The blue line is my original house with electric resistance cable heat in the ceiling. The red line is the new house which is larger in area, but better insulated with 2x6 exterior walls and spray foam insulation, and geothermal closed loop heating system. The houses were within 5 miles of each other so both were in the same climate. Some trends here are pretty obvious, in the winter when it's cold out and you use electricity for your heat source you're going to use a lot more of it. There's also more light usage during the shorter days, but I think most of the difference is in the heating. Also the new house has about half the winter usage, but is similar in summer usage. What happened in 2005 when summer usage doubled? That was when I got married and was joined by my beautiful wife in the house who apparently uses about 500 kWH per month by herself. (As a side note if you make similar measurements don't bring it up, your spouse will not find it interesting). There may be some winter effects of keeping the house warmer than I did by myself in there too (Also a touchy subject).
Cost is a similar story although you can also see the gradual rise in energy costs over the years. I heard a lot of horror stories before I bought the house about the cost of electric heat. Although it was by no means cheap, I don't think it was much different than most people's natural gas bills in the area.
Where does all the electricity go? To find this I used two devices, a killowatt plug in meter and for devices that are hard wired The Energy Detective (TED).
http://www.p3international.com/products/special/P4400/P4400-CE.html
http://www.theenergydetective.com
Not surprisingly home heating was by far the largest user of energy even with the geothermal system, next came the clothes dryer,hot water heater, and than an old chest freezer we have in the garage all around $10 per month each. One surprise was a water cooler fountain we were using in the kitchen, it was making both hot and cold water (although both in small quantities) and cost nearly as much to run as the freezer and more than the kitchen refrigerator. Things like the computer desk, television, and oven were in the $5 per month range. Commonly used lights tended to be a dollar or two per month. I'm careful not to leave any lights on 24 hours a day or overnight, as that would start to add up quickly especially if they were 100 watt floodlights like you commonly see. Occasionally there will be news articles about "vampire" loads in cell phone charger power supplies. These things cost pennies a year, you can worry about them if you think it will help the environment, but they aren't going to save you much money. Use your money for better insulation or a more efficient furnace.
Here's an interesting chart showing how the outside temperature effects the cost of running the furnace or air conditioner. Obviously the colder or hotter it is outside the more energy it will take to maintain the indoor temperature of the house. A side affect of the furnace or air conditioner running often is it will start using the desuperheater to heat the water going into the hot water heater. In the summer this is pretty much free energy it is taking out of the indoor air. In the winter it isn't quite as good deal, but it's still more efficient than the straight resistive heating of the conventional water heater. So the result is the more you pay to heat and cool the house the more you save on hot water. It never will pay for itself, but it is substantial. Once it gets below 20F or above 90F I'm pretty much not paying to heat any water.
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