Frank Bernheisel: The View From Here
Frank Bernheisel
Frank Bernheisel
Posted 01.15.11
Just Outside Washington


Geothermal Energy Usage Report

We have had a geothermal heating and cooling system working in our home here in northern Virgina since August, 2009 and we saw a drop in total annual energy use of thirty-one percent in 2010 over 2009.

Our energy use includes: lights, gas hot water, gas stove, gas fireplace, gas grill, electric washer and dryer, etc. These things we did nothing to change except replace some of the light bulbs with compact florescents.

For the comparison, I converted the therms for gas and the KWhr for electricity to millions of Btu and added the two together for the years 2008 through 2010. (I did not have December data so I estimated using last year; I will recalculate when the bills come in.)


As you can see in the chart, the peaks are down as is the total usage. Blue is the natural gas usage, pink is electricity and green is the total.

As mentioned above, annual useage of energy is down -- comparing 2010 to 2008 the decrease in use is forty-nine percent.

We have data going back a couple more years but I have not done that. We just had a bunch more insulation put in the attic and an insulated cover put over the pull down stair way to the attic. I am looking for that to make a difference in our energy use as will.

Estimated payback time: About ten years.

It's complicated. We have two systems in the house, one for the upstairs and one for the downstairs so we needed two replacement systems.

The upstairs air conditioning unit was failing and needed replacing. Also, there is a thirty percent tax credit on geothermal that we took advantage of.

Then there is the price of energy; we did the calculation with 2009 prices. I anticipate energy costs to go on up. Oil is now about $100 per barrel and I think we will see $150 in 2011.

We have not changed the house temperature overall but, because of the system change, we leave the thermostats at a constant 70 in the winter. The gas system we had drop to 65 at night but constant is better for the geothermal.

We drop the temperature in the bedroom by closing the door at night. The thermostat is in the hall outside the door so the hall stays 70 and the bedroom temp drops at night.

Like always, if we sit around we need sweaters.

Happy New Year to all, and stay warm.