Trying to locate energy 'waste'

Energy
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Hi, I’ve installed power meters on all my big electricity consumers. For this I use a mix of one Shelly 3EM, a few Shelly PMs, a few Shelly Plug S, and a few Cloudless EU Plugs with Tasmota. I calibrated the Tasmota plugs using a simple old 11w lightbulb.

The odd thing is, even though I’m pretty sure I’ve covered all the large loads, I see a constant 120-170W being used that I cannot account for.

What is not being measured? A few Sonos speakers, ~20 Hue smart bulbs (which are off), and some odds and ends like a few phone chargers. Not things I would expect to consistently pull >100W!

On a daily basis, this adds up to between 2 and 3kW, which is way more than I am comfortable with – without an explanation.

I was wondering if anyone here has seen similar, and if you’ve been able to figure it out? While I calibrated the Tasmota plugs (since the readings were way off at first), I did not do that for the Shelly devices – has anyone seen this being needed?

Any pointers would be appreciated :slight_smile:

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My house pulls around 90-100W in idle state (at night). When almost everything including the fridge compressor is off.

Some devices that pull more power than you might expect or think about are:

  • Ziggo internet cablemodem (I believe 15-20W, not 100% sure).
  • Ziggo Mediabox XL pulls 30-35W both on and off (its never really “off” unless eco mode is selected). If you have one you can have it replaced for free by a newer model (Next or Next Mini) that uses much less energy. And it’s also snappier.
  • WiFi router(s) (5W for my Archer C7).
  • Mechanical ventilation system (100W when on).

P.S. Using an old school light bulb might not be the best way for calibration, as the power it consumes varies with the voltage. And the net voltage is not constant. Also there is probably some variance from bulb to bulb. If its 10 or 12W instead of 11W, that is already almost a 10% error in the calibration.
It would be better to measure the voltage and current using a multimeter, and use that value (Wattage = Voltage x Current) for your calibration.

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Thanks for your response. I’ve got my router and other network stuff measured, so that’s not it. But I had not thought of mechanical ventilation: I have two bathroom fans that are always on at a low speed – I’ll check what they draw!

Also, interesting what you mention about the bulb. I used an old LED bulb, but I imagine that that still doesn’t really matter; voltage still varies. Do you have advice on how to calibrate it more reliably?

Thanks!

4

With LED it might be a little different, since it has an IC that regulates the current.

The best way is to use a multimeter to measure the voltage (V) and the current (A) of the bulb (or any device). And multiply those values to get the power (W).

Disclaimer: However, to measure the current you need to put the multimeter in series with the bulb. And to do that you will probably have to mess around with some wires. And since we are talking about high voltage (230V), it is not without danger of electrocution. So unless you know what you are doing, maybe it would be better to ask someone with experience with these things to assist.
A safer way would be to use a clamp current meter that you just clamp over one of the wires, but I believe they are not as precise. If you use a clamp meter, it’s probably better to measure a high power device, like a 1500 or 2000W kettle, and not a 11W bulb. It will have less error.

5

Coincidently I started to measure energy a few weeks ago. Starting with measuring total energy, then trying to figure out devices that consume the most. And similarly to you, I’m chasing the missing parts of the puzzle :wink:

From my experience, Shellies are pretty accurate. I’m using 3EM for measuring the total consumption of the house. Then PMs, 2.5s, RGBW2s, and Dimmers for separate devices. 3EM is advertised for measurement precision tolerance under 1%. And I can confirm that.

The biggest surprise I experienced recently was a dishwasher. It takes 1.2kWh for 1h 10min shortened ECO program :wink: yeah, I know: the ECO focuses on water consumption, not on electricity.

The second one was a gas boiler. Regardless it’s the gas-powered one, it also drains 1.3kWh per 24h. I know it has an electric pump to circulate water but didn’t expect such a usage. BTW it’s still old-tech “turbo” boiler. Going to replace it next year with condensing one.

Another one was a washing machine which takes about 0.5-0.6W in stand-by :-o.

From other devices: a TV playing a whole day can take more than 1kWh. A fridge is 1.1kWh daily. Network components (3 APs, router, switch, rPi with Home Assistant and SDD) are about 0.5kWh.

Otherwise, there is a number of those forgotten devices always connected to AC like chargers, notebooks, printers, PCs etc. But those drain almost no energy when on standby. But there are also mentioned already electric kettles rated for 2.4W (boiling water takes 3-5 mins), hair fans, vacuum cleaners etc.

Still have to connect an oven. I know it’s rated for 16A. So it may eat even 3.5kWh

with regards

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just measured another consumption on socket with lot of devices in standby.
pc, notebook, korg x5 kayboard, HTC VIVE, small old D-link switch, Prusa Mini +rpi with Octoprint, HP inkjet. All unused/standby.

Total draw makes 40W. After a 24h it will give 0,96 kWh. Without even touching them.

Those numbers are really surprising considering that total of the whole house can be 5.5 kWh. So .25 of total is made by some stand by devices

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Thanks, that’s helpful!
My networking setup incl Hue bridge, Sonos bridge, NAS, HA server, a switch, modem, router, and 2 APs (over PoE) take 1.4kW per day.

But the really big spenders are the electrical floor heating we have. During winter they alone take between 6 and 10kW per day.

I’ve been thinking about separating out the quooker and dishwasher as I’m curious how much of the 2.8kW the quooker is responsible for. We use it for hot water in the kitchen as well as boiling water, which will drive up the consumption.

My gas boiler only takes 0.2kW, but it is a relatively modern (condensing) one.

In any case, I am left with 2-3kW daily that comes from unmeasured devices (or measurement errors on the devices I do measure). This seems like a lot to me, but I just can’t figure out where it is coming from. I think I’ll need to go and switch off all the breakers and turn them back on one by one to see when the consumption spikes more than expected.

Screenshot 2022-12-25 at 12.41.01
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To add to my previous post, this is what ‘live’ consumption looks like right now:

Screenshot 2022-12-25 at 12.47.59
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You cannot just measure voltage and current and multiply them when it is AC unless you have a load which is 100% resistive. Anything LED or anything with motors are heavily reactive with power factor often less than 0.5. You need to use an old incandescent light bulb. Better is to buy a real power meter that can handle and show power factor (cos phi). And then use that with an incandescent bulb to calibrate the smart sockets.

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Thanks, that’s super useful to know. Sounds like I will have to recalibrate the Tasmota sockets then.

I don’t think I have an old incandescent bulb any more though. Are there any other common household appliances that have a resistive load?

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Electric kettle or an electric heater without a fan. Hairdryer or heat gun have fast motor and a significant reactive load. A gluegun is probably also just a heater.

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You might be interested in a thread in which I wanted to do the same: Measure unmeasured energy consumption

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That was my first thought, and it may be quite helpful to do in a carefully orchestrated manner. Another thing you could do is move one of your CTs onto each unmetered circuits one by one a day at time to see where the ‘leakage’ might be. Even doorbell transformers can be a parasitic drain.

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I tried to figure out too where the “baseload” of my house comes from, and I discovered that the electro-thermal actuators of the radiant floor drain quite a lot of energy. Having one actuator for every line, and having something like 15 lines, having the actuators always “open” drains around 60w, permanently (they are always open because I use the climatic curve on the heat pump and some automation to store some heat during the day when I have PV overproduction).
It might be worth a try.

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15

Can you tell me how you make the graphs? I really love how they look.

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Of course, that’s using this component. I find that the Sankey Chart makes it easier to see the remainder compared to the standard energy dashboard’s Individual Devices panel.

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I used an incandescent bulb, a soldering iron, an 1000 watt halogen light and an iron.

I am also looking where my energy waste is coming from and have therefore calibrated my sensors. I still see quite a heavy portion of unaccounted energy. I really cannot think of anything which isn’t measured at this time (I have 24 points on which I measure consumption; 20 with smart plugs and 5 with powercalc integration)

See below a graph of a day in which the entire household was away and most of the appliances were shut off (quooker, washing machine, cv, television, dishwasher, oven, etc)

image
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I found out my induction hob draws 100w when “off”, so I now turn it off at the 45A switch instead when not in use.

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Which eats another 10-20W :wink:

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@maxym , do you mean per plug or if someone has a number of such plugs?