If you want to create a filled region in a way that Revit automatically collects room boundaries and you just want to select a color than this script is perfect for you.
You can use existing filled region color or you can choose in the script user interface new color for the filled region.
The script will let you choose if you want to perform coloring for the cooling or for heating, but that’s just created in order to present the script. With a little effort, you can customize this script to meet your needs.
Please make sure that before you start using this script that you back up your existing project model.
Also, if you want to download this (and all other scripts) with my sample files please visit the Shop page.
The script uses the following Dynamo packages: Data-Shapes, 2019.2.42 Genius Loci, 2020.8.20