Does a smart home really help save energy?

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#1

Hi guys, I thought I would open this discussion to get your opinions on this topic.

As I’ve been going over our “smart home” installation lately, it occurred to me if it really helps save energy in any way. When you see advertisements of smart home devices, you always read about “energy saver”, “helps save energy”, etc… But if I include the resource consumption for additional sensors and devices, the energy consumption of a home server + batteries, etc. in the calculation, I’m not sure how big the energy advantage is compared to a “dumb home”.

For me personally, e.g. smart radiator thermostats are the biggest nonsense, which is always sold as energy savers. Until recently, I had also a few of them in use, but since normal radiator thermostats, at least here in Germany, have a mechanical/chemical temperature sensor that locks off at a certain level and temperature, they seem kind of useless to me. + That they need new batteries every year and the change in room temperature usually reacts too sluggishly, as you could really control it in the short term.

I have also done some research, but so far I have not been able to find any studies that would really prove the energy savings from a smart home installation.

Therefore, I would be interested here once your opinion. Is a smart home really an energy saver for you, or does it also mean more of a playground and more comfort for you?

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#2

Smart radiators valves save me a lot, as it allows me to reduce the temperatures in some rooms at scheduled times and to heat less if the weather is expected to be warm.b also based on presence it will reduce the temperature in rooms savoring water when we are out.
Standard trv are just set at a temperature and can’t make those savings.
Saves me around 40%

#3

Hi @samnewman86 thank you so much for your feeback!
What exactly do you mean by 40%? How did you measure consumption here before and after the smart home installation? I have experienced that when I changed the temperature at certain times, or based on presences, it hardly reflected in our overall balance of the heating system.
On the contrary, when I reduced the temperature significantly, e.g. 16°C when I was absent instead of 22°C when I was present, the energy consumption for heating up was higher than if the radiator had been running at 22°C all the time. For the optimal case, I could only vary the temperature by 2-3°.

#4

You don’t have any teenagers in the house ? I started home automation because I noticed, when I had to go for a pee in the night, all the lights in the house would be on, because the children would turn the lights on, but always ‘forgot’ to turn them off. I definitely have cut down on the electricity bill since then.

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#5

Controlling radiators based on occupancy saves energy and money. Link them to a window sensor and they will turn down on opened windows.

#6

Usally I just turn them off, when I open a window. So ist’s just more a comfort thing :wink:
The question here is rather whether the Smarthome devices are superior to human forgetfulness :smiley: @francisp had a very good example of this :wink:

#7

This discussion reminds me of

A wifi smart plug on the toaster…
That will save you energy for sure :laughing:

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#8

Here in Switzerland most of the buildings (at least newer ones) have floor heating. As floor heating takes a pretty long time to heat up, it doesn’t make sense to lower the temp when we are out of the house (except if you go one vacation), and as you said it usses more energy to heat it up than to run it constantly.

However I was able to cut the energy bill a bit with smart lighting, but I don’t think this saving covers the money I spent on smart home gear in the next 10 years :rofl:

For me the smart home is more for comfort (lights turning on/off when needed, notify on different things such as the dishwasher being finished, music following me around the house etc.) and security (water leak, invalid login attempts, alert on motion when away etc.).

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#9

I’m sure my smart home does not save any energy.
I have nothing that really saves energy.
Possibly outdoor lights that turn on based on sunset instead of by time only, that could save some energy by not turning it on too early, but really…

I do smart home for comfort. I can speak out to set egg timers and it will alert me when the eggs are done.
I can disable the tablets so that my 4 year old can’t use them, that way I don’t have to run after him and see if he is still using the tablet.
Turn on and off the alarm automatically, speaks out waze notification in the speakers as I leave work, keeps the chromcast alive when we need to take care of the little one and so on.
It’s all those small things that makes a big difference

I don’t have any numbers on how much my smart home consumes but whatever the cost is it’s worth it.

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#10

One of the best sensors I installed was the hot water temperature. We have solar water heater system but when there is no sun we have to use electricity. Right now everyone in the house knows if there is available hot water and how many people can take a bath for example. Usually the members of the family turned on the water heater every time they wanted. These days we use the water heater at least half of the time we used to. Further more I have an automation that turns off the water heater when the water temp. reaches a certain point. All the above saves us a lot of money.

Now that I can measure how each air condition (for heat or cold) consumes energy I made adjustments and for the last 3 months the total energy for heat (from air-conditions) it is reduced at least 20%.

I have enough smart plugs in many appliances that consume energy in stand by mode. In the goodnight routine I turn them off and automatically the next morning turn them on. Before that, the night electricity consumption was 1.4 kwh and is 0.65kwh which adds up in a yearly bases.

I think/hope that in 2-3 years I will eventually earn back the cost of the devices of my smart home.
Nevertheless, the “smart home” is a great comfort in many aspects in the every day living, and a great hobby too to keep me busy and happy

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#11

As others have stated, I too implemented Smarthome technologies because all of my family members can’t seem to turn off lights. After implementing motion lighting my electric bill went down by 10%. Not great but better than the lights staying on and shortening the lifespan of LED bulbs and power consumption 24hours.

My biggest savings was finding the large vampire sucking devices like Xbox, computer monitors, TVs and such. I cut my bill in half implementing $10 Kasa outlet controllers and automation with Alexa/HA/harmony. I save ~$90/mo compared to before.

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#12

I saved a lot of energy (home heating oil) when I went to “smart” thermostats. I have hydronic baseboard heat, and recovery time is quick enough that any time the temps can be lowered for a while is helpful. I do agree that for systems with very long recovery times the savings won’t be as large, although any time you’re not heating a space there should be some savings.

How many of these devices do you have? What is your electric rate? The only way I could even spend $90/mo on electricity (never mind reduce it by that much) would be to run a lot of electric resistance heaters. Even running my hot tub only adds about $40-$50/mo to the bill.

And, of course, there are parasitic loads from all the smart devices, too. These are smaller than the loads from TVs and such, but there is some cost there. This becomes an issue on an RV or boat, when you have to run for long periods on 12V batteries, but in a home, it’s usually not noticeable.

#13

No teenagers required. My wife seems incapable of turning anything off.
For her, lights have an on switch but she can’t locate the off switch at all.
Except she occasionally turns off the Microwave (constantly having to reset clock)
AND for ‘some unknown reason’ she unplugs (not just switches off) the coffee grinder. (Edit: I don’t really care about this, so have never mentioned it to her :smiley: )

Simon, I have energy bills going back over 6 years. (with recorded values monthly)
Over the first 4 years consumption (in kWh) both for Gas and Electricity varied between 4 - 6 % year on year
The first year of home automation saw my electricity usage drop by 4% (from the previous running average) but that ‘may’ just be normal fluctuation.
My gas usage went down 23% This is based on switching the heating off if a door or window is open, To a minimum setpoint if we are more than 1500m from home, 18° during the day (when we are active), 19° in the evening (when couch potatos rule ! ) and 17.5° at night (we are in bed)
These figures are moderated by the general level of ‘moaning’ in the house (anything for a quiet life)
But with data it’s good to point out that “This is the same temperature setting as yesterday and you didn’t moan then”
This 23% reduction may be due to climate variation but I’m not sure ‘global warming’ can claim the credit.
This year will be interesting but I’m ready to discard any numbers due to the pandemic and us being home a lot more often (ALL the time it seems).
Im toying with the idea of turning each room into it’s own climate entity (though doors and windows will still act globally as I don’t monitor internal doors) The vlaves would be solenoid operated (no batteries) and the boiler switched from any one valve being ‘on’
Smart meters don’t have to enter into it, there is big noise about ‘energy savings’ but you only get that if you act on the data (ie change behaviour). Automate and you are halfway there. When they complain that the house is cold point out “What is the point of heating a room with it’s window open ?”

That’s high, current recommendations are a 20° max and can be reduced to 19° if you just wear a bloody jumper !

That’s rubbish !

Just think about it. Heat Loss is proportional to temperature difference.
This is why they now recomend 19°, Every degree added increases energy consumption by a given percentage based on the insulation of your property (most recent figures I saw (about 8 years ago) was 11% increase per degree C (this was for a full code compliant new house, most would likely be higher) So you loose heat inversely proportionately as the property cools (less differential and therfore the gradient reduces).Heating it back up just takes the energy to re-establish the gradient you desire - 19° on the inside, -6° on the outside (or 11° under your floor) or whatever.
Integrated over time there is NO WAY that this equates to maintaining that differential continuously, the mathematics just doesn’t support it.
There are reasons for maintaining minimum temperatures (frost protection, dampness etc.) but these can be mediated (minimum settings to protect pipes, dehumidifier for your home etc.).
Edit: assuming you have ‘good’ insulation and an efficient boiler you are paying 37% more to heat your house @ 22° than you would if you ran it @ 19° )

I’d like to see your maths for this. I appreciate that you ‘may’ have to deal with ‘lower outside temperatures’ but if you are about to leave the house for (say) 8 hours and your house takes 2 hours to heat to 19° from 14° why would you not turn the heating off for as long as possible ? You just need to monitor the internal temperature, work out the heating and appy it an appropriate time prior to arriving home (basically the car heater issue we dealt with 14 months ago).
I’m lazy and just use my distance from the house to trigger it.

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#14

It’s more in the range of 3-5 hours, large rooms with oak wood floor take a long time to heat up. In addition it takes up to 1-2 days until the floor cools down completely. For floor heating it’s the most efficient to let it run late fall until spring
Also most of the time (at the moment anyway) the house is not empty for more than 4-5 hours, my wife spends her lunch break at home most days of the week, I do Home Office 50% (100% currently) of the week.

#15

So the most efficient thing would be to reduce the set point early evening until early morning.

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#16

I connected a KW monitor on each device to determine the amount of vamping. An Xbox One running even in “standby mode” costs $12-15/mo. We have 6 TVs and they all cost together $10/mo sitting idle. Then we get to computers and monitors. All draw 3-4amp while “power saving” and we have a total of 8-27” monitors supporting 3 computers. Another $10-12/mo. Then we have some other things like heaters in rooms that get left on (I use a Zooz appliance switch) and turn those off when there is no motion or that human who usually uses that room is away. Overall, you can save quickly when you figure out where the power draws are occurring.

#17

It definitely saves me a lot on heating (and to a lesser extend cooling in what they call ‘the summer’). I’m heating with wood and electricity. Electric heating is very common in rural France (cheap nuclear energy helps). Until I find a robot shoving logs into a fire for me, I only automate the latter.

My house is a several century old farm with buildings made of stone (think rural cottage kinda thing) with a lot of thermal inertia and pretty bad thermal insulation. I initially thought that keeping the heat up when we’re away during the day would be more energy efficient, as it would be stored in the thick stone walls. But the cooling capacity of the world outside largely exceeding my heating capacity inside, combined with losses and general thermal funkyness of the house, I realized I was wrong. I easily save 20-25% on heating when controlling it through presence and night schedules.

I don’t save on lighting at all. I don’t see the point since LEDs are everywhere. If you leave them on for a night, so what. I don’t like motion controlled lights inside, they annoy me. Lighting automation is more about convenience for me and mostly about outside lighting. Most of my inside lighting is just plain old dumb light switches.

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#18

Hang on, from what you said it takes longer to cool than to heat, so your themal inertia is high and your insulation pretty good. So you can afford to do some tests.
How far away are your places of work ?
Can you heat based on leaving work ?
Else you’d need a time schedule updated for changing work patterns (calendar based perhaps ?)
Is your heating gas or electric or oil ? (all electrical heating goes to heat, with others some gets thrown out the flue) the point is if electric then you can have some spot heaters just to warm the air to reduce your recovery time.
What is a typical heat on off mark-space ratio ?
Try switching your heat off for an hour what temp loss do you get ?
How long to recover that at the end of an hour ?
I think you will be surprised at the results.

Test for different outside temps build a pattern

#19

I living in Almería (Spain). We have 300 sunny days to year, so, for heat water, a I have a solar boiler.

Home Assistant control the electrical heater support. When the water is cool and is cloudy, turn on the the electrical heater, but, if we will have a sunny day, don’t turn on because the water will be heat with the sun.

Using zigbee devices, the power consumption in standby is very very low, so, save one hour of light it is enough to compensate the consummation of the standby device.

For example, my motion sensor (aqara) it is running for 3 years with one battery…

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#20

OK, I’m trying to work out your math. You mention the costs in $, so I’m assuming you’re in the US, where the average electricity cost is 13.19 cents per kWh. If that’s wrong, or you’re in an exceptionally expensive part of the US, then all my calculations are off, but the same methods could be used.

Looking at the XBox, $12-15/mo is 91-114 kWh per month, or 3-3.8 kWh per day. That works out to 125-158 Watts continuosly. So, your XBox would get as hot as a 150W incandescent bulb. You wouldn’t be able to touch it, and it would probably melt.

For the TVs, 3-4 A at 120V is 360-480W. Again, that’s a lot of juice for a device which is powered off except for the remote circuit, waiting for input.

It’s been a while since I was in the business, but at work, back in the days of CRT terminals, we used to estimate something like 100W for a computer and monitor. Even powered on, the old desktop computers power supplies were only rated for up to 100-130W.

Certainly, electric resistance heaters are another story. They should have the operating Wattage printed on them, and that’s how much you’ll save by shutting them off.

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