Earlier this year I began putting together some information to track our average daily use of electricity. I wanted to know if having central air versus our window units had made any difference and also if our new compact florescent lights were doing much. In the last couple of months, our electric budget bill was adjust down from $126 to $102 per month. Of course, since that’s also based on the cost of electric and not the real usage, I dug further to see how we were really doing.
Here’s what we’ve looked like over the past 2+ years in our home (avg kWh/day):

So, we moved into our house in June of 2006. Back then we had window air conditioners for our 2300 square feet. They were old and noisy and we used them sparingly. We willingly opened the windows when we had the chance. In May of 2007, we had a central air system installed. Since it works best to remove humidity from the air, we don’t open and shut the windows as freely, so it stays on longer. Notice 2007 started it’s peak earlier and it lasted longer. It was then our budget bill went from $104 to $126.
Now, early 2008, we replaced a number of our well used light bulbs with compact fluorescent, and we made the decision to raise the temperature of our central air by 1-2 degrees this summer. Luckily as well, the temperature this summer seemed to be much more moderate. Combine that with and earlier vacation (September rather than October) and our real electric use has been way down this year.
In case you don’t realize, we have a natural gas boiler that runs our radiators, so we don’t use much electric in the winter. The “central air” is actually a heat pump, so it can provide some heat. However, we use that as a back up system that is more of a signal that the pilot light is out on the boiler, you better go re-light it! If we notice the heat pump kicking out heat in January, we know something is wrong.
There’s several more things I’d like to do to make this number look even better next year:
- Replace more bulbs in the house with CFLs
- Update some of the electrical system with properly grounded and wired outlets
- Replace the rest of the power supplies in our computers with lower wattage and higher efficiency “green” power supplies
- Rearrange some electronics and things to allow for more visible power strips so we can easily turn the television and all the associated stuff completely off when we leave the room, rather than leave clocks and wireless networks drawing power constantly
Of course, we should really do this same sort of thing with our gas usage in the winter, though it’s a bit more challenging. We use practically no gas most of the year (water heater and range) and then use a ton of it during the winter months with our 80 year old boiler. It was converted from coal to natural gas years ago. I’m sure the boiler is somewhere around 50% efficient, but the replacement cost can get pretty pricey. I looked and just buying a 95% efficient boiler was going to run $3k or so. And I’m sure installation is at least that much if not more. Even if that did cut our gas use in half, that would save us like $80-90 a month. It takes a looong time to pay back five or six thousand dollars if you are paying that much a month.