Electricity Data: The Devil is in the Details

I have written several posts about the Smart Grid recently, both here and on my personal blog. I got an email from a man in China today, as follows:

Hi Tom,

You are running a fabulous blog, and the discussions are rather helpful. [Ed Note: Entirely gratuitous reference to author's blog :-)]

Well, I have one question, how do you compile the curves of the electricity consumption in the last four years ? You get the historical data from your utility at a fee, or you have installed the meter yourself ? Making a day-to-day, and year-to-year data can be exhausting, but it is absolutely necessary.

{email and name}
Assistant Director, CEM China Team

Association of Energy Engineers CEM Program

His email was in reply to the data I have posted on how we have reduced our electrical consumption a great deal -- to date more than 1/2, and at the time a bit less than that.

Here's my reply (in which I have included some links and some headers):

Samuel --

Thanks for your inquiry on my electricity reduction data as posted on my blog at FivePercent [Ed Note: entirely gratuitous self-promotion on the part of the author]

Reading Your Utility Bills

The data are from monthly bills based on meter readings, provided by my electric utility, free, as part of their service. The bills include the meter-read date, so I am able to calculate the average kWh/day for the measured month.

Our utility provides 13 months of meter data on each paper bill, and also provides historical views of bills (pdf files) going back several years, although most of the data was copied from the paper bills I had saved. The data as presented is simply a chart of the month-over-month kWh usage, compared on a year-over-year basis. This pattern was the most useful representation of the data because there is a natural pattern of electrical use in our household correlated primarily to the number of daylight hours, and secondarily to a small amount of electrical heating we do in the basement (the rest is natural gas).

Recently, the utility has begun providing the calculation of kWh/day of usage on the bill -- good for other customers, since the other data provided do not normalize for the length of the billing cycle. For example, I got our bill today for the prior period and was alarmed to see a large cost compared to the previous month (for which they provide a bar chart), but then saw that the billing cycle was 34 days compared to 29 the previous month -- it the end, our consumption was slightly down on a day-by-day basis.

Real-time Electrical Meters

We have installed an ancillary meter that provides near-real-time usage data via a wireless display monitor in our kitchen. Our device is designed to read data from the electricity meter at our house, using one of several possible methods, depending on the meter type (none involving smart meters). Another widely available device in the US and UK is called "The Energy Detective" or "The Owl", which work by measuring the impedance on the incoming A/C feed. The would be much more accurate and immediate. But in neither case are these meters used to actually calculate our bill -- they are just a way to get at that critical momentary data. However neither device provides a data recording mechanism, so all you can see is how much you are consuming now.

Evil, Evil Level Billing

The momentary data from the real-time meters is far, far more useful than a monthly bill, which you rightly point out is of little value to the typical electrical consumer. However, there's a practice in the US, at least that further disguises the actual usage, known as "level billing". Consumers who choose this method pay a fixed monthly rate based on the average consumption of the prior year. The rate is adjusted up or down based on actual consumption on a yearly basis -- in effect this is a financing mechanism offered by the utilities. In reality, this further masks the cost of energy beyond the already overly-aggregated data on the monthly bill.

Smart Meters

Smart Meters are clearly superior in every respect, assuming the electric (or other energy) utility, or even an intermediate data aggregator, is able to store the data as a suitably fine level of detail (e.g. 15 minute intervals) and also provide reporting tools that allow customers to understand and visualized their energy usage, both in aggregate as well as momentary data. The Google Power Meter project aims to provide exactly this level of detail. Smart Metering takes the "exhausting" part out of the effort, while providing the "absolutely necessary" data a consumer needs to make an informed decision.

I think your comment and question is exactly the right one we need to be asking. I'll post an anonymous version of your question and my reply on one of the blogs I post to!

WattzOn Does All the Heavy Lifting for You

And it's worth repeating that if your electricity is from one of the supported vendors, WattzOn can do all of the exhausting dirty-work I did by hand and give you the same view. Just link your account and all the rest is gravy!


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