I have to say, seriously, Stegve has a good idea! Find out what kind of birds you have and find out what type of nest(s) they like. Birdhouses may be just fine. Oh, and if they don't use birdhouses, make sure that the nesting material is 'around' for the birds to use to build their nests.
Moving right along, ... This article is ALL over the WEB. Wasp Control - Read it in its entirety. The article addresses wasps behind shutters and such.
As a last resort, I have a far-fetched option. Wasps, like many insects and bugs, like certain 'living conditions' in order to nest. If you have black shutters, sometimes painting them a lighter color will 'cool' the sutter down and cause the temp behind the shutter to drop. I know that this idea may involve repainting the trim on the entire house but it may just work. Look into alternative materials for your shutters too. Today, they're made of vinyl, aluminum, wood, and composites. Each of them absorbe, and shed, light and heat at different rates. Again, changing the 'conditions' a little may be enough to rid them.
Before I installed our vinyl siding, we had black aluminum shutters with the nesting problem. (I just never knew it until we did the demolition!) Anyways, we now have black vinyl shutters. Guess what??! No more wasp nests. Our home faces South too. Maybe it's TOO hot behind them for wasps to nest, I don't know. That's where my 'idea' (above) comes from. I, like you, now check them a lot (from the upstairs windows.) I have a child and we do open our windows (that have screens in them.) They do manage to come in even if you have screens through the weep holes. It's been 4 years now and NO wasps in the house. We always use to wonder where they were coming from, but no more.
Well, I think I've said enough. My best to ya and hope this helps.