Ok hang on to your hat for the odd option.
Marine CAFRAMO Sirocco Cabin Fan, cost about $80 each, wall mounts, draw is 0.3 amps on high and 0.14 amps on low with a capacity of 240 cubic feet per minute.
That's just the one I like. There are a bunch of cabin models sold for marine applications. Marine applications are a lot tighter than typical recreational fans in that they need to be more efficient so less battery draw due to infrequency of charge times. They're used on oil rigs etc.
As some general advice from someone who uses battery gear for extended periods a lot, consider an inverter for as many options as it fits. DC current the length of wire and size of the wire addes a lot of resistance thus amperage requirment to do the same task. Also a good inverter will have a low voltage alarm for delicate electronics that doubles as an alarm to warn you either time to recharge or conserve on power draw. I'm not talking about a whole house either. My boat is only 25' and like a one room apartment. It made a significant difference in battery time.
Hand held watt meters are inexpensive now including DC models. They're worth their weight in gold on this type of thing. You will need to read that it does do DC. I think I paid $60 for mine. Anyway, they're on Amazon. They're basic volt meters too so you use them all the time for a 1,000 different things.
In general, this type project is like packing a BOB. You want to go as light as possible to begin with then you end up shaving ounces, in this case amps/watts while adding and subtracting here and there. Amps=watts/volts. Shake it as you need it.
Now here's the Catch. You can calculate what you think you will use then when you use it, everything changes. This is the same as BOB again. You gotta use it to really know. The problem is nobody uses a power routine down to minutes. What you end up doing is thinking in longer time frames and what is typical over a period of time. For example, using whatever I want which is usually Marine radio and depth finder on 100% of the time, fridge on 100% of the time, lights and water as needed, stereo on most of the time, movie system of some sort a couple hours, and fan on all night, I get 24 hours on two 1,000 amp batteries without setting off my voltage alarm. Once that happens, I need to either start switching things off to conserve or switch my battery bank to recharge some. I'm not saying operate your safe room like a boat, you could, but that's not what I'm saying. Its think like that, how long between charges and try not to tie it down to minutes so that you have flexibility.
The bigger decision is how do you see your safe room being used? One night storm event, criminal event, and long term event are all totally different preps. Things I like are I really like my battery operated TV. In a storm event that has me in my safe area, it provides live TV coverage of the radar tracking that the family can watch without running down the battery on my phone. I like having a recharge method for my phone. I like comfort items, water, food, blankets, pillows, seats, beds, etc. A biggie is the ability to use the bathroom. Keep in mind, keeping the family occupied in such emergencies is a very big deal.
I have a ton of stuff in my home. I can light up the outside like daylight at the flip of a switch, all LED now so I can leave them on longer, I can live in my below ground level for six months without giving up much of anything, but the neatest thing I have added in the last few years is my Alarm system. Damn have these things come a long way. I use Simplisafe. Its low cost and wireless which means it does not depend on the power being on, at least not short term it doesn't. What this means to a safe room is you can have all the features of the movie "Panic Room" in a closet without major expense or rebuilding your house. The lowest cost option is a "Panic button". Hit the button, it activates the alarm sequence including calling the police. Man, wouldn't it had been nice if Jody Foster had that? Pay some more bucks, you can monitor your home via you cell phone not just from your safe room but anywhere you have phone service. I've set my alarm off twice now by accident and wow where I live is it fast. They call right away, no code word they call the police, and the police show up at my place in ten minutes. Like Onstar in a car, if you talk to them they can send ambulances etc. (Check your area on if there is a local fee for alarm system calls. There's not in mine.)
Mostly we use our safe area for storms. In this, you will use it much more and be more safe if you make it as close as you can to "Let's just all go in here" like you were simply changing rooms. That means keeping your comfort level high, keeping your comms up, and keeping everyone there because Mr. Murphy will guarantee its when you go to get soft drinks or whatever is when your house goes all Wizard of Oz.
I know that's more than you wanted for a fan but they're all tied together. Power draw is a big part of it.
Tj