In praise of the TerraPass home energy calculator

intern.jpgOur summer intern, whose name we can’t quite remember, was particularly wounded by one graf buried deep in the SF Chron article:

Of the sites listed below, Terrapass’ calculator has the most specific information for flying and driving…However, its home energy calculator isn’t as specific as those on many other sites.

Oh, the injustice! Tim was the manager of our Home product, and the calculator is his crown jewel. We invest a lot of effort into the accuracy and usability of our calculators. And of the three on our site, the home energy calculator stands out as by far the most data intensive and complex.

The problem, I gather, is that Ted put a little too much though into ease of use, and the simplicity of the interface fools people into missing the magic behind the scenes. Whereas many online calculators ask you for rough proxies of energy use, such as the number of rooms in your house, our calculator asks you for your actual utility bills, a much more precise measure of energy use. Not only that, we measure four different energy types: electricity, natural gas, heating oil, and propane.

The calculator then does two things with the info:

  1. Your most recent utility bills are extrapolated to an annual value, based on the region of the country you live in. We have data for every ZIP code, and know, for example, that energy use in Phoenix is highest in summer because of the air conditioning load, whereas energy use in Seattle is higher in winter.
  2. The value of your energy bills is then translated into annual carbon emissions, based on regional energy prices, and, more importantly, the carbon intensity of your local electricity. Carbon intensity can vary by a factor of more than ten between, say, coal-powered Wyoming and relatively renewable New York.

But, wait, there’s more! If you’re not happy with the resulting estimate, you can further finetune it by entering utility bills from different months or entering exact values for items such as gas usage.

Which is all a way of saying: Travis’ calculator is very, very fancy. Check it out.

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  1. LochDhu - November 8, 2006

    My gas company, Dominion measures in MCF. Your calculator only accepts Therms. A quick Google revealed MCF = 10 Therms. You should allow users to enter in either unit of measure.