Hello Uta,
Thanks for your entries so far! As said before, they all look very nice.
Entries #12 and #15 look the closest to our idea of how our logo should look like. They're both subtle and look professional. The font should be in the front and the house - not even necessary, can be schematic as well - doesn't even have to be fully recognizable in the logo.
Your efforts are much aprreciated!