I gave up on fans because they couldn't get it under 24 degrees in my flat. I had two 16 inch fans blowing in air through two windows....it gets up to mid 30s in the summer (i.e now) and I'm not really a hot weather kind of person. In order to keep it reasonably cool with the fan setup I needed two big windows open all day (I'm on the 3rd floor) which equals insects flying in, street noise, and nuclear sun blast when the sun gets round here so it became impractical and I was faced with the choice of sweating all day or listening to bendy buses and seagulls until I went mad.
I got a basic dual hose air con unit instead and I have it set to maintain low 20s depending on how I feel. It's about a million times better than a fan setup and also has a heater but I have to be careful not to leave it on all day of course....not that fans run for free either.