Electric heaters are usually sold as portable models that can heat the room you're in, while saving energy by not heating the other rooms in your home. Electric heaters vary from model to model. By comparing the efficiency of each, you can save even more energy. Unlike portable gas heaters, electric heaters don't need vents and can be used in any type of room with an outlet, even if it's enclosed. These high efficiency heaters are the safest options when it comes to portable heaters.
Measure the dimensions of the biggest room where you plan to use the heater. Decide the maximum amount that you want the heater to increase the temperature in that room, and plug that information into an electric heater sizing calculator, such as the ones available at heater-store.com and tombling.com or one provided by the company where you are buying your heater. By doing so, you can rule out heaters that don't meet your heating needs and you can avoid buying one that isn't efficient enough for a small space.
Check to see how much time it takes the electric heater to heat up. Many brands will advertise this period of time on their website or packages, but if not, you can compare wattage, with the most watts equalling the most power and the faster heat-up time. However, higher wattage models use up more energy than lower wattage models.
Compare types of heaters available within the wattage range you calculated in Step 1. Then compare models within each type. Each type of heater is designed for a certain environment, which can cut down on the number of models you need to compare. Convection heaters usually offer the highest energy efficiency for larger spaces, but if you're using the heater in a small space with one or two people, a radiant heater is a more efficient option. Fan-forced ceramic heaters can be efficient by only directing heat toward one area of a room, while panel heaters save energy by not using a fan.
Pay attention to the controls of the electric heaters you're comparing. Those that have easy-to-use thermostats tend to be more efficient because you can control the exact temperature in your room, meaning you control the amount of energy being used.