I don't believe many folks will consider bat avoidance unless they have a bat issue. However, if you would like to fully fix your bat problem, rather than have another bat problem again, you obviously must protect against any bats from getting into your home / building again. Here are a few hints for totally bat-proofing your home so it will stay bat-free forever.
We are going to assume first that you have already gotten the bats from the building. Otherwise, you absolutely have to do this before you do some preventative work!
First off, you will need to do an inspection of the home. Pay special attention to roof edges, places where soffit meets the roof, fascia boards, loose tiles, vents, chimneys, and essentially any place in the structure where there may be a hole or a gap which bats can squeeze into. They can fit through regions smaller than you imagine - 3/8 of an inch, so make certain to check everywhere. The majority of the areas are going to be at least 8 feet off the ground or about two stories up, for the bats.
I have discovered that doing the sealup work at night helps. You may wear a headlamp and actually get a good look into all the little nooks and crannies. Plus, when you do the bat work, you may see the bats flying out, and back in, to the many openings, and this will provide you more info about where to seal. Tile roofs can be quite challenging. However, a fantastic sealup job with polyurethane sealant in each previous gap and crack are able to keep the bats out permanently.
The bottom line is that this is extremely detail-oriented work. Experience matters, and I do highly suggest calling a professional who has done many bat tasks to professionally and correctly seal the entire structure against any bat entrance.