sDA calculation

Federico587 · December 20, 2017, 12:15pm

Hi,

I think that there could be an error in the ouput from the sDA component.
The sDA calculated from the DA results gives me a different result than the one from the sDA component.

Am I doing the right calculations?

Best regards,

Federico

saram · December 21, 2017, 3:05am

Hi, I am having the same issue. It seems sDA is too low (almost 2 or 3%) for north oriented windows with descent sizes. One thing I notice is that DA is insensitive toward occupancy schedule.

I used the same approach as you illustrated in the image to calculate sDA but when I disconnect the schedule, the calculated sDA did not change! So my interpretation was that probably DA is insensitive toward the schedule. But UDI got updated.

Federico587 · December 21, 2017, 5:42am

Hi @saram,

Sometime you need to disable and enable again the component, but I do not think that this is the case.
I checked the DA and sDA output for the same simulation but with different schedules, and I can see the changes.
Maybe the problem is with the schedule component. Check the values with ladybug 3D chart component.

mostapha · December 24, 2017, 5:51pm

@Federico587,

Thank you for double checking the results and reporting this. This looks like a bug. I checked the source code and it seems I have calculated the % of time instead of the % of area for sDA.

github.com

ladybug-tools/honeybee/blob/0fc2acebbb203f03960ba7856100c102328cb5c6/honeybee/radiance/analysisgrid.py#L503-L582


def spatial_daylight_autonomy(self, da_threshhold=None, blinds_state_ids=None,
                              occ_schedule=None, target_area=None):
    """Calculate Spatial Daylight Autonomy (sDA).


    Args:
        target_area: Minimum target area percentage for this grid (default: 50)
    """
    results_loaded = True
    if not self.has_values and not self.result_files[0]:
        raise ValueError('No values are assigned to this analysis grid.')
    elif not self.has_values:
        # results are not loaded but are available
        assert len(self.result_files[0]) == 1, \
            ValueError(
                'Annual recipe can currently only handle '
                'a single merged result file.'
        )
        results_loaded = False
        print('Loading the results from result files.')

This file has been truncated. show original

This is a major bug and I’ll try to fix it as soon as I can. We should have a new release soon to address this issue.

Federico587 · December 26, 2017, 1:26am

Hi @mostapha,

it is a pleasure that I can contribute just a little to this fantastic tool!
If I may, since we are talking about bugs, do you mind have a look to the schedule component?
As it is discussed her with @saram, it seems like the this component behavior is a little strange.

It is fantastic that you always improve this tool. Thanks.
Best regards,

Federico

mostapha · February 7, 2018, 4:21pm

4 posts were split to a new topic: Blinds/shades operation in sDA calculation

mostapha · February 7, 2018, 4:03pm

The original bug in sDA calculation is now fixed. I can’t recreate the issues with the schedule myself. @saram has provided me an example which will hopefully recreates the error. I will discuss the blind state discussion in a separate reply.

mostapha · February 8, 2018, 1:15am

@saram, I think in you case the DA values didn’t go lower than 50 so it didn’t change the sDA. From the cases that I have tested the values are changing after changing the schedule.

saram · February 8, 2018, 1:54am

Thanks for fixing it. Please let us know when you are applying the shading algorithm to LEED sDA calculation.

mostapha · February 8, 2018, 12:46pm

Hi @saram, You should follow this topic for blinds operation implementation and share your thoughts: Blinds/shades operation in sDA calculation