Electric heaters are over 90% efficient, economical, are perfectly safe to use indoors or outdoors, and require little maintenance beyond periodic cleaning (unlike gas heaters). Electric heaters are also quiet, odor and emission-free, and are easier to use - just flip a switch. Another benefit of electric heaters is that you can easily adjust the heat intensity while most gas heaters only produce infrared energy on their highest possible settings.
Electric heaters are economical to operate. You can estimate your operating cost by multiplying the total kilowatts by your local power rate for a "kilowatt hour" (kwh). Your local kwh rate can be found on your monthly electric bill. For example, a typical 3,000 Watt (3 KW) heater, at full power, would cost 39¢ per hour based on a utility rate of 13¢ per kwh. Also keep in mind that your electric heater has a lower acquisition cost.
It depends on the region, but if you look nationwide, electric heaters are cheaper to operate than propane, and are competitive with natural gas heaters. Keep in mind that electric heaters normally have a much lower cost of ownership when factoring in purchase price and maintenance needs. Basically, while it may cost more per hour to operate an electric heater in some areas, it could take 7-10 years to save enough money operating on gas to recover the substantially higher purchase price and regular maintenance costs.
Infrared patio heaters are better If you are concerned about ambience, the appearance of your décor and creating a more relaxing environment because they provide a soft, warm glow that is practically unnoticeable while halogen heaters emit very bright and harsh-colored light.
Halogen patio heaters are better if you are looking for a more intense heat and don't care about the bright lighting that these heaters produce.