Global Parameters are often overlooked in Revit but can be extremely useful. So what are Global Parameters?

Lets use an example. In the sample Revit project “RAC_basic_sample_project.rvt”, we have a number of windows on Level 1 which we are going to control the Sill heights at a project level.

Using a Global Parameter on the Manage tab we will create a new parameter.

Clicking the New Global Parameter button I will use the following settings:

Name: Sill Height
Discipline: Common
Type of Parameter: Length
Group Parameter Under: Dimensions

Clicking OK will create the new Global Parameter. Currently it has a value of 0.0 but I am going to change this to 100.

Selecting one of the windows on Level 1, I will click the Associate Global Parameter button next to Sill Height in the Properties window.

From the list select Sill Height and click OK, the Sill Height property will now grey out as it is now controlled globally.

You will also notice that the window has updated to have a Sill Height of 100 just as we set in the Global Parameter.

I can apply this Global Parameter to all windows which need to match Sill Height.
Changing the Global Parameter again to 200 will now also update all the windows instantly to a Sill Height of 200.