The weatherman says that this July was the eighth hottest month since they began keeping records!  That begs the obvious question on everyone's mind:  What does that have to do with me?

The bottom line is that our record-tempting hot July cost us money.  More specifically, it cost me approximately $10.23.

I've been recording my daily power usage and the high temperature for the day to see what correlation exists between the two.  Obviously the air conditioner runs more when it's hotter, but now I'm able to quantify that relationship. 



This graph shows that as the daily high temperature increased, my power usage also increased.  I was surprised at how closely the individual data points follow the trendline.  (I'm looking forward to this winter when I can complete the left half of the smiley face!)

The average July high temperature for Charlotte is 90 degrees, but this year it was 93 degrees.  That doesn't sound like much, but those three degrees have a big impact on my power bill.  Interpolating from the graph's trendline (and indicated by the red lines), at 90 degrees I would use 36.2 kWh of power; and at 93 degrees, 39.5 kWh.  So, our hotter July forced me to use 3.3 kWh of additional electricity each day.

At my rate of about $0.10 per kWh, I paid (3.3)*($0.10) = $0.33 more per day this July than I would have in an average July.  Multiplying that by the 31 days of the month gives me a total extra cost of $10.23.

I'm not sure how useful this is, or if it's useful at all.  But I do think having a better understanding of our power bill is the first step toward reducing it.  When you hear those advice-givers say to set your thermostat a few degrees higher to save money, this is what they're talking about.  Three degrees would save me about $10.  Or, if you want to double your money, six degrees will link you to Kevin Bacon!