Daysim parameters list of illuminance / Irradiance sensor points

Dear all,

I am having some problems with the daysim parameters object. I want to run an annual daylight simulation using the daylight coefficient method and request both illuminance as well as irradiance in the interior as an output. If I enter a single value requesting either all test points to sense Irradiance or Illuminance everything works fine. However when I feed the component a list of ‘sensor file unit’ data it appears to only select the first entry of the list and write that value into the .hea file for all points.
I have tried grafting the list, feeding the list of numbers as a list of strings and as a single string. None of these worked. I could off course manually change the values in the .hea file however we want to automate this process and run a batch of simulations so I am not too keen on manually editing.

Kind regards,


What I assign in honeybee:

What get’s written into the .hea file:

(the second to the eigth values here should say 0)

1 Like (520.2 KB)

P.S.: I forgot to attach a grasshopper definition illustrating the problem

Hi @SamueldeVries , are you sure you are also calculating irradiance? If I remember correctly, Daysim does not allow you to calculate irradiance separately.


You can’t get both of them in the same run because one will overwrite the other one. However you can set them in the same definition and save them in two different folders.

Keep in mind that when you calculate irradiance you have to use SHGC of the glass and when you calculate illuminance you want to input TVis. Unless SHGC and TVis of the glass are the same or you’re working on and outdoor case you need two models for these two studies.

Hi Sarith and Mostapha,

Thank you for you replies.
@mostapha: because we couldn’t get the irradiance and Illuminance to work we ended up implementing it like you suggested.

All the better because, as you point out, the results wouldn’t have made much sense as the transmissivity that is used by Radiance/daysim has to either refer to the full solar spectrum or only the visual one.
To be honest: a student asked me the question of how to implement this and in retrospect I think I haven’t given the overall methodology enough thought before posting the question. Thanks pointing this out.

As for what to input in terms of transmittance: I would think that in our case the most correct thing to do would be to use the solar transmittance (LBNL window gives this) rather than the SHGC as the latter would also contain radiant heat transfer from the inner pane (the student is interested in transmitted solar irradiance).

Kind regards,