I would see these humongous units of Iwata Evaporative Airconditioner in stores. They would turn on their air conditioning unit and use Iwata as something to augment the coolness of the place. Its purpose really is to support the air conditioning, not to become the main source of cold air. Indoors, it is quite noisy and takes up a lot of space.
But in our case, our home church bought a couple of units. We have moved to a bigger location but without airconditioning and it can get really hot. It is actually a school auditorium so the place quite big and we are only using the front half. Having electric fans is not enough. So the church board has decided to get a couple of units of the Iwata Evaporative Air Conditioner, model KF-35.
I am not sure about the technicalities, but it sure did help alleviate the heat in the place. We don't have a problem with the unit being big because we are in a big space. Regarding noise level, it is negligible, after we have our worship service in an open space.
The only problem though is that although it can cool off a big area, it does not oscillate unlike the electric fan. So there are certain areas that could not be reached. These areas are then cooled by smaller fans.
I just think though that this unit is pretty expensive. I am not sure about its electricity consumption though. Because given the choice, I will still buy and airconditioning unit.