While it is tempting to heat your living space with electric space heaters instead of turning on your furnace, the disadvantages outweigh the benefits. The Department of Energy states that a home or business owner who uses a space heater(s) to heat his living or working space will pay more than double what it would cost if a furnace was used.
People consider space heaters primarily because they think they'll be saving money by not turning on the home's furnace. This is a fallacy. In order to save money with a space heater, you'd have to keep moving it around with you from room to room. Each BTU of electric heat is about twice the cost of each BTU of natural gas. Consider the fact that gas rates are quite low compared to years past, and space heaters will become less and less tempting.
Those who choose to sacrifice their home-wide comfort will save some money by using a single space heater in a small area, but they must consider if the inconvenience is really worth it. For those who plan on spending hours in a small area of the home, a space heater makes sense. For those who live in larger homes and move from room to room throughout the course of a day or night, using the furnace is more comfortable and more cost-efficient than making use of space heater.
Yet many people who use space heaters tend to use them in areas that are already heated. For example, office workers tend to bring space heaters into their cubicles, which are already heated but to an unacceptable temperature. In this type of situation, the space heater makes sense. Unfortunately, people who use space heaters oftentimes forget to turn them off when they get up to do something else in the home. This creates a fire hazard and also results in an unnecessarily high electric bill. In summary, furnace use is optimal for homes where multiple people live and homes where an individual moves from one room to the next on a consistent basis.