How to Tell if an Electric Space Heater is Energy Efficient: A Comprehensive Guide

When it comes to heating your home or office, energy efficiency is a crucial factor to consider. Electric space heaters can be a convenient and cost-effective solution, but not all models are created equal in terms of energy efficiency. In this comprehensive guide, we’ll dive deep into the various factors that determine the energy efficiency of an electric space heater, equipping you with the knowledge to make an informed purchase decision.

Understanding AFUE Rating

The Annual Fuel Utilization Efficiency (AFUE) rating is a crucial metric when evaluating the energy efficiency of an electric space heater. For electric heaters, the AFUE rating is typically 100%, as they convert all incoming electric energy into heat. However, it’s essential to consider the efficiency of electricity production, which is usually around 30% due to generation and transmission losses. This means that while the AFUE rating of an electric space heater may be 100%, the overall efficiency of the system is closer to 30%.

To put this into perspective, let’s consider a 1,500-watt electric space heater with an AFUE rating of 100%. If the cost of electricity in your area is $0.12 per kWh, the operating cost of this heater would be:

1,500 watts x 1 hour / 1,000 watts per kWh = 1.5 kWh
1.5 kWh x $0.12 per kWh = $0.18 per hour

However, when factoring in the 30% efficiency of electricity production, the true operating cost would be:

1.5 kWh / 0.3 = 5 kWh
5 kWh x $0.12 per kWh = $0.60 per hour

This example highlights the importance of considering the efficiency of electricity production when evaluating the energy efficiency of an electric space heater.

Heater Type and Energy Efficiency

how to tell if a Electric Space Heater is energy efficient

Different types of electric space heaters have varying energy efficiencies. Understanding the characteristics of each type can help you make a more informed decision.

Infrared Heaters

Infrared heaters are known for their targeted heating capabilities, directing heat directly to the objects and people in the room. This makes them highly efficient at heating specific areas, as they don’t waste energy heating the entire room. However, their effectiveness is limited to the areas they can directly target.

Ceramic Heaters

Ceramic heaters use a ceramic heating element to generate heat, which is then distributed through a fan. These heaters are generally more energy-efficient than traditional resistance heaters, as they can heat a room more quickly and evenly.

Oil-Filled Radiators

Oil-filled radiators are known for their residual heating capabilities. Even after being switched off, these heaters continue to radiate heat, making them a more energy-efficient option for maintaining a consistent room temperature.

Baseboard Heaters

Baseboard heaters are installed directly on the wall, providing targeted heating to the areas they are installed in. While they can be energy-efficient in specific applications, they may not be the best choice for heating larger or open-plan spaces.

Sizing and Heating Needs

Choosing the right size of electric space heater for your space is crucial for energy efficiency. A heater that is too small will have to work overtime to heat the room, wasting energy and increasing your energy bill. Conversely, a heater that is too large will heat the room too quickly, leading to frequent cycling and energy waste.

To determine the appropriate size of electric space heater, consider the following factors:

  • Room size (square footage)
  • Ceiling height
  • Insulation levels
  • Number of windows and doors
  • Climate and outdoor temperature

As a general rule, you should aim for a heater with a wattage rating of 10 watts per square foot of the room you’re trying to heat. For example, a 150-square-foot room would require a 1,500-watt heater (150 square feet x 10 watts per square foot).

Energy-Efficient Features

When shopping for an electric space heater, look for models that incorporate energy-efficient features. These features can help you maintain your desired room temperature while conserving energy and ensuring safety.

Programmable Thermostat

A programmable thermostat allows you to set specific temperature settings for different times of the day, ensuring that the heater only runs when necessary. This can lead to significant energy savings over time.


Some electric space heaters come with an auto or eco-mode feature, which automatically adjusts the heat output to maintain a comfortable temperature while minimizing energy consumption.

Multiple Heat Settings

Heaters with multiple heat settings give you more control over the amount of heat being generated, allowing you to match the output to your specific needs and conserve energy.

Programmable Timers

Programmable timers enable you to schedule the heater to turn on and off at specific times, ensuring that it’s only running when you need it.

Safety Features

Energy-efficient electric space heaters often come with safety features like tip-over switches, overheat protection, and automatic shut-off, which can help prevent accidents and reduce energy waste.

Calculating the Cost of Operation

To determine the true cost of operating an electric space heater, you’ll need to consider the cost of electricity in your area. This information can typically be found on your electricity bill or by contacting your utility provider.

Once you have the cost per kilowatt-hour (kWh), you can calculate the estimated operating cost of a space heater by multiplying the heater’s wattage, the number of hours it’s used, and the cost per kWh. For example:

  • Heater wattage: 1,500 watts
  • Hours of use per day: 4 hours
  • Cost of electricity: $0.12 per kWh

Estimated daily operating cost:
1,500 watts x 4 hours / 1,000 watts per kWh = 6 kWh
6 kWh x $0.12 per kWh = $0.72 per day

This calculation can help you compare the operating costs of different electric space heaters and make an informed decision based on your energy efficiency and budget requirements.


Determining the energy efficiency of an electric space heater requires a comprehensive understanding of various factors, including AFUE rating, heater type, size and heating needs, energy-efficient features, and the cost of operation. By considering these elements, you can make an informed decision and choose an electric space heater that not only meets your heating requirements but also maximizes energy efficiency and cost savings.

Remember, energy efficiency is not just about the initial purchase price; it’s about the long-term cost of ownership and the impact on your energy bills. By following the guidelines outlined in this guide, you can confidently select an electric space heater that will keep you warm and cozy while minimizing your environmental footprint and energy expenses.