topic Re: daylight factor analysis 2017 in Lighting & Solar Analysis Forum

daylight factor analysis 2017

Anonymous — Tue, 30 Aug 2016 14:54:06 GMT

Hi, I am running an Autodesk Building Design Suite Premium 2017 commercial license and testing Insight360 as more dynamic alternative to Velux in an architectural firm. The first goal is to generate Daylight Factor Diagrams with Lighting Analysis in the cloud, but there are some issues that I could neither fix myself nor find in the other threads (resulting in odd outputs from the program, ranging from degrees of lighting in totally open spaces and totally closed rooms with spots of light to really high or low lighting values, usually combined):

- When defining glazing properties for illuminance, does the thickness and number of panes of the table on Autodesk help refer to the Revit-modelled elements or the desired windows designed? If it is the former, would that mean that all window elements should be remodelled for daylight calculation purposes? If the glass panes are extrusions, would that count as a surface or as two (as in Velux)?

- I remain confused about which are the daylight conditions taken into account. Are the ones that I configure in the Study Settings / Environmental Settings and others, or the ones I configure through the Rendering Settings of the Camera 3dView of the Lighting Analysis Model View generated in Revit? Does it depend on the Advanced Settings configuration? How? I want to set an equinox cloudy condition for the Daylight Factor analysis, but I am not sure of achieving it.

- All outputs I saw come on Lux (or footcandles). How can I make it correspond with aprox. equivalent Daylight Factor Units? I read some posts on the topic online, but I'm not sure if my final nonsensical results come from previous mistakes or also get distorted at this step. I'd like to get an insight anyway on the correspondence of units, so it gets a bit more controlled.

I hope this post could help others as well. Thanks in advance.

Re: daylight factor analysis 2017

stephanie.egger — Thu, 01 Sep 2016 00:36:45 GMT

Hi @Anonymous,

Here are some responses to your questions. Let me know if they make sense. Overall there are 2 ways you can do a Daylight Factor analysis from Revit:

1. Use the Insight 360 plugin and access the Lighting command. Select Custom analysis type, and set the Sky Model to Daylight Factor Sky. With this workflow, you results will appear in your Revit model. The analysis times and solar settings are not used when using this sky condition, so you can ignore those settings. For DF simulation the sky is automatically set for a 0-100 lux illuminance on horizontal surfaces in full sun.

2. From the View menu, select Render in Cloud. For Output Type, select Illuminance, and under the Sky Model tab select Daylight Factor Sky. For this workflow, your results will NOT appear in Revit, you will have to access them in the A360 Gallery.

The thickness and number of panes in that table refers to what is modeled in Revit. Not actual IGU specs. Most default families have the glass geometry modeled at 1" thick. This thread has a worksheet that will help you figure out the RGB values to specify. The number of surfaces and panes is taken into account in this worksheet.

Hopefully my explanation above clarifies the different workflows. Basically the settings are separate between the workflows, but things like your surface reflectivity and Tvis values assigned to glass are picked up by both. Since by definition Daylight Factor is represented in an overcast sky condition, you don't have to specify it--we take care if it for you.

I would suggest you make a custom analysis style for visualizing Daylight Factor results. See this thread for further explanation, but essentially, you can create a custom legend that will make sense for DF results. In this workflow, lux are the stand-in value for DF, so if you run the simulation with lux, then apply a legend like the one at the link, you should be in good shape.

Re: daylight factor analysis 2017

Anonymous — Fri, 02 Sep 2016 10:30:06 GMT

Hi Stephanie,

Thank you for your reply. It makes sense and helps, but I still remain halfway.

It was clarifying the separation between what belongs to each way to do Daylight Factor analysis. I will stick to the Insight method since cloud rendering seems be limited to the 3d views.

I may say though that I was doing everything you say (but for a (not crazy) different transmittance number in the glass surfaces) when getting the awkward outputs. First of all, I cannot understand how can I have uneven distributions of lighting outdoors:

Could it be for a very low general level of lighting (I do not why)? I guess so because the plan daylight factor analysis shows as if the windows were almost opaque (and they are not). Let alone the fact closed rooms which should not have any lighting whatsoever show the highest levels of lighting.

I don't really get either how are the light conditions. You say at the beginning of the reply that the program calculates Daylight Factor for full sun conditions, while later on you say that the default is overcast. I understand that I don't have access to manually set weather conditions, but would like to know which are the ones the program uses.

On the other hand, I tried before too to make a custom analysis style for visualizing Daylight Factor results following the thread you send me. The problem is that it looks like the previous picture and not as it shoud.

Thanks for the help.

Rodrigo

Re: daylight factor analysis 2017

stephanie.egger — Tue, 06 Sep 2016 23:36:45 GMT

Hi Rodrigo,

Can you check your Rendering Settings for the _Lighting Analysis 3D view for me? Based on the lack of illuminance levels outdoors, and the high illuminance levels indoor, I'm wondering if Revit is only considering electric lights, and not sunlight.

Also, make sure that your advanced settings Override "Lighting > Scheme" is checked.

It also sounds like while your glazing is appearing as transparent, it actually isn't. Make sure you are following these guidelines when specifying glazing materials.

http://help.autodesk.com/view/BUILDING_PERFORMANCE_ANALYSIS/ENU/?guid=GUID-5734F60C-2D58-4D61-B0E4-0FD336853A3D

-Stephanie

Re: daylight factor analysis 2017

Anonymous — Wed, 05 Oct 2016 10:46:44 GMT

Hi Steffanie,

The problem was not the glazing transparency. That I had adjusted before according to the same link you sent in your previous mail. The problem (or at least one of them) was that the general level of lighting was so low that few light was passing through the glass into the rooms.

Therefore I played around with the lighting settings. I found out that with these display options (full ambient light-no sun, which are indeed the ones that make more sense to the daylight factor calculation, as we do them in Velux):

These environmental settings:

And keeping unchecked the overriding of the lighting scheme and background style in the advanced options:

And not with any other combination I tried, I got a sort of reasonable output like this:

However it is still odd, it showed me that the program can actually do the calculation, which is even sadder. I mean, we are looking for a certain software, willing to use it and up to pay for that. It happens to be that apparently we are already running that software in our computers. However its interface and tutorial are so uneasy that neither I can rely on it enough to show its outputs to our clients nor I can explain a clear step-by-step working process to my colleagues.

I know that we are not the only architects facing this discouraging situation with this product. Therefore I am sure we are not be the only ones wishing to read or attend to a clear explanation on how to use Insight for daylight calculation. I hope someone could do it for the good of both you and us. Thanks for the help,

Rodrigo

Re: daylight factor analysis 2017

stephanie.egger — Tue, 03 Jan 2017 20:47:27 GMT

Hi Rodrigo,

I think one of the problems you were experiencing was because you were using the same date and time (March 19 @12). If you set different times, then the results will likely generate in a way that makes more sense.

The reason for my follow up now is that we released a new version of the plugin available for Revit 2017. In addition to some new features (daylight autonomy and solar access) it has some fixes that I think will help with the inconsistencies you were seeing before.

You can download it from here, and I’ve included some of the resources as well. Let me know if anything is unclear.

Best & Happy New Year,

Stephanie

Re: daylight factor analysis 2017

Anonymous — Fri, 10 Mar 2017 08:35:34 GMT

Hello,

We have REvit 2017 with 2017 plugin.

We need to run Daylight factor analysis. But we do not not have option to set analysis to custom, we do not know or cannot see option to see result in DF- percentage- We are only getting results for LEED not DF/Breeam. We do not know how many lux does CIE overcast Sky or Daylight factor Sky has.

I would be greatful for help/information.

Kind Regards

Wiktor
Kuryłowicz&Associates, Warsaw, Poland

Re: daylight factor analysis 2017

stephanie.egger — Wed, 19 Apr 2017 22:34:46 GMT

The CIE Overcast Sky produces results in lux or footcandles, while Daylight Factor sky provides results as a percentage of natural light falling on surfaces compared to that which would have fallen on a completely unobstructed horizontal surface under same sky conditions. The location or time of day does not matter if you are using a Daylight Factor Sky. Results will be expressed as a percentage. See this thread about setting up analysis results for DF Sky. https://forums.autodesk.com/t5/lighting-solar-analysis-forum/daylight-factor-analysis-using-revit-2016/td-p/6013565

-Stephanie