How is sDA calculated with Target DA

Hello friends
I had a specialized question, about the target sDA in the honeybee+ in certain period.
As We know , DA defined as the percentage of the occupied
hours of the year when a minimum illuminance threshold is met by the sole daylight.
and DA defined :
where ti is each occupied hour in a year; wfi is a weighting factor
depending on values of E Daylight and E limit that are,respectively,the
horizontal illuminance at a given point due to the sole daylight.
and the illuminance limit value.
Now when we decrease the Target DA to calculate the sDA, the sDA definitely increases. My question is, in the above formula, which parameter changes, that sDA increases?
and also, in the sDA formula(below), the DA is not in the denominator.
Can anyone clarify this for me? Basically, I want to know, scientifically, what happens when the DA decreases, the sDA increases. Does the total number of hours in a certain period decrease? Does the occupancy scheduale, which is between 8 and 18, decrease? For example, it is between 10 and 16.