How much does it cost to run a smart home?

I hate to break it to you, but your smart lights are not saving you any money. It doesn’t matter how smart the gadgets are, and how long you have spent crafting meticulously automated policies to turn things on and off when needed. Don’t panic (just yet), you probably adopted the biggest bill-saving tech already. If you want to know how much it cost you to run the smart home, I’ve done the maths for you.

EDIT (01/09/2022)
Things have changed a lot this year with electricity prices hitting 0.52p/kWh – this 5-fold increase over the tariff from 2020 could actually change my mind about potential savings. While in the past, running certain automation would hardly make any savings at all, increased electricity costs, could very well change the conclusion of this article in 2022. I guess this post has not aged well. The usage data still apply, so read on.

Smart, yes, but cost-effective?

I picked up a Yeelight 1S WiFi lightbulb from Banggood recently. The main selling point was a lower energy consumption compared to an older model while providing the same amount of light (800 lumens). The actual Watt difference was definitely impressive, but not staggering (2W), so it got me thinking. How much do I pay to keep my home “smart”?

In this article, I’ll focus solely on lights and supporting infrastructure. Not everyone has a smart fridge, a connected washing machine (or DIY smart washing machine like mine), or a smart door (yes I smarted up my door too). If you are into automation, lights and heating are probably the top priority (I made my 30 years old thermostat – connected for $5). Unlike heating, lights are simpler to calculate the running cost for and quantify the savings.

Testing over 30 IoT devices

There are more ways to automate lights, than just slapping a smart bulb into the light fitting. So I tested everything that could be used to smart up the lights I had at hand. From lightbulbs to multi-gang inline switches. Feel free to use these estimates

Testing procedure

I have a generic power consumption meter. It’s not lab-grade equipment, but a 3-digit precision and 2% error margin is good enough for the task at hand. The first meter gave up his life, and I ended up ordering a 2-pack to save the day! I plugged each device and monitored the power consumption in standby and operating mode. The results are noted below. Lastly, I have a fixed tariff for my energy plan at £0.187/kWh – money speaks better than kWh

Smart bulbs

I have tested several smart bulbs from different companies. Some are WiFi others are ZigBee based. All of them have to be powered on constantly. I measured the standby power and there are some interesting findings.

ZigBee lightbulbs are very energy efficient in standby mode. They can decrease the power draw significantly. IKEA TRADFRI range deserves praise, especially the 1000-lumen E27 light with white spectrum controls.

Smart Sockets

Sometimes it makes more sense to use a smart socket. These are also available in WiFi and ZigBee flavours. The advantages of using smart sockets are: easy to deploy, the ability to use the existing lightbulb works great for more exotic light sources. I tested smart sockets in 2 different states – where the socket is in standby and when the relay is activated.

Once again, ZigBee seems to be the best energy-saving protocol. Sonoff S31 socket came pretty close too, especially beating the IKEA socket when activated.

Smart wall switches

If you are keen on keeping the traditional method of turning the lights on and off, you could automate the wall switch instead. I have an entire article dedicated to wall switches and what you should consider before picking one up yourself. The major benefits are: keeping the switch operational and the ability to control multiple lights/bulbs with a single device. automating these would bring significant cost savings compared to using smart bulbs.

Looks like the current draw on these is very small. My meter was not able to measure Watts or mA in either of the states which means that the power draw was under the threshold. From the perspective of energy saving, these look ideal so far.

Smart switches

If you set on keeping the existing lightbulbs and switches, there is one more way you can automate the lights. These switches go either behind your wall switch or inside the ceiling fitting depending on how your lights are wired. Thanks to these, you can trigger the lights with smart devices and traditional wall switches. I compared some of them in this article in-depth.

Looks like the field is evaening out a little here. Even Zemismart Zigbee switch is not bringing significant energy savings. The only outlier was the Sonoff D1 dimmer – I guess dimming is expensive, as the other switches don’t have that function.

Smart inline switches

If your light doesn’t fit the above automation methods, you could simply add an inline switch to it. Sonoff is one of the more popular brands in this space thanks to the DIY mode and Tasmota. These come in various shapes and a number of relays.

By now, the values and calculations probably won’t shock you anymore. ZigBee leads the way. It’s interesting to see that introducing more relays to the boards, doesn’t necessarily offset all its running costs. 4-channel SONOFF can draw significant power to activate all its relays. Fortunately, it’s the standby mode that we are most concerned about and a 0.6W per 4 relay looks pretty attractive!

Basic controls

No home automation goes far without control points, so I have included a couple of items I run at home to control the outlets and lights. There are smart speakers, and a Raspberry Pi-based server with a ZigBee USB stick – everything you need to run above gadgets in a smart way.

Picking more power-hungry smart speakers will increase the bill even further. I have 3 Echo 3rd gen, one Echo 2nd gen and Amazon Show 8″ – all this adds up! Especially when the device is in active use (music, voice etc).

https://docs.google.com/spreadsheets/d/1NzAANusoaH8nNlLLvadVa_VyVOGJqRTjwWxztz35cJg/edit?usp=sharing

Average household power consumption

I will take some creative liberty here and I will assume that the average house with smart automation looks as follows (note that I’m still only considering what’s required to run lights only, you can imagine the added cost of blinds, thermostat, Chromecasts and other connected devices that you may find at home):

• 3 Bedrooms (one main, one lamp each)
• 1 Living Room (2 main lights)
• 1 Kitchen (2 main lights)
• 1 Hall/Entry (2 lights)
• 3 Amazon Echo 3rd gen
• 1 Raspberry Pi server
• 3 general-purpose smart sockets

It’s not a lavish example. Most of us probably don’t have every single room automated, but I think this list paints a decent picture of an automated home. With that said – let’s do the maths.

Worse case scenario:

It’s all WiFi. Router aside, we are looking at 12 light bulbs, 3 smart sockets and 3 Echos and a Raspberry Pi 4. The yearly upkeep (without keeping the lights on!) would be:

12 * 2.555 + 3 * 1.825 + 3 * 2.92 + 1 * 5.11 = £50.005  ($64.52)

That’s just to have everything connected and ready to be used. It’s a pretty high figure! We could play a little smart and replace the Kitchen and Living Room lights with a single wall switch:

8 * 2.555 + 2 *0.73 + 3 * 1.825 + 3 * 2.92 + 1 * 5.11 = £41.245  ($53.21)

Or go all-in, with ZigBee protocol, build up our mesh and take the advantage of the power-saving protocol and no neutral switches that don’t seem to take much power:

8 * 0.73 + 2 *0.00 + 3 * 1.825 + 3 * 2.92 + 1 * 5.11 = £25.185 ($32.48)

With some smart choices, we brought the energy use down by half! That’s an extra £25 you can spend on new ZigBee gadgets right?

Smart != Cost Saving

I have some bad news for you. If the goal is to save money, rather than provide the convenience of use, you may as well chuck all smart lights out. No amount of automation will lower your energy bill compared to not-connected LED lights (assuming sensible rather than flamboyant use).

Let’s assume that the average non-IoT lightbulb draws 8W of power when in use. Running this light 24/7 would cost you:

8W /1000 * 24 * 365 * 0.187 = £13.104 ($16.89)

That’s 2 bulbs turned on for 12h a day, or 4 bulbs running for 6 hours each day. You can make it 8 bulbs if you are running it 3h each day and so on. This means that you can “forget” to turn off 8 lights in your household for up to 3h of unused time per bulb, and still end up with a smaller bill than running smart home automation. No amount of toggling the lights on and off would lower the bill.

Of course, sensible automation rules will curb the further electricity costs associated with the use of connected light sources. I’m in no way trying to discourage you from coming up with creative use of automation to achieve the best results possible. If the goal is to keep the bill as low as possible, consumer automation isn’t the way to go.

Final thoughts

The numbers don’t lie. It’s not the “smart” or “connected” part that keeps the money in your wallet. It’s the associated LED technology that lowered power consumption tenfold. It enabled us to allocate that energy elsewhere. Your smart home still runs at the fraction of the cost compared with traditional, filament-based, lighting. Where the money is concerned, you are better off focusing on automating heating systems, saving water usage and perhaps introducing solar power to offset some of that usage. Got any comments? Let me know in this Reddit thread.