Leominster, Massachusetts Geothermal Case Study with 2012 Operating Data

Hard to believe it’s been a whole year since we fired up the geothermal system in Leominster! You can read about the installation here. Right after Christmas in 2011, we installed a TED energy meter to monitor the geothermal electricity use. We monitored the compressor circuit and the fan/electric heat circuit for one year.  Here are the monthly and cumulative operating costs for the geothermal system in 2012:

That’s right – $200 to heat a 2,200 square foot house for one month!

Historically, this home consumed approximately 435 gallons of oil each winter and up to 1,000 kWh monthly for air conditioning.  The average price of oil in Central Massachusetts today is $3.684 per gallon, but has been known to exceed $4.00/gallon. Roughly calculated the heating and cooling costs, respectively would be as follow:

$3.684/gallon x 435 gallons = $1,602
1000 kWh x 3 months x $0.15/kWh = $450

Total heating and cooling cost before geothermal = $2,052

Mind you, $2,052 is the price for never being comfortable. $2,052 is the cost to heat and cool the house with large set-backs in the winter and with insufficient cooling in the summer. By switching to geothermal, approximately 46% annual savings has been realized when compared to today’s oil prices.

Now, suppose we apply a 5% inflation rate to both the oil and electricity price (which we feel is conservative considering historical fuel oil prices). The lifetime energy consumption costs for the geothermal system versus conventional oil and AC would look like this:

The savings exceed the cost of the geothermal system AND the homeowners are more comfortable, more often. How do you put a price tag on that?



  1. Russ Dunn says:

    re: “The savings exceed the cost of the geothermal system.”

    I assume the system purchase and installation cost was under $31,000 because the twenty year cumulative savings was $31,000 ($68,000 without geo minus $37,000 with geo). Am I reading this right?

    SO, is it fair to say the payback was 20 years? If not, what was the cost?

  2. admin says:

    The cost after the 30% federal tax credit was $27,500. Please also note that the $68,000 over twenty years is achieved by never being comfortable – too hot in the summer and too cold in the winter. With geothermal, they are keeping the house at a comfortable temperature all year round with minimal temperature setbacks. I would expect that by keeping the temperature warmer in the winter and cooler in the summer with a conventional system could raise the $68,000 by 10 to 20% – which would mean even bigger long term savings.

  3. Burke O'Neal says:

    Curious about how many SF the house is?

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