After installing all that new insulation this past fall, I’ve been curious to track how my natural gas usage might change for the better. A few other bloggers I follow have charted their energy bills lately and that seemed like the thing to do for me, too
I made a spreadsheet of the past three years of bills for both natural gas (boiler, range, and clothes dryer) and electricity. For each bill, I charted both the cost in dollars and the amount of energy consumption– therms for gas and kilowatt hours for electricity. Due to price fluctuations, the consumption figures are more useful for tracking any trends or changes in real energy usage.
The gas usage chart above includes only one bill from after the insulation was installed, so I’ll have to return to this in a few months to a year when I have more data for comparison. However, the chart already shows some significant variability during the winter months that I attribute to temperature fluctuation.
When I charted the electrical usage, I was surprised to find a 23% reduction in usage for 2009 compared to the previous year. I made the switch to compact fluorescent lightbulbs years ago and was stumped for an explanation for the decrease. Then it hit me: at the end of 2008 we started using a low-power netbook as the primary computer in the house and kept our old desktop pc turned off almost all the time.
Based on the cost savings for this reduction in kWh, the netbook has already repaid half of its purchase price– and it performs much better than the computer it replaced.
When I have more data collected on gas usage through this year, I hope I’ll find a similar cost-saving story about my new insulation.