# A Smart Meter saved me money (just not the way BGE expected) [Letter]

A Smart Meter was recently installed on my house. I was skeptical as to whether this would help me save energy. As it turns out, I think it is.

I live in a house with heat pumps and programmable thermostats. I have long been leery of claims that a programmable thermostat would save me money. The theory is that if I turn down my heat at night I'll save money. The problem with this reasoning is that I have to turn the heat back up the next day, and I've always suspected that this process of reheating the house would use more energy than I saved by turning the heat down. My suspicion stems from the idea that it takes energy to change the energy potential, or the stored energy, in a system.

Think of the cruise control in your car. You get better gas mileage not by slowing down and speeding up, but by maintaining a steady speed. Every time you accelerate you use more energy than if you cruise at a steady speed. Would not the same idea apply to heating a house; wouldn't it take more energy to raise the temperature in the morning than you save at night when you allow the house to cool? Wouldn't a steady temperature be more efficient?

Until now I had no way to test my assumption, so I did what the literature suggests and used a programmable thermostat to turn down the heat at night and turn it up the next morning.

Enter the BGE Smart Meter. A few weeks ago BGE installed a Smart Meter on my house. I did not think that this would benefit me in any way, and I certainly read nothing good about Smart Meters in the press. Then BGE sent me an email that said I could log on to their website and see reports from the Smart Meter.

The first thing I noticed was that my house uses more energy than some of my neighbors and less than others. So what, I thought. But then I found a graph that showed my energy use and the outside temperature by hour. I thought to myself that this could help me answer my question about whether the programmable thermostat was saving me energy or costing me energy. I devised a simple experiment. I would add up the kilowatts used between midnight and 7 a.m. Then I would change the program on the thermostat to hold a steady temperature all day, pick a day when the weather was similar to the first measurement, and compare the number of kilowatts used each day.

As it turned out there were two similar weather days just a few days apart. The first night had an average temperature of 15.6 degrees Fahrenheit and the second had an average temperature of 13.75 degrees Fahrenheit. Upon adding up the hourly electricity usage I found that the house used 8.5 percent fewer kilowatts on the second night, the night that I kept the temperature steady, which also happened to be the slightly colder night.

My suspicions where confirmed; keeping the temperature of the house steady saved energy just like keeping the speed of a car steady saves gas, and I proved it with a Smart Meter. Your mileage may vary.

David Plaut, Reisterstown

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