Fuel Efficiency: Most Efficient Fuels and Heating Systems

Fuel efficiency and the type and age of your heating system affect the quality of your home comfort. As a general note, natural gas and fuel oil are the most efficient and inexpensive heating sources of fossil fuels, in that order.

For cooking, gas stoves are more efficient and less expensive, but electric stoves win those categories compared to gas. The reason for this is that the electric ignitors in gas stoves stay on after the gas is turned on.

Below is a chart of fuel efficiency showing how much energy is produced by most of the conventional fossil fuels.

Note - the value for wood can vary depending on how “seasoned” or dry it is. Typical moisture content in aged, air-dried wood is 20%. Moisture reduces the energy value, and increases the soot value. A cord of wood is a rough measuring unit; it is a stack of wood 4 feet high, 8 feet long, and 4 feet wide.

Heat Content of Different Types of Fuel

How Much Heat Does Your Heating System Deliver from the Fuel?

Other than the fuel itself, some of the important factors that affect the efficiency of your system include its age, condition and all of its peripheral equipment such as duct work, pipes, valves, sensors, and even its location (whether it is in a conditioned or unconditioned space, and how far the heat needs to travel from its source to its destination). If you are replacing your heating system, then consider the following:

  • The type of heating fuel, its price now and its trend in the future,
  • The cost of the system, and its estimated life,
  • The system’s efficiency - which degrades over the lifetime of the system (usually 15-20 years)
  • The cost of maintenance.

If you have electric strip heat, then your cost is the baseboard and the electricity which is magically delivered from the utility, with little or no concerns for maintenance and fuel efficiency – that seems pretty simple, since electricity supposedly converts to heat very efficiently at the power plant, So, Is Electricity the Best Source For Heat? The short answer is that electric heat may make sense for moderate climates in a well-sealed home, with individual thermostatic control for each room, but only for intermittent or mild use. If you are replacing your system with a renewable energy system that provides you with a “free” source of fuel, then you only have the cost of the system to consider which is considerably higher than conventional systems, its maintenance, and its degrading efficiency over its lifetime.

Below is a table of estimated conventional heating system efficiencies as defined by ASHRAE (American Society of Heating, Refrigertation, and Air Conditioning Engineers).

Heating System Efficiencies

So, Is Electricity the Best Source For Heat?

From the table above, it might appear that the fuel efficiency of electricity is high and it is a clean energy source, but most electricity in the United States at power plants is generated by burning coal.

Coal emits sulfur dioxide, nitrous oxides, particulates, and greenhouse gases. Some electricity from power plants is generated from natural gas, which burns cleaner, but at least half of the energy is lost in converting it to electricity and delivering it to your home. The other downside to electric heat is that you lose heat when there is a power outage.

Generally, delivering fossil fuels such as natural gas, oil, propane to your home, or buying wood, or pellets and using a high-efficiency furnace or boiler is much more efficient to heat a home. But by far, the best fuel efficiency comes from renewable energy sources (wind, solar, water, geothermal) which produce no pollution when producing heat, cooling or electricity. This is not discounting the embodied energy which is the total amount of energy used to produce the solar panels, thermal collectors, wind mills, etc., nor the low system efficiency of solar photovoltaic systems.

A very viable option for electric heat is using it as a supplemental heat source in combination with a renewable heating system, such as a ground-source heat pump, or a solar, or wind system. Combine this with some added thermal mass in your home and a circulation system, (to store heat during the day and radiate and circulate it back at night), and you have a winning combination with high system efficiency.

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