Smart Home Device

AI (artificial intelligence) may be the hot topic in the technology debate, but “smart homes” technology may have a greater environmental impact.   Smart speakers, like Amazon’s Echo, can change the colour of light bulbs with just a few words.  Smart thermostats, will turn down the central heating when you go to bed.  Fridges that can tell you when you are running low on milk.  Door locks that recognise who goes in and out, and tell you via an app.  Even if you are half-way round the planet.  These are all examples of smart home devices.

The impact of Smart Home Devices usage

You would be forgiven for thinking that these devices will save you money, as well as saving the planet.  Particularly if you have read articles from the United States.  Will Smart Homes save the world? is fairly typical of the genre.  It details a list of smart technologies that in principle can reduce your energy usage.  And as a result, reduce your CO2 emissions.  How Smart Home Technology Can Reduce Your Carbon Footprint is another example from the USA.  It says:

Smart lighting stands to reduce that usage substantially. “Energy savings of up to 50% have been well documented in many [smart lighting] installations,” according to IT research firm Gartner.

How Home Automation Can Help You Go Green is another, (if advert riven) example from the USA.  The quote:

“ many homeowners choose smart lights, like the Philips Hue bulbs, to save money and make their homes more energy efficient.”

Quite positive when you compare Hue lightbulbs to incandescent lightbulbs. As America did not stop manufacturing incandescent light bulbs until 2014, the switch to energy efficient LED bulbs is well behind Europe.  In this context Hue light bulbs are much more efficient by comparison.

Another area where savings are claimed is Smart Thermostats.  In another quote from the same article:

“Instead of allowing your heating or air conditioning system to run unnecessarily, smart thermostats gauge a home’s temperature and adjust themselves accordingly to ensure there’s no energy waste. Motion sensors assist with this task, too, providing information on whether the home is currently occupied and therefore needs to be heated or cooled.”

Very true, until one looks at the advertising produced by the manufacturers.  Much of the manufacturers’ advertising focuses on fun and convenience.  This quote on the Nest Web site shows the focus is on convenience:

“Wherever you go, you’re at home.

Your mum calls to say that she’s picked up the kids from football and they’re going home. You adjust the temperature from your mobile so that they’ll be cosy.”

Sounds great, and starting up the heating in anticipation of their arrival will make the house cosier.  However, it increases the time the heating is active and thereby adds to carbon emissions.  Some systems can use geofencing and GPS to detect when you are a certain distance from home, then starts-up the boiler automatically.  This again, will add to household emissions.  Smart air conditioning has similar issues.

One idea based around smart lightbulbs is designed to warn you of rainy days.  It links a weather service to a motion sensor and smart light bulb situated close to your front door.  When you approach your door, the motion detector causes the bulb to flash red if rain is expected!  Reminding you to take an umbrella.

Certainly, smart plugs, thermostats, light bulbs and other smart devices can reduce energy use.  However, the way they are used can increase emissions rather than reduce them.

The impact of Smart Home Devices themselves

Smart devices are themselves a source of increased emissions.  Currently the most common of these devices are smart light bulbs and smart mains plugs.  Even when they are switched off, they produce emissions because they go into standby mode, which uses power.  Standby mode is required to maintain the connection with a dedicated hub or a WiFi router.  This connection is what allows the device to be controlled remotely from a smart phone, an Amazon Echo, Google Home, similar device

A typical Philips Hue LED light bulb uses 0.5 Watts in standby mode.  Its hub, which connects the bulbs to the WiFi router, uses 0.1 Watts in standby mode.  In a year, a single lightbulb uses 4.38kWh in standby mode.  The average lightbulb in a UK home is used for around two hours a day.  The annual power consumption of a normal 8 watt LED bulb (equivalent to a 60 Watt incandescent bulb), would be 5.84kWh.  The annual power consumption of a similar smart light bulb would be 10.22kWh, 43% of which would result from standby mode!  I have not added the annual 0.876kWh used in standby mode by the Hue hub, as up to 50 bulbs can function from one hub.  The power usage of the hub increases if it is running special lighting effect programs.  However, there is currently no available research on which to base the average active-usage figure.

A 2014 study by EDNA showed that most smart bulbs use a similar amount of standby power to a Philips Hue bulb.

According to an Energy Saving Trust report, there is an average of 33.6 lamps per household.  If all the lightbulbs were of the smart variety, standby mode would add 147kWh per year.  This is roughly 52kg of CO2e per household or £18.20 ex-VAT.  A hub would add a minimum 0.3kg of CO2e per household.

The impact of the Smart Home Infrastructure

In July 2017 Forbes (the American business magazine) published an article Why Smart Home Devices Are A Strong Growth Opportunity For Best Buy with the following quote.

“According to Zion Market Research, the global smart home market is likely to grow at a CAGR (compounded annual growth rate) of 14.5% between 2017 and 2022 and reach $53.45 billion by 2022.”

Smart devices are not smart in themselves.  Try asking an Amazon Echo to do something if you lose your Internet connection.  They rely on a vast network of Internet servers.  As demand grows so will the number of supporting servers.  An article from the Independent newspaper 23rd January 2016 stated that the world’s data centres consumed 416.2 terawatt hours of electricity in 2015 (416.2 billion kWh).  In 2016 the total electricity supplied in the UK was 357 terawatt hours.  In 2015 data centres accounted for around 2% of the total greenhouse gas emissions.  Air travel at that point accounted for about 2.5% of the total greenhouse gas emissions according to a study from Manchester Metropolitan University.

Research conducted in December 2017, by Netcraft a UK based Internet services provider, put the number of Web facing servers at 7,014,428.  This was a 3.2% increase on their September 2017 figure.  Growth across the whole year was over 12%.  The absolute numbers are probably an underestimate as not everyone would have responded.  However, the growth rate is probably about right.

Put another way, the average power consumption of a blade server (the type typically used in a data centre) is 320 Watts.  Over a year each server will create emissions of 1,155kg of CO2e.  However, the total amount of energy used to support each server in a data centre (the Power Usage Effectiveness, cooling and other overheads) would probably double that figure.

Certainly, not all the server growth will be attributed to Smart Home devices, but it will make a significant contribution.


Smart home devices are not inherently environmentally friendly.  The power required to operate these devices is significant.  Particularly when compared to their “dumb” alternatives.  That said, they can contribute to emissions reduction, if used properly.

First, through selective use of the technology.  As an example, rather than use a bunch of smart bulbs in room, you could use standard LED bulbs and a smart light switch.  This keeps much of the functionality (you will miss out on the joys of a multi-coloured lighting display), but reduces the number of devices consuming standby power.  Smart light switches are relatively new in the market but are becoming more available.

Secondly, making energy saving rather than convenience your priority.  The Nest Learning Thermostat can “learn” when to increase or decrease the temperature in a home.  It adjusts the temperature based on your lifestyle.  It can also use the proximity of your smart phone to turn up the heating when you walk through the door.

That said, this type of technology can be invaluable for groups, like the elderly.  My 98 years old father uses Amazon Echo voice control to turn on and off the three table lamps, fitted with Philips Hue bulbs, that light his sitting room.  As his eyesight is poor, the Echo is also his clock, his radio and his audiobook reader.  For him these things make a big improvement to his quality of life.

Smart Home technology will become widespread.  The challenge must be to utilise the benefits it offers, whilst ensuring that its potential adverse impact on energy use and carbon emissions is minimised.

Glen Winkfield