Revit Schedules are extremely powerful tools even if you never plan on putting them on a sheet. It is an easy way to keep track of information in the model.
There are numerous ways to use the calculated total tool within Revit Schedules, but I will give you an example and you can then use this to fit your needs.
If I create a schedule like the one below and deselect Grand Totals and Itemize Every Instance this is what I get. You will notice that there isn't a value in the Area or Volume Columns for Wall Foundation and that is because there are multiple instances of this with differing values.
So if I want it to show the total for these I need to go to the Formatting tab and for Area and Volume select Calculated Totals as shown below.
The result will look like this