The cost of running a 48 ceiling fan on high 18 hours a day will cost around $5.82 a month which means that unless you have more than five ceiling fans in your house running simultaneously you'll be saving money on your energy bills.he cost of running a 48 ceiling fan on high 18 hours a day will cost around $5.82 a month which means that unless you have more than five ceiling fans in your house running simultaneously you'll be saving money on your energy bills.