Enterprise calendars are used to define the operating hours for an organisation, as well as any exceptions such as statutory holidays or shutdowns for specific territories. They are used to standardise the working time for an organisation’s projects.

Enterprise calendars can be applied at 3 levels; Project, Resource and Task. Together the calendars are used to determine resource availability and the way that tasks are scheduled. I will try and use this blog post to explain how and when calendars can be applied at each level.

Before we get started it’s important to understand a fundamental difference when working with calendars in Project Online. When connected to Project Online, Project Managers are not able to create or edit calendars like they would if they were using a local version of Project. The enterprise calendars are managed centrally and are the responsibility of the Project Online administrators.

By default, Microsoft Project Online uses the Standard enterprise calendar as the base calendar for scheduling.

When configuring Project Online, the Standard calendar should observe the contracted hours for an organisation – the number of hours per day and per week, ideally with the same start time and end time per day. For the majority of organisations, this will look something like 8:00 AM to 5:00 PM, Mon-Fri with an hour for lunch. We will often see a slight variant to this, some organisations will operate a 7-hour day, and I’ve also worked with a client who operated a 7.4 hour day. However, the key is to ensure that common working hours are applied across all projects. There will of course be some exceptions, and these will be explored further in this post.

The Standard calendar should include any holidays; statutory as well as any other organisation-wide exceptions, for example, a Christmas closure period. This will ensure that project tasks are not scheduled for work during these times. It is advisable that the calendar is populated with holidays for the next 5-10 years. We usually assist our clients by also adding past holidays for 2-3 years prior to help accommodate in-flight projects that may need to be imported into the system.

Project Calendars

When working with Project Online, the Enterprise Standard Calendar is applied to all newly created projects by default. The Project Calendar is used to designate the default work schedule for all tasks in a project before resources are assigned.

Where existing projects are imported to Project Online via the import wizard, the system will prompt the user that Enterprise Calendars are required. The user will need to agree to change from the local Standard calendar applied to the enterprise Standard calendar to complete the import process.

Users can check which Project Calendar is applied by opening the schedule in Microsoft Project > going to the Project tab > selecting Project Information:Screenshot of 'Project Information' in a project calendar.

Some organisations may require multiple project calendars. For example, if some of the organisation’s employees work in another country, those workers will likely observe different holidays and so they will need a different enterprise calendar for scheduling project work.

When deploying Project Online across multiple territories, we do suggest that you have a standard working day and week regardless of where in the world projects are undertaken, this can avoid some weird results occurring where people who work in one territory work on projects deployed in a different territory. Whilst Project Online can accommodate many different enterprise calendars to model different territories, we would still recommend that they have common underpinnings in terms of hours per day/week and default start and end times, even if different calendar exceptions, i.e. holidays, are applied.

Resource Calendars

Each resource in the Enterprise Resource Pool in Project Online is also assigned a Base Calendar. Resource calendars are used to determine when resources are available to work on tasks to which they are assigned. Again, by default, the Base Calendar assigned will be the Standard Calendar, unless otherwise specified. You can therefore create additional enterprise calendars that can be applied to individuals or groups of resources.

For example, a group of resources only work part-time Monday-Wednesday and this needs to be reflected in the project schedules. Using a different resource calendar will allow you to apply different working patterns for a selection of resources, rather than for all resources in the organisation.

To amend the Resource Calendar, navigate to the Resource Centre in Project Online > select the checkbox next to the resource whose calendar you want to edit and choose Edit from the Resource ribbon.

Screenshot of 'Resource Calendar' within Resource Centre in Project Online

Under Base Calendar, select the calendar upon which the resource’s calendar will be based

Base Calendar options in Microsoft Project Online

Remember, as stated above, that the Project Calendar controls the schedule of each task before resources are assigned. Once resources are assigned to tasks, Project will be looking at the resource calendar to determine how the task is scheduled. If the resource calendar assigned to the individual differs to the Standard Project calendar, then the resource calendar will take precedence.

Again, although Project Online can accommodate many different enterprise calendars which can then be assigned to different resources, we recommend standardising working patterns as much as possible. Configuring too many enterprise calendars to manage can create an administrative overhead – always consider if it is worth the effort.

It’s worth mentioning that Resource Calendars can serve a different purpose. As well as defining a resource’s normal working pattern, resource calendars can also be used to define unique exceptions for individual resources, for example, to update non-working time such as planned leave. Although, be aware that this does have to be managed centrally by a Project Online administrator.

To add planned leave to the calendar of any resource, navigate to the Resource Centre in Project Online > select the checkbox next to the resource whose calendar you want to edit and this time choose Open from the Resource ribbon to open the resource profile in Microsoft Project

Screenshot of adding planned leave to the calendar of any resource in Project Online

From here, double-click the resource name > click the Change Working Time button in the Resource Information dialogue window.

Change working time in Microsoft Project Online Enterprise calendars.

Save the changes to the checked-out enterprise resource and then close the Enterprise Resource Pool file. When that resource is assigned to a task, the work will only be scheduled during their working time.  Again, as resource calendars are managed centrally, consider the administrative overhead on your system administrators before agreeing on this approach for managing holiday for each individual resource.

Task Calendars

When configuring Project Online for clients, we determine not only the Standard Calendar – which reflects normal operating hours for the organisation – but whether other Enterprise Calendars are required to allow some tasks to be scheduled outside of typical operating hours. Typical examples include a 24-hour calendar or a Weekend calendar.

Task Calendars are not used often but they are very powerful. By default, tasks do not have a task calendar assigned, instead, tasks will be scheduled as per the project calendar. However, Task calendars can be applied to a specific task as a great way to model “exceptions” to the standard working week. For example, if a task must happen over the weekend but the standard project calendar specifies weekends as non-working time, you can use a task calendar to enable the work to be scheduled just for that task over the weekend, while leaving the rest of the project using the standard project calendar.

To assign a different calendar to the Task, right-click (or double click) to open the Task Information dialogue window > go to the Advanced tab > Calendar > select from the base calendars available.

When a task calendar is associated with a task, it overrides the project calendar. However, to complicate matters, where a resource is also assigned, the task is scheduled based on the working times of both the task and the resource calendar. In some cases, it will, therefore, make sense to ignore the resource calendar.

To do this, check the Scheduling ignore resource calendar checkbox and this will ensure that only the task calendar is used for scheduling the task

Scheduling ignores resource calendars in Project Online

I hope the above provides a useful summary of the different types of calendars available when working with Project Online and how they are used. As we advise all our clients, the recommendation here is to keep things simple. Benefit from the functionality available but standardise as much as possible.

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By: Rachel Goodwin

Rachel Goodwin
Senior PPM Consultant, Wellingtone | An experienced PMO professional; P30 and PRINCE 2 certified, skilled at developing and implementing Project & Programme management methodologies, tools and best practices, with the ability to balance formal processes with pragmatism to drive delivery.

Published: 27 July 2020

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