For a permanent fixture theres nothing wrong with the kalgoolie fridge concept. all thats needed is a tub to hold the water a few hessian sacks, a elcheapo water pump and a fan or 3. Install it low down so the tank is on the outside and the fans inside. Then a nice cool breeze from the fans will push the hot air up and out thru a high place open window.
OK won't work in real high humid places but it works fine here in summer where we have a dry heat.