Its time for the two fuel sources to play fisticuffs and battle it out to see who is really more efficient for our climate and what is often the best fit for your home. The results may surprise you because with the new technology available its not as simple as it used to be.
Lets start with natural gas, the reigning champion of heating since it unseated oil heat in many parts of the country in the 70's and 80's. Natural gas has been a staple for many new homes heating systems and with costs currently around $1.00 per therm(100K BTU's) it has a relatively low cost. It can be used for cooking, clothes drying, water heating and of course heating your home. The best furnaces today are in the 97% efficient(AFUE) range compared to older 78-80% furnaces. This means that for every dollar(around 100K BTU's) you get 97K BTU's into your home and only 3K BTU's going out of your chimney. With recent finds of new sources of Natural Gas in North America there is plenty of supply, but how difficult and how much impact there is to get it out of the ground is yet to be seen. Another downside to natural gas is that it currently can not be generated on your own property, do you know anybody with a natural gas drill rig in their back yard? Neither do I! So for a typical home with a $1,680 per year gas bill and a 92% efficient furnace with a $1.20 per therm price they use around 123.7 million BTU's per year.
So lets talk about electric heat pumps, just like gas furnaces, the efficiencies can range from minimum standard(7.7 HSPF) to high efficiency(10+HSPF) HSPF stands for Heating Season Performance Factor and is essentially the COP of a heat pump seasonally adjusted. So what is a COP? COP Stands for coefficient of performance, so its a little like a % rating, but since a heat pump is over 100% efficient it gets stated differently. The highest efficiency ground source heat pump is up to a 5.3 COP or 530% more efficient than electricity. The highest efficiency air source heat pumps are in the 4.5 COP range or 450% more efficient than electric. The problem is they are rated at a specific outdoor air temperature of 47 degrees, so when its warmer they are more efficient and when its colder they are less efficient unlike a gas furnace that is 97% efficient nearly all of the time if sized properly. So getting back to HSPF lets say we have a 9HSPF heat pump(needed for most rebates) we can divide 9.0 by 3.413(number of BTU's per watt) to get a seasonal average COP of 2.63 or 263% more efficient than standard electric. You can already see that it is hard to compare natural gas to a heat pump and while the results are coming, I want you to see why many others may not offer a heat pump, because they don't understand how they work and understanding how they work is key to knowing what is best for your home.
Using the same 123.7 million BTU's for a home and a cost of $.11 per KWh for electricity we can figure out that it would take 36,243 KWh of electricty or $3,986 to heat the same home. However since we are running at 263% efficient the cost to heat the house with a heat pump would be $1,515
The heat pump would cost around $165 per year less, and if the home did not need the gas meter or did not currently have a gas meter that would save them another $8 per month or $96 per year additional. Electricity can always be generated by solar PV that is available for many homes and that would drop most costs to operate a heat pump to only $1,200 per year if you lease a solar PV system with $0 down. A heat pump both heats and cools and provides better air quality with more even temperatures for most homes.
So which is the winner? It still depends on your home but with all things considered for a mid efficiency heating system a heat pump is going to be the lower cost to operate system and if you don't currently have gas in your home, then you will save an additional $96 per year by not needing a gas meter.
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