Resource Monitoring Solution

Electricity, Gas and Water – three resources that are vital in our daily lives. Monitoring them using modern technology helps with conservation, but the real impact comes when we use the available data to reduce wasteful usage over time. [Sébastien] was rather embarrassed when a problem was detected in his boiler only during its annual inspection. Investigations showed that the problem occurred 4 months earlier, resulting in a net loss of more than 450 cubic meters, equivalent to 3750 liters per day (about 25 baths every day!). Being a self professed geek, living in a modern “connected” home, it rankled him to the core. What resulted was S-Energy – an energy resource monitoring solution (translated) that checks on electricity, gas and water consumption using a Raspberry Pi, an Arduino, some other bits of hardware and some smart software.

[Sébastien] wanted a system that would warn of abnormal consumption and encourage his household folks to consume less. His first hurdle was the meters themselves. All three utilities used pretty old technology, and the meters did not have pulse data output that is commonplace in modern metering. He could have replaced the old meters, but that was going to cost him a lot of money. reflective-power-meter-sensorSo he figured out a way to extract data from the existing meters. For the Electricity meter, he thought of using current clamps, but punted that idea considering them to be suited more for instantaneous readings and prone for significant drift when measuring cumulative consumption. Eventually, he hit upon a pretty neat hack. He took a slot type opto coupler, cut it in half, and used it as a retro-reflective sensor that detected the black band on the spinning disk of the old electro-mechanical meter. Each turn of the disk corresponds to 4 Watt-hours. A little computation, and he’s able to deduce Watt-hours and Amps used. The sensor is hooked up to an Arduino Pro-mini which then sends the data via a nRF24L01+ module to the main circuit located inside his house. The electronics are housed in a small enclosure, and the opto-sensor looks just taped to the meter. He has a nice tip on aligning the infra-red opto-sensor – use a camera to check it (a phone camera can work well).

The Water Meter was more difficult. It has a mechanical counter with a set of 8 digits that increment as water is used. His solution was to use the Raspberry-Pi and its associated camera module. The Pi camera is fixed focus to infinity, so he had to adjust the lens to make it in to “macro” mode. And he needed some LED’s for illumination since the meter is in a dark area.

The Gas meter was the easiest since it could be retro-fitted with a pulse counter. The Raspberry-Pi receives the camera pictures, the pulse data from the gas meter (via a LAN cable hack), and a nRF24L01+ module to receive data from the electric meter. He then goes on to describe his “Constellation” software – a project that he hopes to open source soon. There’s some interesting bit about using OpenCV to decode the water meter digits – especially when the digits are in transition. If there is an error in decoding, he receives an email with the relevant snap shot. All this culminates in a nice HTML page that shows the data graphically. He also does a lot of other data processing to generate graphs and tables.

The system keeps him well informed about usage, especially when he moves out of the house. Like the Washing machine turning on, for example. He also did some Audio integration (using another of his software projects called S-Sound), which now announces the amount of water used while showering, for example. This is useful feedback in helping slowly cut down on consumption.

27 thoughts on “Resource Monitoring Solution

    1. No need to limit it to SI units; the units are just plain wrong. Total energy usage should be measured in kWh or MWh (or MJ or GJ if you want to stick to SI units), not kW (which measures power, not energy). And W/h is a thoroughly useless measurement of the “acceleration” of energy usage, since the rate of change of power draw rarely follows a linear, or even particularly smooth curve.

      1. Hello Ben,
        Yes it is true the total consumption of electricity given by my meter is “kWh”. I just forgot “h” in the HTML template in this page;)
        However gauge in Wh gives a good estimate of the instantaneous consumption given the disk revolution time. Much more reliable than amperometric clamp.

        1. Wh (in your comment) and W/h (in the screenshot) are not the same unit. Neither of these units describe instantaneous consumption. The watt is the SI derived unit for power (instantaneous energy consumption) which is defined as 1 joule (the SI base unit for energy) per second (the SI base unit for time). Therefore, 1 Wh = 1*60*60 J*s/s = 3600 joules of energy (i.e. total consumption). 1 W/h = 1/(60*60) W/s = 1/3600 J/s^2 (i.e. rate of change of the rate of energy consumption; not practically useful)

          The reason current clamps are less accurate for measuring power consumption is because they only tell half the story – they must be paired with a voltage measurement and both must be sampled at a high rate to accurately measure RMS power, but this type of measurement has the advantage of also being able to measure power factor, frequency, wave shape, etc.

  1. Quite an extensive system. A much simpler solution to the water meter would be to remove the clear face plate, then put a piece of black tape over one of the njmbers on the least significant digits. Then detect it just like with the electrical meter.

        1. And what if the problem happens between your meter and the official one? Blissfully unaware until it costs you a fortune in your next bill is it…
          Far fetched? I actually had this scenario when the provided meter in a french property leaked from a line in the glass of the meter itself which once it went away for analysis, the water company said it was down to frost damage and not being sufficiently protected from the winter cold, I actually had to pay for the lost water. The tennant never thought to actually see what her consumption was until she was moving out despite the soggy garden near the meter chest.
          By the time I got stung for this and a bunch of other things it actually cost me for the privilege of having someone live in my property there. House has sat empty for four years since waiting for property prices to recover before its sold.
          Way to go solving housing issues France.

          1. Dave, tl;dr indeed, me and my family lived in a mobile home while i was building its replacement myself 2km up the road (where Im typing this from the office of now) and the house rental idea was supposed to finance the materials. Come back and whine about over privileged people and vacation homes when you have had to break the ice off the toilet bowl to take a dump in the morning then get up and do a days graft after buildng a fire under a machines diesel tank to get it to thaw.
            Yes I am now privileged to be where I am now, but its as a result of my own hard work & nobody handed me anything and Im the youngest offspring of a single parent family.

            I suggest taking a look at your own life, and seeing how you can improve your own situations rather than taking the easy route of any issues by trying to whine about differentials on percevied backgrounds.

            tl;dr; Your a dick.

  2. I’m using this solution on my electromagnetical induction watt-hour meter for months (but with photo resistor instead of photo-diode), and it’s very reliable I have to say :) Nevertheless, I divide the energy of one rotation (10 Wh in my case) by the time it takes to make the rotation to have the power in Watts…

  3. Heads up – Don’t use an iPhone camera as they filter IR. I have always used camera phones to check IR Emitters and remote controls are working and one day whilst fixing a TV remote I threw a couple of IR emitters away because I could see no flashing on my new iPhone. DOH!

  4. So, does anyone here see how this could be a positive for the anti-SMART meter movement? The argument used by utilities for pushing SMART meters is that they need real-time or near real-time usage data from customers and that its cost prohibitive to have a human being continually check the analog meters of their customers. The SMART meter will give the utility direct access to usage data however it also gives the utility direct (remote) control over the customers power and direct access to any smart enabled devices the customer may have that works with the SMART Meter/Grid. The device this Sebastian has come up with would enable analog meter customers to get this data and (via the internet) send it to the utility without giving the utility direct control over their usage.

    Whether you believe that the SMART Meter is a good thing or not there’s no denying its invasive or that its setting a precedent for forcing people to accept something they don’t want under the guise of being for “the greater good” or “for the planet”. If it’s OK to force an American citizen to accept a smart meter then what else will be OK to force on people for some cause? The myth of the earth being over populated by humans has been thoroughly debunked but before it was successfully debunked there were efforts to push for population control under the guise of “protecting the planet”.

    1. but SMART meters will detect outages and dispatch techs ASAP. It also enables electric companies to charge consumer more during peak hours which is what I think what the big deal about SMART meters.

      Nobody cares what appliances you use in your home, they just want more $$ out of you, considering so many devices are energy efficient, electric companies need to switch up their game.

      1. And $$$ for manufacturing and installing smart meters.
        Smart meters are networked computers, so they will have to be replaced much more frequently than conventional meters
        (for security, to fix errors, obsolete, etc.)

        Conventional meters last for several decades, smart meters – optimistic projections bit over 1 decade.
        Planned obsolescence. Now how green is that?

  5. Unfortunately with my utility (Westar) they don’t allow anything to be attached to or blocking the meter. I had used a laser pointer diode and photo-resister in a tube taken from a mechanical pencil (to reduce ambient light detection) in a sealed enclosure for a project just like this. I ended up zip-tying it to the side of the housing so it could read the disc, but not obscure the face.

    Ultimately it ran about a month (with reasonably good success; sans cloudy days) before the meter man came by and removed it for me; leaving a polite note about their policy.

    I did find that running the furnace blower, a/c and clothes dryer were by far the largest consumers of electricity. The blower taking about 1200 watts, a/c around 2000 and the dryer around 2500. The fridge came in second place at about 400 watts and entertainment center at 200-300. The most surprising thing was that baseline usage never dipped below 120 watts; mostly thanks to the two satellite receivers that had a lousy sleep mode.

      1. Which isn’t rated for 220 volts (the clothes dryer and A/C) nor could come close to handling the wattage of the larger consumers. I have one, it’s nifty as hell, but it only covers maybe 20% of my usage.

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