Report: Availability report based on Time Periods (not service times)

We would like to create some availability reports for example my business intelligence groups. The thing is that I only can honor downtimes, notification periods and service times.

In Time Periods we’ve declared our for example Working hours which are SLA relevant. And I want to get a report based on the availability on those Working hours for the BI aggregation.

From technical view it looks like a similar sql select to filter events which are not in a specific timeframe like the service periods…