Hi Timo,Sorry for taking so long to answer your question. I needed help from our building experts. Marion Hiller from Transsolar helped me figure out how to verify these values.
The best way to know how the building is calculating the transmission of solar radiation is to back calculate the transmissivity, absorptivity and reflectivity of the window.
With an equation you can calculate the energy that is hitting the window: Q_total = I_total_on_facade * Area_window,where I_total_on_facade is the total radiation on the orientation corresponding to the window.
If you ask the additional outputs from the building QSOLTR (ntype 12) and QTSPAS (ntype 74), then you can calculate the values of
transmissivity = QSOLTR / Q_total absorptivity = (QTSPAS - QSOLTR)/Q_total reflectivity = ( Q_total - QTSPAS)/Q_totalThen, you can finally compare these values with the data in the window library corresponding to the specific glassing that you used.
I am attaching a modified version of the SunSpace example. It contains the results of the above calculations. Let's pick a time so we can compare: at hour 36, the calculated values are:
transmissivity = 0.34 absorptivity = 0.36reflectivity = 0.29 Incident_angle = 24°
If you go to TrnBuild, then to the window manager, and finally to the WinID library, you will see that the properties of the glazing used are: transmissivity_beam (Tsol)@30° = 0.413 ; transmissivity_hemispherical = 0.354 absorptivity_beam@30° = Abs1 + Abs2 = 0.123+0.201 = 0.321; absorptivity_hemispherical = 0.132 + 0.191 = 0.323 (There are two values of absorptivity, one for each of the surfaces of the glazing).
reflectivity_beam(Rfsol)@30° = 0.262; reflectivity_hemispherical = 0.314The overall results that you get with the above equations are weighted averages for the beam and solar radiation.
In addition, you can also ask for ntype903, which is a balance of solar radiation on a window. I hope this helps. Please do not hesitate to contact me again if you have additional questions.
Best regards, Diego Timo Sengewald wrote:
Diego, thanks for your answer. I already tried QSOLTR but it seems the amount delivered is too low and I tried QTSPAS (NType 74) which delivers more plausible values (compared with the incidence radiation on the outside wall). The documentation says about QSOLTR: NTYPE 12: QSOLTR total shortwave solar radiation transmitted through external windows of zone (but not kept 100 % in zone) [kJ/hr] Isn't the shortwave radiation the visible part of the solar radiation? Thatwould explain the pretty low energy rate.Best regards, Timo ________________________________________________ Timo Sengewald BLS Energieplan GmbH Elsenstraße 106 D-12435 Berlin Tel.: +49 30 53 32 81-0 Fax: +49 30 53 32 81-40 www.bls-energieplan.de -----Ursprüngliche Nachricht----- Von: trnsys-users-bounces@engr.wisc.edu [mailto:trnsys-users-bounces@engr.wisc.edu] Im Auftrag von Diego A. Arias Gesendet: Freitag, 17. März 2006 23:51 An: Timo Sengewald Cc: trnsys-users@engr.wisc.edu; ausgang@bls-energieplan.de Betreff: Re: [TRNSYS-users] Type 56, components of heat gains Dear Timo,Ntype12 (QSOLTR) gives you the total shortwave solar radiation transmitted through external windows for a given zone.Best regards, Diego Timo Sengewald wrote:Hello! Currently I try to estimate the single components the total thermalgain of a room is composed of (observing a single day). Could somebody tell me which NTYPES of type 56 deliver the solar radiation transmitted through the windows?Thanks for your help! Best regards, Timo ________________________________________________ Timo Sengewald BLS Energieplan GmbH Elsenstraße 106 D-12435 Berlin Tel.: +49 30 53 32 81-0 Fax: +49 30 53 32 81-40 www.bls-energieplan.de ----------------------------------------------------------------------- - _______________________________________________ TRNSYS-users mailing listTRNSYS-users@engr.wisc.edu https://www.cae.wisc.edu/mailman/listinfo/trnsys-users
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