[HN Gopher] Thinking About Smart Home Power Usage
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Thinking About Smart Home Power Usage
Author : niemyjski
Score : 22 points
Date : 2020-02-13 20:33 UTC (2 hours ago)
(HTM) web link (blakeniemyjski.com)
(TXT) w3m dump (blakeniemyjski.com)
| pathartl wrote:
| Are you in the Milwaukee area by chance? Funny that you post this
| today, We Energies just called me today to notify me they were
| installing a new meter for our unit.
| hotswapster wrote:
| I had this scenario too. I purchased PowerTag by a Schneider
| Electric and then tied this into Home Assistant via Node-red.
| This gave me usage on individual circuits and automation resulted
| in a 40% reduction in energy usage.
|
| For curiosity I wired in an SDM eBay brand meter and it was
| within 1% of the Industrial grade PowerTag.
|
| Another option is emonpi and it's easier to install than both of
| the above.
|
| Happy metering! (Oh and you're lucky, Power in Australia is
| $0.28/kWh
| kcmastrpc wrote:
| How do you turn off smart bulbs which require power to retain
| connectivity settings/configuration?
| mikequinlan wrote:
| My Hue smart bulbs retain connectivity and configuration
| settings when powered off (via the light switch). If they
| didn't it would be awful -- you would have to reconnect and
| reconfigure every bulb in the house after each power outage. I
| assume the data is stored in some kind of flash memory.
| filoleg wrote:
| My personal guess would be that the settings are stored
| either on the Hue hub or within the app you use to connect to
| it. Mostly because, I've noticed, after someone turns off my
| Hue bulbs by accident by flipping the switch and then turns
| them on, they don't get restored to the same scene setting as
| they were before. I have to manually change back to the scene
| it was on before being powered off.
|
| On another hand, after reading some articles a while ago that
| mentioned security issues surrounding smart bulbs (when it
| comes to selling them to someone after using them in your own
| home due to some persisted settings), I bet that your theory
| could be correct as well.
| Relys wrote:
| Yeah I hacked around on the Hue REST API a few years back
| and this is how it works.
| inferiorhuman wrote:
| That changed with updated bulb firmware. Initially bulbs
| would reset to their default state on power on, but they're
| now able to save state. The way I read it this behavior is
| not dependent upon the hub or app.
|
| The Phillips app is so junky I just use the hard power
| switches somewhat frequently.
|
| https://huehomelighting.com/new-power-feature-to-retain-
| colo...
| function_seven wrote:
| > _The real shocker was when I decided to measure only the Wemo
| mini smart plug with nothing connected was costing me $0.31
| /day._
|
| I can't buy this. That's 3,100 Wh each day, or roughly 130W
| constant usage. That much energy being dissipated in the plastic
| housing would be burning hot to the touch, or melt it.
|
| I'd wager he's off by a couple orders of magnitude. 1.3W is much
| more likely for a smart plug to draw.
|
| The 55W his Echo is drawing is suspect for the same reason.
| That's more power than almost any idling laptop.
| floatingatoll wrote:
| To calculate the math more correctly, a 1W smart plug is
| contributing $0.09/month to the $400 electrical bill quoted.
| This is a stellar example of a micro-optimization, in
| programming terms.
|
| Focusing on big spenders like "anything with a pump" and
| "anything that generates heat" would contribute significantly
| to reductions.
|
| I once upgraded video cards, reducing my computer's power draw
| by 180W and lowering my electric bill accordingly. This was
| back in the early days of CFLs (they were terrible) so it may
| not seem like much, but it was on 24/7 and that was the power
| at idle. I think it worked out to something like $10/month of
| savings, which was quite noticeable for my total bill of $50 or
| so.
| function_seven wrote:
| > _... and "anything that generates heat" would contribute
| significantly to reductions._
|
| I never measured it, but there was one area that I quickly
| put a Tasmota plug on. My stereo receiver under the TV.
|
| One day I was putting around the den and I noticed a lot of
| heat emanating from the credenza under the TV. It was my Sony
| receiver just sitting there, dutifully amplifying the null
| input from the turned-off TV.
|
| So I added the plug, and told Home Assistant to turn the
| receiver on whenever the TV was on, and turn it off when the
| TV is off. My guess is that I'm saving 20-40W this way. $2-$4
| a month.
|
| (FWIW, this is the first time I've ever been glad to have a
| "smart" TV. The only feature I use on that TV is the ability
| for Home Assistant to see it)
| ip26 wrote:
| 1.5W is cheap to operate, but my god, for the job done that
| seems like a relative power glutton. Entire x86 processors can
| operate, not idle, at 5W.
|
| My favorite story on the subject of relative waste:
|
| https://reductionrevolution.com.au/blogs/news-reviews/584256...
| barbegal wrote:
| Yeah this is likely caused by the poor accuracy of the current
| sensor at very low power and switch mode power supplies can
| mess with the way the data is sampled.
| aequitas wrote:
| In the Netherlands when smart meters where introduced one of the
| requirements was that the meters should have a port with a
| defined standard (DSMR[0]) which could be used by the house
| occupant to read metrics for themselved. The standard is pretty
| well setup with newer versions giving per second power/gas usage
| readings in human parsable ascii over rs232 on an rj11 connector.
|
| [0]
| https://www.netbeheernederland.nl/_upload/Files/Slimme_meter...
| huseyinkeles wrote:
| I have an implementation [0] of DSMR for esp8266 that I
| integrated to home assistant over MQTT.
|
| [0] - https://github.com/WhoSayIn/esp8266_dsmr2mqtt
| Someone wrote:
| I never understood the claim that smart switches on LED
| lightbulbs will conserve energy. The duty cycle of the average
| light bulb is fairly low; I would guess they are switched on for
| <10% of the time, on average.
|
| If so, adding a 'smart switch' that uses 0.5W to a lighting
| fixture that has a 10W LED light bulb increases its average power
| usage by about 50%. You must be fairly sloppy to make that a
| gain, compared to a manually operated switch.
| pdonis wrote:
| _> adding a 'smart switch' that uses 0.5W to a lighting fixture
| that has a 10W LED light bulb increases its average power usage
| by about 50%_
|
| Shouldn't that be 5%, not 50%?
| dwiel wrote:
| they are assuming the 10W is only running 10% of the time and
| the smart switch is running all of the time. That puts the
| average use for the light at 1W and 0.5W for the smart
| switch.
| pdonis wrote:
| Ah, got it, thanks!
| [deleted]
| bcrosby95 wrote:
| Lots of people have gotten lazy about turning off lights since
| LED is so cheap. E.g. I think our kitchen light is on around 12
| hours per day because the switch isn't very convenient. Or the
| garage light - if it's left on during the day, it probably
| won't be noticed until morning.
|
| Also kids tend not to turn lights off.
|
| But yeah, even if you are saving money, smart switches are
| pretty expensive. It will take a while to recuperate the extra
| $ and time invested.
|
| I would focus on switches that control several lights at once.
| E.g. our garage lights use 100 watts in all. Kitchen uses 65.
| Hallway 50.
| barbegal wrote:
| The problem of saving power with small household devices is
| similar to the problem with micro-transactions. The overhead of
| connecting devices into a smart system is far greater than the
| recovered cost in terms of both money and energy. A smart switch
| can easily run to $100 to purchase and install and $10 a year to
| run. So it needs to save you ~$20 a year to be worthwhile. For
| large appliances that are regularly used such as swimming pool
| pumps, air conditioners, scooter or car chargers then it can be
| worthwhile.
|
| I'd like to see smart blinds and curtains become more popular as
| windows can act like a giant highly efficient solar panel heating
| your home up when the conditions are right. Sadly again the cost
| of setting up and maintaining such a system could be ~$100 a year
| so only certain buildings would actually see a return on
| investment.
| [deleted]
| Bedon292 wrote:
| While they may not actually save money over lifetime, its
| possible they do reduce your carbon footprint over their
| lifetime. I am actually curious about that side of things. The
| devices obviously cost some amount of resources and money, does
| their electricity savings every offset their initial creation.
| cushychicken wrote:
| We used to use those Kill-a-Watt probes at work to classify smart
| home device power draw.
|
| Emphasis on "used to". They are not very accurate at all, and the
| sampling interval over which they take data on wall power draw is
| slow enough that you will miss important changes in current draw
| on your DUT. We have since switched over to expensive, calibrated
| Agilent power analyzers with better time resolution.
|
| The post is well intentioned, but I challenge his data collection
| methods. His tools are not up to the task he has set himself to.
| It is not nearly as simple as the folks who sell Kill-a-Watt's
| would have you believe.
| a9h74j wrote:
| A EE video[1] shows such a bad power factor on a mere smoke
| alarm that the VA reading is 20VA for less than 1W actual
| consumption. An unsuspecting "power meter" might overestimate
| actual dissipation.
|
| [1] https://www.youtube.com/watch?v=_kI8ySvNPdQ
| Bedon292 wrote:
| Do you have some of that data available? I think his data does
| seem off, but all these always on devices have to be costing
| something right? Curious what that cost actually is.
| TeMPOraL wrote:
| > _but all these always on devices have to be costing
| something right?_
|
| They probably are; that depends on how badly they're
| designed. But that doesn't mean they _should_.
|
| Consumer devices aren't usually as efficient as they could be
| with some more design work, which I think makes people have a
| wrong reference point about how much power is needed to do
| things. As a counterexample and a way to reset the reference,
| consider e.g.:
|
| - That there exist radio devices that are designed to run for
| _years_ off a single CR2032 battery.
|
| - That there are microcontrollers that can still execute your
| code while drawing nanoamps.
|
| - My 9 m.o. kid has a plush moon with a string attached to
| it; when you pull it, it plays a loud melody (that part is
| mechanical) and flashes LEDs for ~30 seconds. Both are
| powered from the mechanical energy of your pull.
|
| The way I see it, a typical device on standby and/or a
| typical wall wart not charging anything shouldn't pull more
| than some micro- or even nanowatts. So they shouldn't cost
| you more than a hundredth of a cent a month each. Now of
| course they do, there are probably some engineering
| constraints here (like more complicated devices wanting to
| keep RAM powered), and there are definitely business
| constraints (low-power design is more expensive). But to me,
| a device whose standby mode is noticeable on the power bill
| is simply broken.
| cushychicken wrote:
| I don't - it was collected for work, and I'm not allowed to
| share it.
| peckrob wrote:
| My utility also installed smart meters recently - the Focus AXRe
| with Gridstream RF. It theoretically has Zigbee in it. It even
| has the Zigbee logo on it. I haven't figured out if I can read it
| yet, but in fairness I also haven't put a lot of work into
| figuring it out either. At the very least I could not get
| Smartthings to see it. So if anybody knows anything more about
| this meter I would love to know. :)
|
| But I DID discover that my utility, buried down in like 5 menus
| on some random screen of the account portal, offers a usage graph
| at 15 minute intervals. It's not real time - it seems to be
| delayed by 1-3 hours - but it is _far_ better than getting a
| surprise bill. And while it used some weird SAP JSON interface, I
| could deduce what was what and could get the data out of it.
|
| So I whipped up a script to basically scrape this "API" and shove
| the data into InfluxDB. I also added daily scrapes for the
| billing page and the rate page so I know when I was billed and
| how much the current rate is. This is because my utility bills at
| a lower rate for the first 1,400 kwh, and a higher rate for
| everything over that. I was not able to discern any pattern to
| when the bills were issued and the utility company was very
| unhelpful in this regard, just "sometime ever 27 to 35 days
| depending on holidays and weekends."
|
| This [0] is the result of combining all the data. While I would
| really like realtime data directly off the meter, even being
| delayed a few hours is better than a random surprise $370 bill.
| I've written enough scrapers in my life to know it will probably
| break at some point, but it's been humming along nicely for the
| last few months.
|
| [0] https://imgur.com/a/SwdHnCV
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