Saw someone searching for this. Revit does not report Unconnected wall height so how can you put it in a schedule?
Algebra!
Area = Length*Height
Revit reports Area and Length. Solve for Height and:
Unconnected Wall Height = Area/Length
Create a Calculated Value Parameter and put in that formula to report unconnected height.
Architecture and Planning 
How do you get around the “Inconsistent Units” error? Is there something else needed here to get Revit to go from linear feet from square feet?
Never mind. The Type of Calculate Value needs to be “Length”. Thanks for posting this.
Glad you got it. Revit is ruthless with the units. One trick for me on a lot of things is to multiply by 1. That changes the type sometimes.
LOL… as long as you don’t mind inaccurate results! If the wall in question has door/window openings then your wall area figure is not that of the entire length of the wall. Autodesk needs to address this now – it’s ridiculous that we even have to have these conversations….. just make the damn paramter accessible!
This is just a simple example of how you could report the height. Yes, if you have cut-outs it will not work, but you know that – and should know that.
Revit scheduling is awful – but I don’t think they should fix it. What they need to do is provide the ability to export to a database without a plugin – as an export option – and the ability to spatially join data in Revit (maybe?).
If you use DB Link and export to a database, Unconnected Wall Height is reported. I do not think for any large project you should use Revit Schedules. Your data should be in a database. Revit should stick to modeling. Databases can manage the data. You should be using split models with your buildings anyway and not creating a million properties and entering data in Revit for everything.