Hey @JonathanASP ,
This is a really good question and I would be interested in hearing the thoughts of @mostapha , @mikkel and @sarith on it. In the meantime, I can explain what currently happens in the “Annual Daylight” and “Annual Irradiance” recipes.
In order to get the simulation to run as fast as possible, the annual daylight and annual irradiance recipes currently only run the calculation for hours when the sun is above the horizon. We figure out these hours by means of the honeybee_radiance.sunpath module, which is essentially using the ladybug.sunpath module under the hood.
The ladybug Sunpath is certainly capable of computing how far below the horizon the sun is. So it would not be very difficult for us to just change these sun-up hours to include hours where the sun is 5 degrees below the horizon, for example. However, I don’t know enough about Radiance to say for sure that the gendaymtx command that we use under the hood to account for the diffuse sky irradiance is still going to produce non-zero values even when the sun is below the horizon. Nor do I have a sense about whether these types of dawn/twilight conditions produce anything close to a meaningful level of light, though I feel intuitively that they do as I sit in civil twilight as I write this.
Perhaps with some input from the people above, we can decide whether a change the the annual recipes is merited for this case.
In the meantime, the Point-in-Time workflows are probably the right way to go since, as you say, the CIE model is robust enough to model dawn/twilight conditions.