[EnergyPlus_Support] Re: Surface outside tempearture vs solar radiation.

["yli006" <yli006@xxxxxxxxxxx>]

I have seen  E+ simulation result on roof temperature in Kucing, East
Malaysia.

The  measured and the simulated result are quite close.  For example, 
55°C simulated and 66°C  (about 150°F) measured.

The weather station is about 5 km away from the location where the roof
temperature was measured.  The measured outdoor air temperature was
about 30°C, and is a degree or two from the temperature at the
weather station.  The acture weather station data taken on the same day
was used for the simulation.  The calculation was of course not done on
the same day as the measurement.

My roof surface is sloping and trapesoidal (still  only4 vertices).  The
roof material is sheet metal, with insulation inside.

I am not sure what was the oritinal concern of the writer.  The shape of
the roof should not be a problem, if the points are entered correctly. 
Within an hour duration, the measured temperature can vary between the
out door air temperature and the maximum observed temperature.

If the simulation is reporting the average temperature over an hourly
period, it would be lower than the peak value.

The simulated roof surface temparature can  vary with  roof material
entered in the IDF file,  ventilation condition, and weather file time
and location.

The measured temperature can  vary with the way the thermal couple or
thermometer  is attached to the roof.

The experiment is still going on in Kuching.  I am only an oberver from
Canada, monitoring the progress of the project.

Dr. Li.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Linda Lawrie" <linda@...>
wrote:
>
> I have not been able to find any reason (yet) for your problems though
> I believe I verified it. Our example file with > 4 sides, does not
> exhibit any problems.
>
> I would suggest you try an equivalent area surface for that roof and
> see if that helps.
>
> Linda
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jose Benitez" joseb@
> wrote:
> >
> > I have done these types of simulations, generally I have problems
with
> > surfaces with more than 6 vertices's. The problem lies with the
> > calculation of direct solar radiation incident on these surfaces.
> > Further description of the problem can be found on post 11936. For a
> > tropical climate I have found outdoor temps to reach 150F on a 6"
> > concrete roof, a simple way to check is to calculate the sol-air
temp.
> > I am still waiting on a reply from Linda on this problem.
> >
>




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