Global Calendar Changes Affecting Project Calendars

Question

How do you prevent Global Calendar changes from changing the Project Calendars? When Project Calendars are created, they are copied from another calendar, say Global Calendar. Now, when the Global Calendar is updated or changed it changes my Project Calendar. How do you prevent this from occurring?

Answer 1

If the change to the Global Calendar is valid, it IS going to impact all local schedules. The Global Calendar is the basic Enterprise assumption. It is what contracts are written around.
If the projects are using a Global Calendar they are going to forecast the calendar, but a resource's calendar can allow performing a task anytime in the operational plan. That is the nature of high level settings and local or operational variants. Project execution is not nailed to the Global Calendar, Your original schedule forecasted from the Global structure and was accepted. If experience leads you to make change in the Global Calendar, that is reality. You will forecast the added knowledge gained from experience and set in the Global Calendar. If it creates Risk in the existing projects, deal with it locally. You record dynamic adjustments in the Actuals. You forecast local results from to-date actuals and local resource calendars. Management 'is' overcoming Global problems with local resources.
Leave the Global Calendar alone for operational exceptions. Remove exceptions from the Global Calendar. The Global Calendar is for planning. That Global Calendar is still the basic assumption, despite operational problems in your schedule. If the Global Calendar has a holiday, the projects it is assigned to forecast the holiday. Simplify your Global Calendars to match basic, high-level, factual assumptions.
Let your Resource Calendars forecast the detail of operations and overcome the Global Calendar. But actualize what happens no matter what any calendar says so calculation is up to date.
Calendars are strictly for calculation, for forecasting. You can always log progress on Christmas or during Ramadan, just as you logged no progress during the hurricane. But Joe Labor Unit will not forecast performing his task in NYCNY on even a regular Monday if his calendar has him training in Borneo. Cancel Joe's trip and change his calendar. He is available in NYCNY on the date you want now. His forecast changes, the project forecast changes. Primavera is perfectly dynamic. And the project will not forecast work on Christmas or during Ramadan if the Global Calendar says these are exceptions to your usual M-F 8-5 with an hour for lunch. Global Calendars are the sub-structure that we accept in building the initial, accepted Project Schedule and that provide the framework we analyze Risk mitigation around in operations.
"We're forecasting a late finish now due to the hurricane." "Schedule the workforce to work through the Christmas holidays." (adjust, adjust, adjust) "That brought completion in." The Global Calendar assumes no hurricanes and getting Christmas off. After the hurricane, the PM sets the operational guideline. The Scheduler adjusts the resource calendars to overcome the hurricane period's lost progress. As soon as the As-built has the adjustments, the schedule calculates and forecasts completion on time. The workforce is not scheduled to work Christmas in the Global Calendar. In their Resource calendars, now they are. The schedule forecasts work at Christmas. You mitigated the hurricane risk by overriding the Global Calendar with Resource Assignments. If you make those Resource Calendar Christmas adjustments in September when the hurricane hit, you will forecast project completion on time in the next report from P6. You pull completion back to the left after operational realities pushed it out to the right.
The original schedule is Art- planning, compromise and commitment. The ongoing fine-tuning and manipulation of As-built detail makes Art a Masterpiece by giving the heartbeat of the project and implementing the vision of its manager. Or not..