# Simulation methods for practitioners

**URL:** <https://discourse.radiance-online.org/t/simulation-methods-for-practitioners/4589>\
**Category:** radiance-general\
**Created:** [July 18, 2018, 1:29am UTC](https://discourse.radiance-online.org/t/simulation-methods-for-practitioners/4589 "2018-07-18T01:29:16Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![German\_Molina](https://discourse.radiance-online.org/user_avatar/discourse.radiance-online.org/german_molina/32/492_2.png) [@German\_Molina](https://discourse.radiance-online.org/u/German_Molina)\
**Post date:** [July 18, 2018, 1:29am UTC](https://discourse.radiance-online.org/t/simulation-methods-for-practitioners/4589/1 "2018-07-18T01:29:16Z")

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Hello all,

I wanted to ask you, people, a question that has something to do with simulation methods, specifically focused on practitioners. Several of my (Groundhog) users are students and people who just want results.

**Context**

As a few of you may know, I am developing [EMP](https://github.com/GroundhogLighting/emp), which intends to become sort of a “higher level Radiance” that not only does simulation, but also pre and post-processing. The point is to allow a user to script on a higher level. For example, to say _“hey, emp, calculate the UDI on this workplane”_ instead of saying _“hey Radiance, grab this bunch of sensors (which I need to figure out), calculate the daylight matrices, multiply by a gendaymtx with this weather, etc.”_

**Question**

In the previous context, I want to use a method that is not too sensitive to user errors. For example, multi-phase methods have the problem caused by averaging partially shaded windows, which is why I tend to not use them.

In this regard, I was reading [THIS](https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/24542/1/p1280_final.pdf) article by E. Brembilla, and noticed that for global illumination calculations, the two-phase method (i.e. without sharp suns) works well. For direct solar illuminance, on the contrary, we need better methods.

I wanted to know what you think about the following methods for different metrics

**Proposition**

1. **UDI, DA, etc.** : 2-phase method with 145 Tregenza patches (seem to be fast and does not sacrifice too much accuracy for annual results)
2. **ASE** : Direct sunlight calculation (i.e. black world with MF6 source suns, like the 5-phase method)
3. **Photosensor (i.e. not workplane) calculation**: this intends to calculate sub-hourly illuminance. I want to use Standard Daylight Coefficients (i.e. Tregenza 2-phase method plus MF6 direct sharp suns)
4. **UDI, DA. etc. in models WITH BSDFs** : 4-component method (this is not yet supported)

Just wanted to know what you think about this. Would this combination be “good enough”/convenient for practitioners and students. I want to encourage the use of PROPER daylighting analysis on design stages, so accuracy is a concern.

I am planning to interpolate weather to 20-minute intervals, by the way. Is that enough?

Your opinion would be really appreciated! Thanks very much.