Variable Speed Ceiling Exhaust Fan - I assume you are a DIY and have determined that putting ceiling fans in your home makes good sense.
In the chilly months, so that they push warm air down in the ceiling reversing the fan blades can lower your heating expenses also.
So, you're sold on the idea of installing ceiling fans. Another step will be to decide what brand, style, etc. you're going to invest your money in. Do the research. Find out the length of time they have been at it and who the important players are in the manufacture of ceiling fans. It is not always who sells the most ceiling fans but rather, what consumers say about the different brands. The Net might help but you have to be cautious about sales pitches which can be disguised as testimonials.
Nevertheless, before I get off the niche of what to purchase, a word or two to the shrewd. That is not a purchase you want to make with the notion of saving as much money as you can on these units. Makers of affordable units have become more adroit at making their products look excellent and more.