To reduce your energy cost for heating and cooling a home, efficiency is not the only consideration. You must also account for the cost of the fuel used. Hence we will talk about heating dollars which account for both. Electric heating is 100% efficient, however electricity is significantly more expensive than gas or oil per BTU. Below is a list of typical heating and cooling system efficiencies and fuel cost.
Fuel Type
Efficiency Range
Fuel Cost
Electric
100%
0.88k/Wh
Natural Gas
65%-95%
1.973/therm
Propane
65%-95%
2.390/Gal
Oil
65%-95%
2.49/Gal
Air Source Heat Pump
200%-400%
0.88/kWh
Ground Source Heat Pump
450%-600%
0.88/kWh
As you can see, the cost of fuel has different units of measurement, making direct comparison impossible. Further adding to the confusion oil and gas furnaces measure efficiency by AFUE, A/C by SEER, Heat Pump by HSF and ground source heat pumps by COP. While the calculations are not complex there are many. In fact the Home Energy Tune uP uses over 100 data points specific to the home and performs over 1000 calculations to arrive at the improvements and upgrades it recommends. Manual calculations often lead to errors, significantly reducing results.
Efficiency
You may have notice that Heat Pumps and A/Cs have efficiencies greater than 100%. How can that be? Energy cannot be created. With oil and gas furnaces/boilers a fuel is converted to heat through combustion. Although some furnaces and boilers may have efficiency ratings as high as 97%, they will never reach 100%. Electric resistance heating is 100% efficient. Converting all electric consumed directly to heat.
Heat Pumps
However Heat Pumps and A/C systems do not create heat, they transfer heat. When in heat mode, heat pumps get their heat from the outside and transfer it to the inside of the home. The reverse is true when cooling. Heat is transferred from the inside of the home to the outside. The electric energy required to transfer the heat is significantly less than the electric energy required to produce the equivalent heat. Hence efficiency is greater than 100%. In fact a HP with 400% efficiency will use only one fourth the electric compared to electric baseboard heating, more than offsetting the higher cost of electricity.
Heat pumps become less efficient as the outside temperature drops. Depending upon your system efficiency (higher efficiencies can provides heat with lower temperatures), heat pumps become less efficient than pure electrical resistance heating. This is why most heat pumps sold in this area will have electric heat strips built into the air handler or have a gas furnace. This is the “Aux” or “Emergency” setting on the thermostats of heat pumps.
For this area the number of days below 35 degrees is limited making the heat pump economical. Therefore, a home heated by electric baseboard heating can significantly cut the cost of heating by installing a heat pump. In addition the home owners gain A/C and an increase in the value of the home.
This is the beauty of the Home Energy Tune uP report. All calculations for efficiency, fuel cost, are converted to Energy Dollars for you. You are shown the dollar savings and how much they cost to install. This makes your decisions much simpler. Often home owners will make costly improvements like windows which may take 30 years or more to pay back with just the energy savings. The Home Energy Tune uP report will show you which improvements and upgrades are most cost effective.
