After two years of using flat icons for my rooms in my Fibaro HC2, I decided to try a different look. After searching for some nice icons, I found some round icons on http://www.flaticon.com/.
Go to http://www.flaticon.com/ and search for “car” for example:
Choose PNG and select as size 128:
Now click on Free download:
Upload the icon in your Home Center 2 as room icon: