First 12 Month Legacy House Energy Results

The first 12 month’s energy consumption and cost numbers are tallied. While I was disappointed with the raw percentage solar, the projected annual cost came in just a little higher than expected for the house. The HERS (1) estimate was $950, and we ended up at $1058.67. But — (and BIG but) that annual cost includes one year of driving our electric car. Because the HERS calculations on our basis document do not include a car, as nearly as I can figure we are doing better than expected on total building energy useage, which I really thought we would. The data is below.

We do have Sense monitoring equipment on the house and on the garage, so it is possible to make an educated guess on the amount of power being used by the car. An educated guess only because the Sense gear cannot combine data from the two devices and only one of them is tracking the 20 solar panels. Very confusing. I do not recommend Sense for anything but simple single sensor installations. In any case, if we throw out the solar assuming that it was split proportionally between the car and the house, the educated guess is that the car is using about 1/3 of our juice. If that is so, the house annual energy bill is about $705 and the car annual energy bill is about $353.

The spreadsheet above shows that winter energy consumption is higher, and that central Ohio is a cloudy place during fall and winter. No big surprise on either point. We had originally planned for 24 solar panels, and that might have been a better choice, but we thought we’d wait and see how things panned out. I think we’ll wait another year before putting panels on the main house (just on the garage, now). If we do that we’ll probably go to 28.

We have made some other little changes that may show up in the next 12 months. The hybrid water heater has recently been switched from hybrid operation to heat pump only operation. We see no difference in hot water availability, and that should reduce power use. We have also switched to a renewable power generation supplier. That lowered supply costs a bit and makes us totally renewable.

-George