Re: [TRNSYS-users] direct and diffuse solar radiation through glazing

[Marion Hiller <Hiller@Transsolar.com>]

Dear Wirich Freppel,

 

I wonder if this question is still open.

For an external window the incident total radiation has definitely to be less than the transmitted one and I’m sure that this is the case.

 

According to the results, at day time, so when there is solar radiation, Total tilted surface is below the others.

• At which output are you looking for “Total tilted surface” ? Note: The comparison “Total tilted surface” to “QSOLTR” makes sense if the zone has on external window only!!! (QSOLTR is for all windows of a zone!)
• If you have one window only you even can calculate back from QSOLTR the split between  direct and diffuse radiation by an equation because the solar diffuse transmittance is time independent. This solar diffuse transmittance is given by the glazing definition.

 

I have the feeling that an output QSOLTR as a surface output might be helpful in the futur.

 

Kind regards,

 

Marion

 

 

-----------------------------------------------------------------------------------------------------------------------------------------------------------

Dipl.-Ing. Marion Hiller 
TRANSSOLAR Energietechnik GmbH 
Stuttgart - Munich - New York - Paris  

t: +49.711.67976.0   f: +49.711.67976.11

www.transsolar.com/   

KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden 
Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart

Amtsgericht Stuttgart - HRB 23347 / Steuernummer: 99073/00911 / USt-IdNr.: DE 152272639
Geschäftsführer: Matthias Schuler, Thomas Auer, Stefan Holst, Dieter Schnelle 

 

 

Von: TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org> Im Auftrag von Freppel, Wirich via TRNSYS-users
Gesendet: Freitag, 7. Februar 2020 10:09
An: TRNSYS USERS (trnsys-users@lists.onebuilding.org) <trnsys-users@lists.onebuilding.org>
Cc: Freppel, Wirich <Wirich.Freppel@saint-gobain.com>
Betreff: [TRNSYS-users] direct and diffuse solar radiation through glazing

 

Dear TRNsys users,

 

I apologize in advance as this subject was already discussed one year ago, but I think some more explanation could help me to go further in my study. (http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/2018-November/030610.html)

 

I’m trying to calculate the Effective Radiant Field of an occupant, based on TRNsys outputs. To complete the calculation, I need the total diffuse solar radiation entering the airnode through glazing, as well as the total direct radiation. Not being sure of what output I should choose, I compared :

• Total tilted surface radiation (which I assumed to be the total direct and diffuse solar radiation arriving on the window)
• QSOLTR (which I assumed to be the total shortwave solar radiation transmitted through the window to the airnode)
• QTABSI (which I assumed to be the total radiation transmitted to the airnode)
• QTSGL (which I assumed to be the total solar radiation passing from outside surface of the window to the airnode)

 

According to the results, at day time, so when there is solar radiation, Total tilted surface is below the others. So it means, according to what I see, that solar radiation is bigger after going through the window. After those results, it’s difficult to say I understood well what I am doing…

Could you help me to understand those outputs and advise me on the output to choose for “total diffuse solar radiation entering the airnode” and “total direct solar radiation entering the airnode”?

Marion mentioned to use “QSOLTR-QTSOUT”. That would be ok for me, but why is QSOLTR bigger than total tilted surface radiation?

 

Again, I’m really sorry for digging out that topic again but I do think my interpretation is very bad at the moment.

Thank you in advance for your help.

 

Wirich FREPPEL
Development engineer, PhD

COSMOS - Buildings Energy Performance & Daylighting Group

Cell: +33 637 053 174

Saint-Gobain Research Compiègne