[HN Gopher] Smart thermostats inadvertently strain electric powe...
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Smart thermostats inadvertently strain electric power grids
Author : PaulHoule
Score : 97 points
Date : 2022-07-14 13:21 UTC (9 hours ago)
(HTM) web link (news.cornell.edu)
(TXT) w3m dump (news.cornell.edu)
| bob1029 wrote:
| The power grid is a very complex thing, and I strongly believe
| that demand management is an important component for stability.
| There are ways we could better organize our HVAC fleets to
| provide near-equivalent levels of comfort. The current proposals
| really suck though.
|
| Storage is a big deal that seems to be the focal point of most of
| the renewable/non-renewable debate, but there are other concerns
| that are discussed less frequently.
|
| Having sufficient inertia in the grid is important as well. It's
| like a low-pass filter for the desired grid frequency. The less
| equivalent spinning mass you have, the easier it is for these
| spikes to cause serious problems - Even if you have a gigantic
| reservoir of water ready to spin up some turbines, you still need
| to be able to handle all of the instantaneous events up to that
| point, during, and following.
| mikepurvis wrote:
| I guess I don't know what's out there, but it feels like there
| must be a bunch of industrial-type loads that could be pretty
| flexible, and would absolutely benefit from a model where they
| get electricity for a fraction of the price with the promise
| that the utility can throttle them back by 80-90% at a second's
| notice.
|
| Think stuff that's naturally storage-oriented, like charging
| forklift/AGV batteries, pumping something into a tank, boiling
| a large kettle, etc. These are all potentially loads where the
| convenience cost might be well worth a discount from the
| utility, where the discount is maybe proportional to how long
| the throttling can be-- some loads you'd only want to lose a
| few minutes (so, basically buying the utility time to spin up
| another turbine), whereas others you could lose for hours at a
| time (actual load shifting).
| mistrial9 wrote:
| what I am reading here is that the first use-case for "smart"
| remote is .. remote service disconnect. Profit goes Up. Second
| use-case is better dossier building. "smart"
| wongarsu wrote:
| I wouldn't be surprised if "power plants" that just provide
| inertia pop up. Basically flywheel storage, but with the intent
| to keep the flywheel at a fixed saturation level to stabilize
| the grid frequency.
|
| But we are at an interesting point in time where "smarter"
| devices make the addition of demand management easier than
| ever, and at the same time less predictable power generation
| makes demand management financially more attractive. We just
| have to settle on the right mechanism: do electricity prices
| stay simple, but the provider can control your devices, or are
| electricity prices reflective of actual supply and devices
| regulate themselves based off that.
| russfink wrote:
| Set your timer based on the last two digits of your house or
| apartment number. If everyone did this, ... ?
| photochemsyn wrote:
| Smart thermostats could really be a lot smarter, in particular if
| you had a little bit of local battery storage, but even without
| that it's possible to imagine a thermostat that could be set to
| lower electric bills based on real-time monitoring of electrical
| prices.
|
| > "With few exceptions, when the load peaks, the price also
| peaks. So, if you can move some of your electricity consumption
| away from the peak times, real-time pricing will enable you to
| save money by buying more of your energy at lower prices."
|
| There are many ways to implement this but it might result in a
| fairly pricey thermostat requiring an internet connection and the
| ability to automatically switch from grid power to local battery
| power as prices fluctuate. It would likely reduce demand
| variation however.
|
| https://extension.psu.edu/real-time-pricing-for-electricity
|
| Some people have also rolled out notions like allowing utilities
| to control thermostats remotely but I think that'd be very
| unpopular for most people, it has too many dystopian Big Brother
| connotations.
| LeifCarrotson wrote:
| Every house is already a battery, with significant thermal
| mass. Unfortunately, this means that the is not real-time but
| forward-looking: The thermostat needs to predict when load and
| price will peak a few hours early, and turn the AC on before
| that happens. If you cool the house down lower than necessary
| in the morning, it will warm up through a high-load afternoon,
| but stay comfortable, spreading the load and reducing usage
| during that price peak.
|
| Of course, if everyone does this on every morning when the
| national weather service predicts high temperatures, you've
| just moved the demand forward a few hours and not actually
| spread it out.
| praptak wrote:
| Inadvertent mass synchronization is a known pattern and it has a
| solution: jitter everything, even things triggered by events
| which you don't think about as synchronized.
|
| Your widget needs to fetch data periodically and the network
| connectivity died. You'd be tempted to start fetching data right
| away after it goes back, right? Okay, but if a huge network
| provider gets back from an outage, you will have a problem - all
| widgets in that region will start fetching data at the same
| moment.
| krallja wrote:
| This is why one of the goals of the "smart grid" is demand
| response: the loads and grid need to be able to react to each
| other.
| CoffeeOnWrite wrote:
| Just curious, is there a term more inclusive than demand
| response that accounts for generation-side factors like weather
| and fuel economics/logistics?
| konschubert wrote:
| Considering how widely the price of electricity varies throughout
| the day, we urgently need to translate this into end consumer
| pricing in order to better shape demand.
|
| https://energy-charts.info/charts/price_spot_market/chart.ht...
|
| This doesn't mean that end consumers should pay spot prices - we
| have seen where that leads in Texas. But having four distinct
| prices for night, morning, day and evening might already achieve
| a lot.
| joezydeco wrote:
| We've had real-time pricing in our area (ComEd/PJM) for over a
| decade now, and we even have celluar+Zigbee-enabled smart meters
| attached to all the homes. I even bought a gateway where I can
| read my usage with pretty good resolution every 10 seconds.
|
| But, still, none of the large thermostat makers offer any type of
| integration to the local utility. Or even the local weather!
| ComEd actually offers a box with a 3G modem that sits outside
| next to the A/C compressor and will cycle it off when demand is
| too high. But even that has no connection to the inside system.
|
| Ecobee. Nest. Honeywell. Johnson. What's up with everyone?
| ceejayoz wrote:
| My utility can (with an opt-in on my part) tell my Nest to go
| into power-saving mode on a high demand day.
|
| https://support.google.com/googlenest/answer/9244031
| pfdietz wrote:
| This is reactive; a better scheme is proactive: on a day when
| the A/C demand is likely to be high, precool the house during
| off hours to 60 F and then turn off the A/C.
|
| Simply exposing homeowners to real time pricing would be
| useful, even if nothing is done automatically with that
| information.
| ceejayoz wrote:
| Nest's does exactly that; there's a pre-cool phase.
|
| https://support.google.com/googlenest/answer/9749812
|
| > Once your thermostat knows the Rush Hour is coming, it
| may pre-adjust the temperature in your home before it
| starts. This is so less energy is needed to heat or cool
| your home during the Rush Hour event.
| taylodl wrote:
| I really don't like the strategy of super cooling in the morning.
| I prefer fresh air instead. I throw the windows open wide and let
| all the cool morning air in. By midmorning I'm usually starting
| to close those windows because the outside air is getting warmer.
| By mid afternoon I'm closing all those windows and turning on the
| AC and setting the temperature to 1 degree (Fahrenheit) cooler
| than the current room temperature. I've found that temperature is
| in the range of 78-84 degrees depending on humidity. Then the AC
| kicks on and removes all the humidity and makes things
| comfortable. In the evening when it starts cooling back down
| again I turn off the AC and open the windows back up.
|
| I'm paying 50% less in cooling costs than those cooling an
| equivalent space as mine and I'm getting plenty of fresh air and
| I'm still working comfortably. Heck, today is one of those days
| where the highs are going to be in the low 80's and I probably
| won't even need to turn on my AC. In fact it's already at the
| high for today, 84, and it's 76 inside my house and I have a nice
| breeze coming through the window.
|
| Just another way how working from home is saving me money and
| improving the environment.
| codazoda wrote:
| I don't want to pay for them but I do wish I had automatic
| windows. It would be so nice if my windows automatically opened
| if the temperature outside was a few degree's cooler than my
| house and I was in "cool" mode. If it took the wind into
| consideration, even better. My house cools off so nicely when I
| open windows on opposite sides, but I have to remember to open
| and close them at the appropriate times and I have to be around
| to do it.
| googlryas wrote:
| Automatic windows seem hard, but you can accomplish this
| "easier"(not super easy, but doable if you are a home DIYer)
| by having a "whole house fan" + a make up air unit(basically
| a vent that opens up when the fan turns on, supplying outside
| air to replace the air the house fan takes away).
|
| Fairly common to see here in Boulder and the front range in
| older homes(before ubiquitous AC units), because it tends to
| be cool at night + hot in the day during summers, so around
| 5AM you can have the house fan turn on, cool your house, and
| then you ride that throughout the day until the evening when
| the temperature starts to drop again. Works quite well IMHO -
| my first rental had a system like this as well as AC, but I
| actually never touched the AC.
| asdff wrote:
| This is why houses had awnings 100 years ago. You could leave
| the window open and not worry if it rained.
| corrral wrote:
| They also had a bunch of other adaptations for better
| Summer airflow. Large, open attics with multiple windows or
| vents, open to the lower floors (no doors in the way), to
| help hot air go up and out; high ceilings (an aid, not a
| hindrance, to cooling, if you're not using AC); floor plans
| and house placement that took prevailing winds into
| account; larger windows for better airflow when they're
| open, and usually on _all_ sides of a house, roughly
| symmetrically (look at modern houses, lots of them have at
| least one side with no windows); big, straight, end-to-end
| hallways to let air blow through; and so on.
|
| AC cooling efficiency requires abandoning several of these,
| and others are simply not given much thought because they
| don't matter if you're using AC all the time anyway. Which
| is unfortunate, because it shrinks the parts of the year in
| which going AC-free with windows open is viable.
| Rayhem wrote:
| Adaptive vents, too. Why cool the whole house when I'm going
| to be in two rooms for the majority of the (hot) afternoon
| before opening the window to the bedroom in the evening?
| corrral wrote:
| That's essentially what zoning is, most commonly used to
| heat/cool different floors of a house separately without
| having to have multiple furnaces and AC units. If I
| understand correctly, you want the shut-off flaps or gates
| as close to the blower as possible for maximum efficiency--
| just shutting off the vents at the ends of the lines would
| mess with pressure and airflow in the rest of the system in
| undesirable ways.
| moistly wrote:
| I want floor vents that are wireless networked, coupled
| with occupancy, CO2, and temperature detectors. They should
| have the smarts to figure out when to open and close, such
| that rooms are never stuffy, and never too hot or cold.
| bombcar wrote:
| If you setup water heater / cooled systems using the in-
| floor (sometimes in-wall) pipes, they get that almost for
| "free" - you can turn on and off zones very easily.
| moistly wrote:
| That's a fine idea when building a new house, but
| untenable for a house that is not being thoroughly
| renovated. My forced-air HVAC system is built-in, and
| replacing the register vents would run me under $2K at
| $100 a pop. Ripping up my flooring and installing in-
| floor heating would cost me tens upon tens of thousands
| of dollars.
| conductr wrote:
| I have a similar lows in the 80s. Except high is 105. I also
| have a wife that likes it 65 (70 is our great compromise). I
| don't think any of this precooling/ventilation hacks would work
| for me. This time of year, even at night (thermal mass), if my
| AC turns off the house temp goes up about 1F every 5-10
| minutes. It's just brutal.
| LazyMans wrote:
| I predict in certain areas, "free cooling" systems will become
| the standard. These are system which do just what you talk
| about automatically. When there is a need for cooling and
| exterior air is cool enough, supplement supply air with air
| from the outside. This way your AC system load is reduced, or
| if cool enough, the compressor doesn't need to run at all to
| remove heat from your home by replacing it with cooler air from
| outside.
|
| Free cooling is already part of many commercial AC systems,
| usually referred to as an "economizer".
| giarc wrote:
| I wish I had a system like that and have thought about it a
| lot. I live in Calgary and today will be 28C and it will go
| down to 12C at night. I wish my system could just run a fan
| at 7am and draw in a ton of cool air to cool the house.
| Instead my AC runs for 30 minutes or whatever. Seems like a
| waste.
| gedy wrote:
| I'm working towards that with my Home Assistant
| installation, using inside and outside thermometers. You
| can trigger the fan based on the appropriate parameters,
| time of day, temps, etc.
| dimal wrote:
| I've been wondering why my Nest thermostat doesn't already
| have an option to do this. I can turn on the fan manually,
| but it's not smart enough to do that automatically when it's
| cooler outside than it is inside.
| 6d6b73 wrote:
| If the grid can't deal with thes thermostats turning on heating
| in many homes at the same time, how will it function when we add
| millions of electric cars to it?
| ars wrote:
| I had a Smart thermostat for a while, but removed it because it
| was costing me extra energy.
|
| My boiler is more efficient if it runs at low. But with the
| thermostat allowing the house too cool off, the boiler had to run
| at high to warm up the house in time. (I don't remember the exact
| number it's something like 98% vs 80% efficient.)
|
| This ended up using more energy, than leaving it to run at the
| lowest possible output temperature the entire day.
|
| When I googled this I found that Energy Star does not consider
| smart thermostats to be energy saving.
|
| I suspect the same will be true of A/C - letting the heat pump
| run at very low all day will save more energy than high speed to
| quickly cool the house.
| labrador wrote:
| It's a well known problem, so I'm surprised no one thought about
| it ahead of time
|
| https://en.wikipedia.org/wiki/TV_pickup
| cratermoon wrote:
| There's also the semi-mythical "Super Bowl Flush"
| https://news.arizona.edu/story/super-bowls-super-flush-just-...
| lotsofpulp wrote:
| Perhaps we should have a national "if it is yellow, let it
| mellow, if it is brown, flush it down" ad campaign.
| ceejayoz wrote:
| Australia has split flush buttons, with a half-size flush
| possible. Haven't seen many here in the States; might be
| good to require in new construction.
| hyperman1 wrote:
| I've found a toilet requiring 4 or 5 flushes before
| things move. Otherwise they just go merilly around in
| circles. It has 2 buttons, and a message to push the
| right button and save the planet.
|
| If there exists a hell for toilets, that one belongs down
| there.
| ceejayoz wrote:
| That's another thing Australia one-ups us on; the toilets
| are _vigorous_.
|
| None of this slow swirly watch it spin away shit; it's
| more like an airplane toilet in aggressiveness.
| mrguyorama wrote:
| You can buy toilets and toilet "tanks" that are
| pressurized. They are incredible and probably can use
| less water.
| Jaruzel wrote:
| UK has those too (is there a European directive for
| them?)
|
| In almost all cases they are shoddily built and break
| really easily. I miss a proper metal lever based flush.
| lotsofpulp wrote:
| They exist, but in my experience are unnecessary. Just
| adds another component that can break, and saves less
| water than simply not flushing.
| [deleted]
| KoftaBob wrote:
| Yeah very very few people are going to follow that, the
| vast majority will find the idea disgusting and not nearly
| beneficial enough to justify it.
| lotsofpulp wrote:
| Hence the educational ad campaign to inform and inspire
| change. It is just for the home anyway, not public
| restrooms.
|
| And at the end of the day, even if the vast majority find
| it disgusting, increasing water/sewage prices will force
| the change sooner or later.
| collegeburner wrote:
| that is so patronizing. you can't "educate" when people
| find something disgusting and saying that's "educating"
| is arrogant. like if that's objectively people's
| preferences you can't say your preference is right and
| therefore you're "educating" them. and there's good
| reason, it still smells. so no imma keep flushing it.
| lotsofpulp wrote:
| Obviously if it smells, you should flush. But in my
| experience, my urine in the toilet bowl never smells
| outside of when I eat asparagus. Perhaps it is a sign to
| drink more water?
|
| The education is also about water not being an unlimited
| resource. I have no idea how educating or reminding
| people of that is patronizing or arrogant, but to each
| their own.
| hyperpape wrote:
| It does seem like there are a few details that are different,
| because the thermostats will put sustained load on the grid,
| whereas the TV pickup will not. That means that a couple of
| nice technical solutions like adding jitter to the startup
| times would solve the pickup problem, but not the increased
| load at 6:00 AM.
| yencabulator wrote:
| > adding jitter to the startup times would solve the pickup
| problem
|
| There's minimal jitter in people's behavior when they are
| explicitly synchronized by a television broadcast, and none
| can be added within the constraints of broadcast television.
| hyperpape wrote:
| Of course. I was referring to adding jitter to people's
| thermostats, which is not a bad idea, but would not solve
| the entire problem here.
| kevincox wrote:
| How is this different from a regular timer thermostat which turns
| on exactly at the set time?
| cyril_st_john wrote:
| The article suggests the difference is that smart thermostats
| have the timer feature enabled and configured the same by
| default, and most users do not change the defaults.
|
| Even if most other thermostats have a timer feature, I guess
| they are not all turned on and set to the same time by default.
| bob1029 wrote:
| I believe the smart thermostats are all synchronized with NTP
| servers and are able to much more precisely coordinate their
| activities as a side-effect.
|
| Non-smart thermostats (even digital ones) usually drift on the
| clock settings substantially over time.
| loeg wrote:
| It isn't. The dumb timer thermostat my parents had in the 90s
| would, if widely installed, cause the exact same synchronized
| load problem.
| [deleted]
| cshokie wrote:
| Syncing the time over the internet would make them a lot more
| consistent.
|
| Our non-smart thermostat has trouble keeping accurate time and
| drifts a minute per month or so. That would spread the load out
| more because "6am" is a ten minute window.
| furyg3 wrote:
| This doesn't make any sense, though, as nobody turns on a
| heater for 10 minutes. Even if there is drift of 10-15 mins,
| there would still be a peak usage at 6:15 when all of the 6AM
| 'starters' are sucking power from the grid.
| michaelt wrote:
| Imagine a grid supplied by a single coal-fired power plant.
| When demand rises the voltage drops and the frequency
| reduces, and the power plant has to start adding coal to
| the fire faster to get the voltage and frequency back to
| normal.
|
| If the demand rises over the course of 10 minutes, you get
| a small drop in voltage and the plant ramps up gradually.
|
| If the demand rises by the same amount over the course of 3
| seconds, you'll get a much bigger voltage drop and the
| power plant has much less time to speed things up.
|
| There's further complexity because real power grids are the
| size of nations and have many power plants. If several
| power plants notice the voltage dropping and increase their
| production, a few seconds later you might have too much
| power. Then they might respond by cutting their production,
| and a few seconds later you have too little power and so
| on.
| naasking wrote:
| > If the demand rises by the same amount over the course
| of 3 seconds, you'll get a much bigger voltage drop and
| the power plant has much less time to speed things up.
|
| More than that, if the voltage drops too low, like from a
| sudden large power draw, you could get a brownout or even
| a blackout in severe cases. Voltage level is monitored
| and wild swings indicate instability which trips various
| safety systems.
| delecti wrote:
| I think thermostats "smarter" than a simple bimetallic strip
| were relatively rare before modern internet connected
| thermostats.
| InitialLastName wrote:
| Until recently, most of the thermostats I've seen in newish
| buildings (in US northeast) since I've been aware of
| thermostats (1995?) have been digital with clocks and timers.
|
| Older buildings have had the electromechanical thermostats
| you describe.
| spogbiper wrote:
| every apartment i've rented in the last 20 years has had a
| thermostat with some kind of clock and program capability.
| never used any of it, but I don't think they are rare
| delecti wrote:
| Interesting, mind if I ask where you are? None of the ~6
| apartments I've rented had anything beyond a temperature
| setpoint.
| pjz wrote:
| Other things (besides time & current inside temp) that a
| thermostat could (should?) use: sunrise/sunset time, hourly
| weather forecast, current & projected house power usage, current
| & projected grid power usage
|
| Note that almost all of those inputs are going to be identical
| for people in the same area, so as others mentioned building in
| some jitter is necessary.
| yellow_lead wrote:
| Smart thermometer manufacturers could solve this fairly easily by
| randomizing the start time. Instead of them all turning on the
| heater in the winter at 6am, they could i.e pick a random start
| time between 5:30-6:30 by default.
| pdonis wrote:
| That just means the load peak is now at 6:30, when all the
| heaters are turned on.
| yellow_lead wrote:
| It would be a smaller usage at 6:30, and not necessarily a
| peak, since usage would probably surpass it right after
| pdonis wrote:
| _> It would be a smaller usage at 6:30_
|
| Why? Won't all the heaters that turned on from 5:30 through
| 6:30 be on?
| naasking wrote:
| Even if they're all on by 6:30, that gives the power
| plant time to ramp up production to meet demand from
| 5:30-6:30.
|
| If everything is synchronized and everyone in a region
| starts drawing lots of power at the exact same time, the
| line voltage on the grid will suddenly drop below safety
| thresholds and could trigger a brownout for that whole
| region. The point being, randomizing power draw over a
| period of time allows the grid more time to match demand.
| pdonis wrote:
| _> that gives the power plant time to ramp up production
| to meet demand_
|
| But the capacity isn't there, at least not if the
| article's primary claim is correct:
|
| "the peak demands are concentrated primarily when
| renewable energy is unavailable"
|
| It doesn't seem like the availability of renewable energy
| will be much better at 6:30 vs. 5:30 or 6:00. So once all
| the demand is ramped up, there would still be a capacity
| shortfall.
| naasking wrote:
| I'm saying that even if the power were there, these smart
| thermostats would still strain the grid by turning on all
| at exactly the same time.
|
| Power coming from renewables can exacerbate the problem,
| thus requiring grid storage, but the problem remains even
| without them.
| SketchySeaBeast wrote:
| This might be a regional variation for how people are
| imagining this - I agree with you, living in a cold
| environment my furnace takes 2-3 hours to get the house
| up to temp, even longer in extreme (-30) cold, and will
| still have prolonged on/off cycles after the house heats
| up so that it's pretty much guaranteed to still be
| running in case of a staggered start. Warmer climates
| might be able to get things heated up in less than that
| hour.
| mikepurvis wrote:
| Cron has a bunch of this kind of thing built in for stuff
| that's known to touch the network, like automatically running
| apt-update in the background. You don't want millions of Ubuntu
| machines in each timezone all hitting the CDN within seconds of
| each other.
|
| I think Google Maps does it too with routing-- it adds a bit of
| fuzz so that it doesn't send literally every car down path A
| when there's a path B that's nearly as goo.
| ciupicri wrote:
| systemd.timer [1] also has AccuracySec, RandomizedDelaySec
| and FixedRandomDelay.
|
| [1]: https://www.freedesktop.org/software/systemd/man/systemd
| .tim...
| namecheapTA wrote:
| Commercial properties almost all have white roofs. Homes almost
| all have dark roofs. I wish someone would do the math on how much
| heat we're capturing into our houses because we want them to look
| nice.
| panarky wrote:
| The issue described is wrongly attributed to smart thermostats
| like Nest and Ecobee.
|
| It's about any dumb thermostat that runs a schedule, so that HVAC
| kicks in at, say, 6:00 am for thousands of homes and businesses
| simultaneously.
| sjburt wrote:
| Seems like less of a problem for smart thermostats (which will
| likely adjust to an odd-number start time based on your actual
| patterns and the heating speed of your house) versus the clock-
| based thermostats where everyone just had set it to 6am because
| that was the default and it was a pain in the ass to change it.
| toomuchtodo wrote:
| Related discussion yesterday:
| https://news.ycombinator.com/item?id=32088558
| furyg3 wrote:
| Isn't this the same if you have a 'dumb' thermostat set on a
| schedule, which is presumably what most people have anyways? Even
| if you have a 'really dumb' thermostat, presumably people are
| waking up at similar times and turning on their heaters...
|
| I sometimes wonder if the smartest thermostat isn't actually a
| 'really dumb' thermostat on a timer. As in, you want it to be
| warm? You have to get up and set the heater to 21C/70F, this
| turns off after 4 hours (or when you lower it). This way if
| someone hit snooze, their 'smart' thermostat isn't turning on the
| heater at 6AM. If they usually are home at 7PM but have dinner at
| a neighbors house, it doesn't think they are commuting home and
| start turning on the AC...
| bcbrown wrote:
| That's essentially the system I use. I have it set to turn the
| furnace on for an hour in the morning right before I wake up.
| Other than that, I manually set the temperature when I'm at
| home over the course of the day. It automatically resets at
| noon, 4pm, and 11pm back to 63 degrees, so if I don't turn it
| off before leaving, it'll still reset pretty soon.
| tbihl wrote:
| If your goal is to frustrate the user and confound planning in
| the name of saving some energy, my understanding is that that's
| the core feature set of Nest once you pair it to your utility.
| evanreichard wrote:
| Ecobee has eco+ which has "Community Energy Savings" [0]. It was
| just way too intrusive. It seemed to be a reactive system vs
| proactive. Technology Connections goes into this more [1], but I
| believe they should be providing a system that proactively cools
| when there is less demand _prior_ to an expected increase in
| demand. Effectively using your house as a "battery".
|
| When I had it enabled, I was _always_ too hot (in the summer)
| during peak hours. Sorry, not sorry: I'm not willing to sacrifice
| my comfort for the ~$10/mo incentive.
|
| ___
|
| [0] https://www.ecobee.com/en-us/eco-plus/community-energy-
| savin...
|
| [1] https://www.youtube.com/watch?v=0f9GpMWdvWI
| tguvot wrote:
| in reality it's hard (and probably expensive) to proactively
| cool house with AC during summer at hot/sunny regions. I live
| in a house with rather good insulation (the one mandated by
| code) in south bay, yet all the walls getting rather warm and
| even if you try to precool air with AC walls with bring
| temperature back quickly
|
| My solution was to install whole house fan which runs through
| the night when temperature drops to 16C-14C. It allows to both
| replace air with colder one multiple times and due to improved
| air-flow to cool off the walls.
|
| After I shut windows close at morning most of the houses stays
| within comfort zone ( < 22C) till 6-7pm even on 40C days
| mrguyorama wrote:
| If you can feel that your walls are warm I don't think that's
| good enough insulation.
|
| The whole house fan solution is great though.
| tguvot wrote:
| i have walls insulated according to california build code.
| it's not really possible to add more insulation to them,
| unless you rip them off and do spray in insulation.
| insulated attic with radiant barrier and insulated floors.
| i just checked with IR camera, most of surfaces in the
| house are now 22C-24C. After a few days of 40+C walls ill
| go to 25-26. some walls (south side of house) even higher.
| There are few little spots where insulation doesn't sit
| properly - it will be around 28C. The biggest offender is
| skylight. Temperature near top of it can get to 60C.
|
| Edit. I think most people simply do not realize what
| temperature have internal and external walls in houses and
| how it interacts (or counteracts) AC. If you will go to
| read greenbuildings/passive houses forums, there are a
| bunch of discussions about thermal mass of the walls
| reaperducer wrote:
| _it 's not really possible to add more insulation to
| them, unless you rip them off and do spray in
| insulation._
|
| Actually, it's possible to inject foam insulation into
| walls without ripping them off. It goes in through small
| holes, or through utility boxes. Plenty of companies do
| that. I've even seen it advertised on TV in California.
| tguvot wrote:
| I know.
|
| But injectable foam insulation usually going into empty
| walls. I already have butted fiberglass in there. I don't
| think it's viable to make laparoscopic wall surgery to
| remove fiberglass . I did a quick google, and looks like
| you can do injectable foam over fiberglass. But I am not
| sure how much R it will add, but I am sure that for cost
| of of injectable foam + wall repair, I can get another
| hvac and run it for next 10 years...
|
| I did consider recently to double walls on sunny side of
| the house with few layers of foil backed foam boards.
| mrguyorama wrote:
| Do you have any actual numbers for what is up to code
| insulation in California? California is a very temperate
| climate. I wouldn't exactly expect their code to have the
| highest insulation requirements.
|
| Also, building codes should be considered the minimum.
|
| I am keenly aware of how much thermal mass walls hold. My
| apartment is 3 external walls that are constructed pretty
| much only of a few inches of concrete, bare. The result
| is that after a full day of summer sun, even though it
| drops to 64 degrees outside at night, my air conditioner
| cannot keep it 76 degrees or lower inside. It's crazy.
| It's worse in the winter when I can feel the walls
| sucking heat out of my apartment.
| tguvot wrote:
| >Do you have any actual numbers for what is up to code
| insulation in California? California is a very temperate
| climate. I wouldn't exactly expect their code to have the
| highest insulation requirements.
|
| R-15 for 2x4 or R-21 for 2x6. Not highest numbers in USA
| I guess and after you buy house that already "exists",
| it's expensive to change it.
|
| >I am keenly aware of how much thermal mass walls hold.
| My apartment is 3 external walls that are constructed
| pretty much only of a few inches of concrete, bare. The
| result is that after a full day of summer sun, even
| though it drops to 64 degrees outside at night, my air
| conditioner cannot keep it 76 degrees or lower inside.
| It's crazy. It's worse in the winter when I can feel the
| walls sucking heat out of my apartment.
|
| Whole house fan is the way to go. If you can't install
| one, I think a couple of strategically placed window fans
| over night to create some air flow through the house
| might work better than AC
|
| I did some research on preventing walls from getting too
| hot (my room wall on the outside hits 170F i think).
| Narrowed it to
|
| - Transparent paint with some particles that reflect
| sun/reduce heat gain
|
| - Awning
|
| - Shade sail
|
| - Trellis and grow some vine to cover the wall.
| bluGill wrote:
| 2x4 walls are allowed at all? That surprises me, up in
| the north they haven't been legal for decades now. Well
| it is more you can't meet the rvalue with them, but still
| even cheap houses don't get them
| tguvot wrote:
| no idea. Insulation levels are part of the code. It will
| be used at least for cases "deep remodels" when house is
| stripped down to skeleton
| mulmen wrote:
| > my room wall on the outside hits 170F i think
|
| That seems unbelievable! Is that a typo?
| tguvot wrote:
| Nope. It's west facing stucco wall without shadow. It's
| on sun through most of the day. With IR camera i clocked
| it in range of 65C-75C multiple times (so it's maybe not
| 170, but 165. hate C<>F conversions in head) . I had
| inverter on this wall, and it simply died from
| overheating. Same wall on the inside get's to 30C or more
| if I don't run AC that blows on it. Wall is triple layer
| stucco over plywood, R13 fiberglass and then drywall.
| mulmen wrote:
| That's amazing. Really shows the value of overhangs,
| breezeways, and trees.
| rsync wrote:
| Whole house fans are really great.
|
| It's cheating, a bit, to live in a place that drops 20-40 F
| at night ... but even if we didn't, the ability to turn every
| open window into an air conditioner is a great trick.
| tguvot wrote:
| Yes. It's really amazing. First thing that I did after
| bought house last summer was to install whole house fan.
| Due to it we used hvac to cool house for less than 36 hours
| in July-October timeframe (only at days when temperatures
| were above 40 for few days in a row or when night
| temperatures didn't went down below 20)
| bluGill wrote:
| I'm going to tear mine out. It helps a little, but it leaks
| so much conditioned air when not in use i'm convinced it is
| a negative overall.
| tguvot wrote:
| tear it out and put a new one. There are models from
| airscape that come with motorized dumper doors with
| insulation. When fan is off, it's sealed.
| wil421 wrote:
| It doesn't work. People use electricity at peak hours because
| working people and families are on similar schedules. We all
| get home from work or wfh office, start cooking, and doing
| other things because we have time after work/school. Not to
| mention 5pm is usually the hottest part of the day so ACs run.
| ceejayoz wrote:
| It does work, though. Nest's program pre-cools to get you
| through the hottest hours without having to kick on the AC,
| moving some of the region's demand from the 4-6pm slot to the
| 2-4pm slot.
|
| I find myself going "huh, it's getting a little warm" at
| about 5:45pm, at which point I check and remember it's a
| "Rush Hour" session.
| rblatz wrote:
| Does precooking really work? I'd assume it would have to
| cool my house down below 65 to keep it below 80 all
| afternoon. 111+ days are brutal in certain rooms even with
| both ACs set to 76.
| dragonwriter wrote:
| > Does precoo[l]ing really work?
|
| Depends on the shape of the temperature graph for the
| day, the power of your AC system, your insulation, etc.
|
| If your on a day that doesn't get below 90 and gets above
| 110 during the hottest part of the day and your AC is
| barely rated at the minimum recommended for your square
| footage and you have average insulation, no, and even
| regular AC use is going to be marginal and your AC is
| probably going to frequent service.
|
| (And the things that make precooling work better also
| will make your AC work better and, for the most part,
| more energy and maintenance cost efficiently when you
| aren't precooling.)
|
| If you live in a place where you frequently need AC,
| aside from decent insulation, getting an overrated, high-
| efficiency unit (which seem to be correlated for
| residential units, probably because both drive up cost,
| and there is a correlation between people looking for
| more capacity and people concerned with efficiency) is a
| serious quality of life improvement.
| reaperducer wrote:
| _Does precooking really work?... 111+ days are brutal_
|
| Not every solution works in every situation. That doesn't
| mean it doesn't work, it just might not work for you.
|
| (Posted from a location that was 108deg last week.)
| ceejayoz wrote:
| I would not expect this sort of solution to be super
| useful in a place that gets 111 degree days, where AC is
| literally keeping folks alive. You'd probably get more
| benefits from a housing code that requires extended roofs
| for shade, light colored exteriors, etc.
| smileysteve wrote:
| The last 30 years have been a renaissance of insulation
| and energy efficiency. Pre cooling, fan recirculation,
| humidity consideration, time of use observance may only
| delay/reduce a few cycles per house per day, but in
| aggregate, that's significant.
| BeetleB wrote:
| The silly thing is that I can simply adjust my thermostat to a
| lower temperature, so that the effective temperature is the
| same as without this program.
|
| As an example, if I set it to 74, then when Energy Savings
| kicks in, it may set it to 76, which is too warm for me. So I
| simply set the "standard" temperature to 72, and it will set it
| to 74.
|
| I use the same energy as without this program, yet I get my $25
| energy savings rebate.
|
| Silly.
| sokoloff wrote:
| It seems like maintaining a higher delta-T from ambient would
| require more energy, not the same amount. You are still
| shaving the peak demand with this approach, so the $25 could
| still be earned.
| BeetleB wrote:
| I'm not following. Peak event is, say, from 3-7pm. All my
| Ecobee does is set the thermostat to be a few degrees
| higher in that time period.
|
| So as soon as it hits 3pm, I change my thermostat to a
| cooler temperature, so that the final temperature is what
| it would have been without this program.
|
| Pretty much _exactly_ the same usage as without enrolling
| into the program. Same "spikes", etc. Without the program,
| it would be set to 74 continuously. With the program, it's
| set to 74 before 3pm, and then at around 3pm (or just
| before), I set it to 72 so that it will continue at 74.
| sokoloff wrote:
| I did not read "standard temperature" to mean "a thing
| that I manually adjust twice per day on a fixed schedule"
| but rather "I set it 2oF colder in April and leave it
| that way until November".
|
| If you are willing to make 60 thermostat adjustments per
| month at 42C/ each, you earned that $25 in my book.
| BeetleB wrote:
| Energy savings events in my area are rare - only a few
| days of the year and very predictable (usually on a "hot"
| day). It's not a burden.
|
| Prior to this program, the local utility company would
| merely announce the hours of peak events, and recommend
| minimizing energy usage as much as you can tolerate.
| They'd calculate how much less energy you used, and give
| a credit commensurate to that amount. I used to just
| chill at a nearby library during those hours (no kids in
| those days).
|
| With this program, all they do is check that I
| participated often enough to exceed a threshold, and I
| get a fixed rebate (regardless of how much I exceed the
| threshold). And I effectively get that rebate by not
| saving any energy, and with little effort on my part.
|
| It's silly.
| ceejayoz wrote:
| That's fine, really. The utility's concern is predictability
| and burst capacity, not raw usage, so they know when and how
| many https://en.wikipedia.org/wiki/Peaking_power_plant to
| turn on, which may take a while.
| BeetleB wrote:
| Not sure I follow. If they just want to know in advance,
| then they don't need to modify the temperature at all,
| correct?
| ceejayoz wrote:
| Lowering the load helps avoid needing the more expensive
| short term plants from coming online.
|
| Whether you go from 76 to 78 or from 66 to 68, you're
| helping avoid the burst in demand they'd get.
| BeetleB wrote:
| That's true, assuming I changed the temperature setting
| prior to the event, and I likely won't time it perfectly
| (nor would I want to).
|
| The real thing is: These events last for hours. If what
| you say is true, then wouldn't altering the thermostat
| for a small period (e.g. 30 minutes) suffice?
| copperx wrote:
| > but I believe they should be providing a system that
| proactively cools when there is less demand _prior_ to an
| expected increase in demand. Effectively using your house as a
| "battery".
|
| Isn't this exactly what they do? That what the Nest does when
| there's going to be a spike; it cools the house.
| Kirby64 wrote:
| The nest does this, but it's not very effective. We're
| getting the 'rush hour' stuff right now (it's 100-105 peak
| right now) and the Nest does the following:
|
| * Sets the thermostat 2 degrees cooler (74) ~1 hr prior to
| the rush hour time (3:30-5:30)
|
| * Sets the thermostat to 4 degrees warmer between rush hour
| timing.
|
| Problem is, with the current heat my house cannot be cooled
| down to 74 1 hour prior, and even still... it floats up to 80
| degrees by ~4:30-5PM anyways and the AC kicks back on. Then
| it takes until ~10PM or so to get BACK to the 76 set
| temperature. This is a relatively modern house (built in
| 2010s), so it has modern insulation, sealing, etc. It's just
| ACs aren't really sized for being able to wildly swing
| temperatures and maintain temp. When it's 100+ degrees
| outside, they're sized so they run basically constantly when
| the sun is out, so slipping temperature means you're playing
| catch up for the rest of the night.
| evanreichard wrote:
| > Isn't this exactly what they do? That what the Nest does
| when there's going to be a spike; it cools the house.
|
| I don't have any experience with Nest, but the Ecobee seemed
| to just increase the cool set temp when there was demand. I
| didn't experience any proactive cooling.
|
| Interestingly, in the Ecobee Community Energy Savings FAQ I
| linked above it says:
|
| > [...] your thermostat may precool your home prior to the
| event to make sure you're comfortable.
|
| But I never experienced this. I wonder if its energy provider
| dependent.
| ceejayoz wrote:
| Nest's does this; it cools below your set temperature in
| advance of the "Rush Hour" for a few hours.
|
| https://support.google.com/googlenest/answer/9244031
| supportengineer wrote:
| This feature actually makes my house uncomfortably cold.
| hwbehrens wrote:
| In my experience, it was not nearly sufficient. If your AC is
| appropriately sized (or undersized) for your house, you can't
| just drop several degrees in 2 hours during the hottest part
| of the day. Going from 78 to 72 to 84 in set temp looked more
| like 78 to 77 to 83 in practice. Granted this was in AZ in an
| older house, so extremely high outdoor temps combined with
| marginal insulation didn't help.
|
| If they pre-cooled the night before it might be a different
| story.
| ceejayoz wrote:
| I think a poorly insulated old house in Arizona is probably
| one of the worst-case scenarios here. Maybe there should be
| a configurable or learning-based pre-cool length, though.
| moralestapia wrote:
| >Sorry, not sorry: I'm not willing to sacrifice my comfort for
| the ~$10/mo incentive.
|
| Hey, but at least you don't use plastic straws, right?
| saurik wrote:
| Why would you expect someone who isn't willing to sacrifice
| their comfort for a $10/mo incentive to sacrifice their
| comfort for a $0/mo incentive? Deciding "I don't like this
| person's ethics" doesn't mean "this person is suddenly
| inconsistent": you need to check your knee-jerk responses :/.
| kennywinker wrote:
| Well, for one thing people will often do for free things
| they wouldn't do for money. Imagine choosing between "i
| will pay you $10 to come to my party" and "i'm having a
| party, will you come?".
| philwelch wrote:
| Parties are supposed to be fun, so if someone offers to
| pay you to come to a party, that sends a signal that the
| party is not, in fact, going to be fun at all--otherwise,
| why would they pay you?
|
| On the other hand, paper straws are a shitty product that
| are unsuitable for use, but if I was offered a
| significant discount on beverages that were served with
| them...well, I wouldn't take it, but I could imagine
| someone who was desperately broke considering taking it.
| kennywinker wrote:
| See, what you said is exactly the problem i have with
| mainstream climate solutions. The choice shouldn't be
| paper straws vs plastic straws. The choice should be no
| straws vs straws. Similarly, the question shouldn't be
| "can I run a/c slightly off peak" rather it should be
| "how can I run less a/c". This applies all over the
| place. Electric cars have lifetime emissions that are
| lower, but in the same ballpark as ICE cars - if everyone
| switches to electric and changes nothing else, we still
| have climate change.
| baxtr wrote:
| Someone who works at a bar told me recently that they
| "discovered" long tubular pasta (forgot the exact name) to be
| the best organic straws.
|
| PS: You're welcome.
| mcronce wrote:
| The bar I frequent uses straws made of biodegradable
| material derived from sugarcane - they last a lot longer
| than paper straws, but ultimately are water soluble and
| will dissolve after a day ish if submerged. They obviously
| cost a lot more than plastic, but the user experience is
| just as good without the forever waste.
| Nextgrid wrote:
| From an ecological point of view it really depends how
| much carbon is emitted during manufacturing & transport.
|
| Landfills aren't actually _that_ bad when it comes to
| getting rid of waste. If you expend more carbon using the
| "eco-friendly" straws than using the normal ones then
| it's not worth it overall.
| namecheapTA wrote:
| The plastic straw thing confuses me. I'd like someone to
| explain to me how anything besides the random runaway straw
| gets into the ocean. I live 60 miles from the ocean. We're
| people throwing them into storm drains that flow to the delta
| that flow to the ocean? We're people in San Francisco
| traveling to the beach and throwing them into the ocean?
| Couldn't we focus on not littering instead of legislating
| things like straws?
| gedy wrote:
| Plastic trash is mostly from a few sources in Asia. China
| and Indonesia iirc.
| bedast wrote:
| I have an ecobee and keep it in a fairly dumb scheduling mode.
| My primary use, as of now, is to integrate with home assistant
| so I can have data at hand to make future decisions on energy
| and system usage.
|
| I tried something similar with Nest but holy crap is it a pain
| in the butt to integrate with home assistant, and keep the
| integration functioning.
| evanreichard wrote:
| > [...] integrate with home assistant so I can have data at
| hand to make future decisions on energy and system usage
|
| This is actually what I've been doing. I haven't done
| anything actionable with the data yet, though. Beestat [0]
| has some great data break downs as well.
|
| On a similar note: My house is only a single zone and I've
| been manually adjusting the dampers when fall / spring come
| around. When I find some time, I want to try to build
| something that will automatically adjust the dampers based on
| where I am in the house to create a pseudo multi zone setup
| with Home Assistant.
|
| ___
|
| [0] https://beestat.io/
| MonkeyMalarky wrote:
| Like heating/cooling your house more in advance of demand? It
| would be neat if they could enable/disable demand on a rolling
| basis where AC runs for one subpopulation for part of an hour
| then for another subpopulation the next part.
| Robotbeat wrote:
| You don't need to do that with any kind of precision. Random
| starting and stopping has the same effect over a large number
| of households.
| celticninja wrote:
| or you know, dont live in the desert e.g Phoenix Arizona, or
| if you do decide to live in the desert then realise that's
| your choice and dont add to pollution and climate change by
| trying to cool down a desert with AC.
| xyzzyz wrote:
| Do you also recommend that people don't live anywhere it
| snows? I mean, heating up in winter uses even more energy
| than cooling down in summer.
| seiferteric wrote:
| It's funny that I have seen several anti A/C articles and
| several pro Heat Pump articles in recent times, do you
| think they know these are the same things in reverse? At
| least A/C is often used in sunny locales were solar can
| be used effectively.
| MonkeyMalarky wrote:
| Same thing in reverse but where I live, in the summer I'm
| cooling from 30C down to 20C and in winter I'm going from
| -18 to 18.
| mulmen wrote:
| Were they from the same people?
| wiredfool wrote:
| AC is more than 100% efficient in heating the
| environment. This is unfortunate, but thermodynamics will
| win in the long run.
|
| Heat pumps are more than 100% efficient at heating the
| house, which is what we want, and one of the places where
| we are on the same side as thermodynamics.
| doubleunplussed wrote:
| In the long run ACs are exactly 100% efficient at heating
| the environment. The extra heat is only temporarily
| displaced from the building being cooled, and will leak
| back in eventually.
| kennywinker wrote:
| There is heat generated by the system, and heat generated
| by the power generation used to power the system. It's
| definitely not a neutral system - that'd be
| thermodynamically impossible ( increasing entropy without
| external energy)
| Nextgrid wrote:
| If you power the AC with 100% solar shouldn't there be no
| extra heat generated?
|
| As in you're merely absorbing some of the heat from the
| sun to then move existing heat around?
|
| Frankly, even without solar power it wouldn't generate
| "extra" heat directly over a long timescale, it would
| only accelerate the release of existing "heat" currently
| trapped in oil/gas/nuclear/etc.
| seiferteric wrote:
| Fair enough, but direct heating of the environment is not
| of practical concern since it's effect is minuscule
| compared to GHG's. Point being, solar output is well
| correlated with A/C usage, which is a nice benefit and
| all that solar energy would be turned to heat anyway...
| so might as well have it cool your house :) Heat pump in
| the winter on the other hand, not so well correlated with
| renewables.
| [deleted]
| Navarr wrote:
| Google is currently doing a proactive system called "Nest
| Renew"[1]. This system is more focused on using clean energy
| vs. dirty energy - at least for me (where there is no rate
| difference based on time)
|
| [1]: https://nestrenew.google.com/
| r3trohack3r wrote:
| Ecobee integrates with SRP in my area and does exactly what you
| describe. They know my billing plan (Time of Use - Demand) and,
| from my understanding, will coordinate with SRP ahead of a
| conservation event to pre-cool my house by up to 2 degrees
| before raising it by up to 4 degrees when attempting to
| "flatten the demand curve" of the grid.
| jjtheblunt wrote:
| Our ecobee (Phoenix, so HOT) does the precooling and is buggily
| aware of the expensive time window for electrical rates.
| Arizona Power just shrunk the expensive time window, not sure
| how that made sense, but the ecobee seems to not know, nor is
| there any way i could find to inform ecobee of the new shorter
| expensive time window.
|
| I've had two Nests before, and two Ecobees, and they both were
| fine, in general, but for the next house not sure which I'd
| prefer.
| bfgoodrich wrote:
| jandrese wrote:
| Nest has an energy saving feature that feels like it is trying
| to boil the frog. We normally keep the thermostat at 78F
| (~25.5C), but over the course of a couple of weeks it ticked it
| up to 79F, then 80, then 81, and now 82F (~28C). I had to go in
| and manually adjust the schedule to get it back to something
| reasonable.
| hyperdimension wrote:
| An interestingly more literal use of the analogy. I like it.
| LazyMans wrote:
| Where do you live? I'm just curious because I can't imagine
| living at 78F anymore.
| s1artibartfast wrote:
| Seems pretty normal to me. Maybe not as refreshing if you
| come in out of working in the heat, but fine for being a
| desk jockey.
|
| Temperature Comfort is largely a learned behavior in my
| humble opinion
| jrs235 wrote:
| In Wisconsin we set the AC to 78 in the summer. We tried
| doing that when we moved to Florida. Couldn't do it. Had to
| go down to 72, 74 max, because of the humidity. There's
| just too much moisture in the air and we have to set the
| thermostat that low to make sure it gets removed from the
| air.
| jffry wrote:
| I'm not OP but I live in Washington DC, where our summers
| are definitely hot and humid. I keep my apartment around
| 78F to 80F. I use a dehumidifier to keep relative humidity
| around 50-55%, which corresponds to a dew point of ~60F
| which is low enough to still feel comfortable instead of
| "sticky".
|
| On especially hot days, I will raise the setpoint higher,
| and use a small fan to circulate air around where I am
| spending time, which is very effective when humidity is not
| too high.
| hachari wrote:
| A dehumidifier is essentially an air conditioner that
| dumps heat back into your living space.
|
| What you are doing sounds inefficient.
| jrs235 wrote:
| Yep. They're adding heat to the inside of their home.
| They need to use an AC unit to remove the moisture and
| pump the heat outside.
| jffry wrote:
| I do have an air conditioner (well, an air-source heat
| pump), but it doesn't adequately remove enough moisture
| before the indoors gets too cold. It's possible this is
| not properly sized, but I cannot change it because I
| rent.
|
| In my case I did some tests, and the additional power
| usage of the dehumidifier is way more than offset by the
| power savings I realize by running the air conditioner
| less frequently. This only works because the dehumidifier
| enables me to be comfortable at a higher indoor
| temperature.
| jffry wrote:
| The dehumidifier does use power and produce heat which
| must be removed from my apartment by the air conditioner.
|
| Because it's less humid, I can maintain a higher indoor
| temperature and still be comfortable, meaning the air
| conditioner needs to run less.
|
| Do I use net less energy? In my case, yes, but your
| mileage may vary depending on your equipment, insulation,
| etc.
| google234123 wrote:
| 78-80 doesn't feel to bad in a dry climate imo
| jandrese wrote:
| I live in a fairly humid area, but the AC helps to drain
| the moisture out of the air so it's still livable.
| Ceiling fans on a low setting can also help you feel
| comfortable, especially if you don't have the sun shining
| on you.
| lfowles wrote:
| 78 at my thermostat means some rooms in the upper floor
| might be 84+!
| popcube wrote:
| Is it too high or low? I am interesting about condition
| settings of foreign!
| chamanbuga wrote:
| Holy, while in Toronto I set the thermostat to 68 and
| complain if I see it cross into the 70s. Thanks to the wind
| tunnel I'm in, I'm able to turn off the AC every 2-3 days for
| 1-2 days. Conventional wisdom tells me this is more costly
| than just keep the AC running all the time at a stable
| temperature, but, I don't really care about the cost saving
| over personal preference.
| NelsonMinar wrote:
| Thundering herd, but for thermostats. A little randomization of
| the default setting would go a long way to smoothing out the
| spike.
| cratermoon wrote:
| Sounds like they need to program them with something like
| exponential backoff and retry with jitter. Do the smart
| thermostats have any information on grid demand? IF not, then
| they could just be programmed to apply some random time shift +/-
| a few minutes (or however long) to spread out the demand and
| lower the spikes.
| sporkland wrote:
| Came here to propose jitter as well:
| https://en.m.wikipedia.org/wiki/Jitter
| indigomm wrote:
| Don't smart thermostats take into account how long it takes to
| change temperature? Mine certainly does. Since each building will
| have different properties, they effectively have jitter already.
| I therefore don't see this as an issue.
| moffkalast wrote:
| Energy companies like to complain about demand spikes instead
| of doing their job and managing the grid properly. Like if
| bakeries were complaining that they have to get up at 5 to bake
| bread because people want it in the morning or something.
| mdasen wrote:
| There will certainly be some jitter, but it'll be like rush-
| hour traffic. Sure, some people get in a little earlier or
| later and they leave from different points, but the result is
| that we still have traffic that peaks. I don't think the issue
| is that everyone is turning it on at the same time.
|
| For example, let's say that people have dumb thermostats and
| they turn them down 2 degrees overnight - because you don't
| want to turn it down too aggressively since it won't warm the
| place before you wake. They wake up and turn them up 2 degrees.
| There's jitter so it's not all at once. The home heats up over
| the next 20 minutes and the heating turns off. Let's assume
| that everyone wakes up evenly distributed between 6am and 7am.
| The grid is handling 1/3rd of customers (or less) at any given
| time. By minute 20, 1/3rd have turned on their heat, but by
| minute 21 the first 1/60th of customers have their systems turn
| off.
|
| By contrast, let's say that people have smart thermostats and
| they turn them down 6 degrees overnight. The thermostats
| likewise introduce jitter and we'll say they evenly distribute
| over a 1 hour period. Given the greater amount that they need
| to warm the place, they'll each be on longer - let's say for an
| hour even though degrees aren't linear. Half of them start in
| the first half of the hour so by minute 30, you're dealing with
| half of the customers running their heat - but because there's
| longer to go to heat up a place 6 degrees, none of them are
| shutting off. At minute 31, now 31/60ths of customers are
| running their heat. Then it's 32/60ths. This continues until
| we're at all customers with the heat on simultaneously. We'll
| be at 50/60ths usage for 20 minutes which is 2.5x more load
| than the other example.
|
| This principle holds regardless of different building
| properties or increased jitter. A greater percentage of people
| will have their heating systems on at any given time in the
| morning due to this.
|
| This is important because it means that it increases the
| likelihood that utilities need to run so-called "peaker plants"
| that are more costly to operate and pollute more to handle the
| load.
|
| Sometimes utility companies offer incentives around avoiding
| this problem. I believe some California utilities have
| incentives for charging your electric car overnight when the
| load on the grid is minimal - because it's cheaper for the
| electric company to supply electricity then. Likewise, it would
| be cheaper for the electric company to supply electricity for
| heating then. Some electric companies have off-peak rates. Some
| electric companies have incentive programs where you can enroll
| your smart thermostat with them and they can shut off your AC
| for an hour when they're trying to shed load (you can override
| it, but it can help them shed load from lots of people who
| don't notice a degree or two change).
|
| No, everyone won't be turning on their heating at the same
| time. However, if everyones smart thermostats run the heating
| system for 2 hours in the morning rather than 20 minutes in the
| morning because they more aggressively manage the overnight
| temperature, there's going to be a lot more overlapping
| running. This usage will overlap with other peak-hour usage
| like hot water heaters, toasters, microwaves, stoves, and
| businesses opening up - compared with overnight heat usage when
| businesses are closed, people aren't showering or making food,
| etc.
|
| The answer is probably smarter smart thermostats. They turn
| themselves down overnight, but then the electric company
| manages the overnight temperature so that they don't face a
| morning rush to heat and have to use peaker plants. This would
| be done with consent of the users and within ranges specified
| by the users and to the user's benefit in terms of saving money
| - ie. the person wouldn't have to pay more just because their
| heat was kept a bit higher overnight and it wouldn't be kept
| above their comfort level. Likewise, users could opt into a
| program where they might be able to save money (say $5-10/mo)
| with the note that during peak times their home might heat up
| more slowly than it otherwise would - if it would normally take
| an hour to go from 60F to 68F, maybe it takes 1.5 or 1.75
| hours. Again, that would allow the utility company to shed load
| while not inconveniencing consumers too much and providing
| adequate compensation for what is an inconvenience.
|
| Electrifying our heating can mean that our heat starts coming
| from sources like wind and solar rather than gas and oil.
| However, it'll also provide some challenges around peak-time
| usage. These aren't insurmountable problems, but they do exist.
| gwbas1c wrote:
| Probably makes more sense to incentivize residential batteries
| that can help take the strain.
|
| The batteries can charge when there's a surplus of power on the
| grid, and then absorb the load when everyone turns on the heat/AC
| at the same time.
| aaron695 wrote:
| navi0 wrote:
| As one of the authors of both the Zigbee Smart Energy Profile v1
| [0] and the pre-IEEE seed that became P2030.5 Smart Energy
| Profile 2.0 [1], we did anticipate this and included a randomized
| modifier to any demand response or price signals coming from the
| grid to provide the "jitter" discussed in other comments.
|
| The problem here is that these thermostats have NTP-synched
| clocks and come with default schedules out of the box and failed
| to consider the importance of staggering over a 5-min time
| period. It's understandable from a consumer acceptance standpoint
| ("I set it to start at 6a, why did it turn on at 6.03a?!"), but
| that could be solved with some messaging.
|
| Better still would be for future thermostats to be required to
| connect to the Internet and to the grid's price signals or
| utility's servers in order to receive rebates. This would see
| them base behavior on pricing signals, which would include a
| device-specific random offset to the price taking effect.
|
| Resideo (formerly Honeywell Home) acquired some very cool tech
| that would solve this issue, too. Developed by Whisker Labs
| (formerly WeatherBug) It combines a weather feed with a custom
| thermodynamic model of each home to adjust the start time of each
| setpoint. This provides both energy savings and more comfort. For
| example, if it's an abnormally cold Feb day, it would start the
| heater earlier to reach the desired setpoint rather than a normal
| thermostat starting at a precise time and hitting the setpoint
| later in the morning.[2]
|
| Final fun fact: ~40% of smart thermostats never get connected to
| the Internet. Many people are price insensitive enough to buy a
| communicating thermostat and just slap it on the wall without
| bothering to program the Wi-Fi settings. There are sneaky ways
| some manufacturers and ISPs are trying to overcome this, though
| it's a borderline dark pattern. [source: I used to work for a
| large ISP's connected home ecosystem team]
|
| [0] https://zigbeealliance.org/wp-
| content/uploads/2019/11/docs-0...
|
| [1]https://standards.ieee.org/ieee/2030.5/5897/
|
| [2] https://www.resideo.com/us/en/corporate/newsroom/all-
| article...
| cosmotic wrote:
| This problem is entirely industry created. The tech to mitigate
| has been around for what seems like 30 years. There's just no
| industry cooperation.
| s3ctor8 wrote:
| If a smart thermostat is turning on at a factory set "default
| time", I wouldn't consider it to be doing its job of adjusting
| the timings based on your usage habits.
| SketchySeaBeast wrote:
| I don't know how the smart thermostat is supposed to know your
| behaviour unless you tell it, which means taking it off the
| default. I had to tell my thermostat explicitly when I wake up.
| ctdonath wrote:
| With room occupancy detection, it should start modeling
| likely HVAC needs - able to predict accordingly, and adjust
| power use & timing jitter accordingly.
| SketchySeaBeast wrote:
| Ah, that's another level of smart than I was thinking of
| and requires integrating motion sensors, but I do suppose
| that would enable it.
| TeeMassive wrote:
| I work on a project where we design devices that offload certain
| power intensive devices from the local grid when the current is
| getting too close to the power limit of the transformer's limit
| so they don't have to send someone in the field every time.
|
| We have a minimum 15 minutes delay before powering back on a
| device that was powered off.
|
| I've raised the issue where there could be a problem where there
| might be a ressonance effect with our devices and similar smart
| grid devices from other sources due to the 15 and n x 5 minutes
| delay being ubiquitous.
|
| For now we came to the conclusion that this not an issue, but I
| still think this is an easily avoidable catastrophe that can be
| easily mitigated by adding a random offset to the delay.
| nick238 wrote:
| One of my existential worries before IoT devices were at least a
| _little_ security-aware, was if there was a large coordinated
| attack where someone would constantly power on /off tens or
| hundreds of thousands of AC units in a region causing a blackout
| like the 2003 Northeast blackout.
| twawaaay wrote:
| Seems like a problem that can be easily fixed with a software
| update.
|
| Just add a little bit of jitter into start time.
|
| Do people need their thermostats to be punctual? I don't think
| so...
| 0xbadcafebee wrote:
| Keep morning clothes on an electric blanket with a smart plug
| timed to turn on before you wake up. Get out of bed and put on
| piping-hot pants. Timer on your coffee maker makes either coffee
| or tea (put tea bags in the coffee pot) as you wake up. Make a
| hot breakfast in the microwave (oatmeal for me). No need for a
| thermostat change for hours.
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