of using the external skin...good question when you think about it!
> >> >
> >> > So I have chosen inner skin and outer skin glazings so that it is
> >> > equivalent first with a simple approximation of SHGCin x SHGCout =
> >> > 0.25 . I know it is too simple but still it should not
be too
> >> > different in the zone inside the building.
> >> >
> >> > I am having trouble understanding the following fact:
> >> >
> >> > Having a combined SHGC of the inner and outer skin very close to the
> >> > simple skin I try to compare with, I do not obtain at all the same
> >> > amount of sun in the zone inside the building. Why? Normally the sum
> >> > of the direct and diffuse solar transmitted through the internal
> >> > windows should be close to the one through the external window in the
> >> > case of the simple skin no?
> >> >
> >> > I have the feeling I am totally missing something basic here but it's
> >> > late and I don't see it.
> >> >
> >> > Your help is more than appreciated!
> >> >
>
>> > Thanks
> >> > Aymeric
> >> >
> >> >
> >>
> >
> >
> >
>