[Radiance-daysim] Calculation of the solar irradiation with Daysim

[Christoph Reinhart]

- What solar irradiance spectrum is measured if I use irradiance sensors instead of illuminance sensors?
The Daysim program ds_illum has a luminous efficacy model according ot Perez built in that converts irradiance into illuminances if you choose the latter type of output. Otherwise, DAYSIM just uses the direct and diffuse irradiances for an epw weather file. Typically those should have been measured with a pyranometer, i.e. they should correspond ot the full visible and IR spectrum.

- Could Daysim take into account the SHGC of different window glazing?
If you use the irradiance output the window transmittance should indeed correspond to the window’s SHGC.

- Is it possible that the glazing system was opaque to the long-wave radiation?
I am unsure what you mean here. DAYSIM/RADIANCE use simplified RGB (3 channel) or often effectively 1 channel simulations and do nto support a full spectral analysis. I believe that Mehlika Inanici is working on a spectral version of RADIANCE.

Best,

Christoph


From: Abigail Chi [mailto:abigailchi at gmail.com]
Sent: Wednesday, August 10, 2016 9:32 AM
To: radiance-daysim at radiance-online.org
Subject: [Radiance-daysim] Calculation of the solar irradiation with Daysim

Dear all

I am working on different daylight simulations with Daysim 3.0. My interest is to calculate the solar irradiation but I have some queries:
- What solar irradiance spectrum is measured if I use irradiance sensors instead of illuminance sensors?
- Could Daysim take into account the SHGC of different window glazing?
- Is it possible that the glazing system was opaque to the long-wave radiation?

Thanks in advance

Abigail

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