Location really matters for bat houses. If you don't have bats after 5 years, you should consider moving the house. Generally speaking, they like heat.
This site has good info:
http://www.batmanagement.com/Batcentral/batboxes/choosingsite.htmlIt says that in southern locations, mount the houses outside, on a pole, back to back. That way when one side gets too hot, they can move to the other side.
