It can easily reach into the upper nineties and the lower hundreds here in St. George Utah. So with summer in full swing many of you are seeking out cost efficient ways to cool house. You may be wondering what costs more, running a fan all day or the air conditioner?
It depends, but here is some helpful information to help you muddle through.
A fan uses electricity to circulate air around a room. This makes a person feel cool because it causes the sweat to evaporate quickly. Evaporating sweat makes a person feel cooler because that was how we evolved to feel cool. It is more effective than even slight colder air temperatures. This allows a person to have a tolerance for slightly higher temperatures. This is called a windshield effect. It makes a person feel cool, but it does not actually cool a room.
An air conditioner, on the other hand, uses electricity to physically cool the air entering a room. Contrary to popular belief an air conditioner doesn’t actually work fast when the thermostat is turned down several degrees. The system merely works longer and shuts off when the desired temperature is reached (Myth Busters: 8 Ideas about energy efficiency debunked). Using a programmable thermostat is the most cost effective way to use air conditioning, because it regulates the use of electricity while you are gone, ultimately saving up to ten percent on your electricity bill.
Keeping a fan on in a room that is not in use in conjunction with air conditioning can actually increase your bill. The fan does not cool the room it makes people feel cool. The walls and ceilings of a room are warmer than the interior; the circulating air caused by a fan mixes this warm air more effectively with the rest of the room. Ultimately this causes the room to warm up faster than if the fan had not been on. This makes the air conditioning work harder with none of the benefit of the fan.
Using a fan in conjunction with the air conditioner can save you money if you raise the thermostat by a few degrees. The fan will make you feel cooler than the air temperature, raising your tolerance by a few degrees. The air conditioner will not have to work as hard to cool the whole house to a lower temperature and you will feel just as relieved from the heat of the day.
So in the end, it depends on a few variables. Do you only want to cool one room of the house, or do you only want to feel cooler by a few degrees? Than a fan is the more cost effective choice. Do you want to cool yourself and the rest of though house by several degrees? Than an air conditioner, in conjunction with a fan will do the job of staying cool in St. George quite nicely.