There is basic difference between a good bat house and a structure that bats may use. A good bat house (or bridge, or mine, or artificial cave, or whatever) tries to mimic a good roost and meet the basic requirements of the bat's needs at that time of year, usually in the summer for a maternity colony of bats. The most important are temperature (critical!), especially warm temperatures, crevice structure (size [3/4" crevices] and substrate [gripping surface]), protection from predators and human disturbance, and so on. Well-designed bat houses (or artificial caves, or bridges, or whatever) will easily attract a good colony of bats, and there are numerous examples ranging from the D'Hanis bridge on US 90 to Bambergers artificial cave (the "Chiroptoreum").
Where a lot of people make mistakes is looking at what is being used by desperate bats. Bats will indeed roost in almost anything, but will they have long-term survival and thrive as a colony? A huge number of consumer-grade bat houses available out there (from bird stores and home stores and garden centers) are just plain crap. They might be suitable for the random bachelor male, but would never accommodate a maternity colony of females and young. Like I said in the earlier post, I don't know any details about the new UK bat house, so I am not even going to speculate about its efficacy. But my gut feeling is that the openings are entirely too close to the ground, making entering/emerging bats very susceptible to predation, at least from house cats (I have no idea what other predators may be in the area), and that the structure is going to be far too cool in that climate for a maternity colony. The latter could at least be rectified by painting it dark brown, or even black. There is a reason that bats prefer to roost in attics and church steeples instead of basements. It's the warmest there, due to the hot air rising. Even here in central Texas we need to paint out bat houses at least a medium dark shade of color to help them warm up. Enough about bat houses. All this information is (and has been for years) on BCI's excellent website. The bat house info specifically is at http://batcon.org/index.php/get-involved/install-a-bat-house.html -- Jim Well, Jim, as we all know, bats seek out some pretty strange places to roost--bridges, attics, underneath siding, caves, etc--so if they have some place to cling, maybe this will all work out for them. But as with any real estate, it's location, location, location.
