Saving energy with a netduino – results

Bamboo Leaf Collage

Back in February 2011, I built an automated gas water heater regulator using a netduino micro-controller to save some energy with our old gas water heater. There was much debate among Hack A Day and Channel 9 readers about the effectiveness of this hack and its ability to actually save energy.  As promised, I am now reporting the results of the experiment.

Puget Sound Energy, our energy provider, is kind enough to track our energy consumption and makes the data available through their web site. I ran two reports to compare our natural gas usage between March and April 2010 and the same time period in 2011, including the outside temperatures.

Puget Sound Energy Charts – Natural Gas Consumption

March-April 2010

March - April 2010

March-April 2011

March - April 2011: With Hot Water Heater Controller


Compared to 2010, the netduino-powered Water Heater Controller saved 20 therms between March and April 2011 even with lower outdoor temperatures than the previous year. In WA a therm costs ~$1.19. So this represents a $23.80 saving. Not bad for a weekend project 🙂 I wish I had more data to show, unfortunately, the water heater died on us the second week of April with a completely rusted out bottom. C’est la vie…

Death by "rusted out bottom"



  1. Pingback: Windows Client Developer Roundup 072 for 6/13/2011 - Pete Brown's
  2. David Ray · June 30, 2011

    Ack! Proof that Netduino causes rust!!!

  3. me · February 11, 2014

    This is a fascinating project. In your original post you noted you put an external insulation blanket on the water heater right after you finished the project. Did you have this blanket on the water heater in March – April 2010 also? If not, I suspect most of the savings are due to the addition of the blanket but would be very interested to know.

    • Fabien Royer · February 11, 2014

      No, an external insulation blanket was never installed on that old water heater, even though it was suggested as a potential mitigation.
      The power savings were realized only by regulating when the water needed to be heated.

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