Okay, okay, so technically, nobody's asking. But I am doing this as a public service today, in case you have found yourself in the position I was in a few weeks ago, frantically googling "what is a flood vent" in a desperate attempt to get my flood insurance premiums down to an affordable level. Because my insurance agent was helpful enough to mention that "flood vents" would reduce my premium, but he was not helpful enough to know what a flood vent was or how to install one.
And I found a ton of information via google, but most of it was put up by manufacturers of flood vents. Which was helpful, but naturally, these companies are pushing their own products, which are not cheap.
Here is the good news: You don't have to spend a ton of money on flood vents! All a flood vent is, is a way for water to flow unimpeded into and out of areas of your home (foundation, garage, etc.) that are in the flood zone. You need to have one square inch of opening for each square foot of area to be covered, and there has to be at least two openings, on two different walls, not more than one foot above grade, for each area.
Here is a flood vent!:
In the picture below, see that hole in the bottom of the garage door? That's another flood vent!
All you have to do is cut openings of the proper size, frame them, and screen them! That's it!
For more information, you can refer to FEMA Technical Bulletin 1 dated August 2008, "Openings in Foundation Walls and Walls of Enclosures". I'd link to it here, but I'm too lazy, so go ahead and google that. This technical bulletin has illustrations of the different kinds of flood vents, the parameters for which flood vents are acceptable, etc. Your insurance underwriter will probably want a letter from you stating exactly what you intend to do, the size of the openings, etc., and they may also want some pictures showing the installation.
There! I have performed my public service for today. You're welcome!