Power monitor

Over the last few years my wife and I have noticed out electric bill getting larger and larger. This is not surprising with the cost of everything going up, but what does bother me is that our usage of power has increased.

Why are we using more power? What is consuming the extra?

So in an effort to track down the usage, I purchased a Kill-A-Watt and started looking for the heavy hitters. The refrigerator, and the dehumidifier were all large as expected. But I was shocked at the Xbox we never use sitting turned off sucking down 60 watts.

As nice as the Kill-A-Watt is, it is difficult to test every thing in the house. And it only works on items that plug in to a wall outlet. How much does my 220V AC cost to run? What about the electric baseboard heater? And what does my electric usage look like as a function of time of day? The Kill-A-Watt just can’t answer these questions.

At about this time I listened to a fascinating program on NPR. They detailed the results of a social experiment run on a neighborhood  in I think England. They instrumented the homes with power sensors and for the first block of time (month?) they simply recorded the average household usage. The next block of time they provided feedback to the home owner via a glowing color ball; red for worst, yellow for average, and green for better. They found that a fairly large drop in power consumption with just this simple feedback.

The next block of time, the feedback was not based on the baseline power usage, but rather the average usage of the neighborhood at that moment in time. Now the power usage fell of even more. The heavy users changed their behavior and lowered the whole area’s usage.

During the last block of time, the feedback was not only against the neighborhood usage via the glowing ball, but the top ten highest users were displayed by NAME on an LCD display. To no great surprise, the power drop was shocking. People gave up amenities just to stay off the top ten list.

This was so fascinating to me that I decided I needed to install a whole house monitor. I contacted my electric company and was soon exchanging emails with the VP of conservation. He was interested as well. Pretty soon I had access to the database that shows the instantaneous power generation, transmission, and usage for the New England area. This would allow me to grade myself against not my neighborhood but my region.

Now I just needed to implement an electronic system to monitor power.

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