Here in the UK smart meters have been available from the big six power utility providers for some years. I’ve refused the free installation service as the first generation smart meters could not be ported if you changed providers. This changed with the rollout of the 2nd generation meters and so we’ve now had the system installed for gas and electricity consumption monitoring.

What’s consuming 300 watts?

Several years ago I bought a cheap electric power monitor from Maplin, another casualty of the high-street, that indicated the house standby power was around 300w. That’s 300w of essentially wasted electricity. The Maplin device sends a new reading every 30 seconds and the monitor has a similar latency so it can take a minute or two to see the difference between unplugging one item and another. So it’s time consuming looking for differences to identify where the power is going.

I hooked up the monitor to a Raspberry pi and wrote a little Python program to log the power in the hope of processing the data at some point. Of course, I never got around to it and ended up puzzled as to where the 300w was going.

Click on a few years with the new smart meter installed it confirmed our power consumption with everything switched ‘off’ is still around 280 watts. So what is consuming this phantom power – is it the smart meter?

After switching off each circuit at the fuse box I found the culprits are on the house ring (95w), garage (140w) and upstairs lighting circuits (31w). The kitchen ring has around 13w standby probably due to a number of remote control sockets and the power meter’s supply!

It’s surprising how all this standby power adds up and how tech is mostly to blame. The ring has the BT broadband hub which drinks about 15w and arguably is actually doing something rather than just idle.

There are also six 1Gb/s ethernet switches that take about 60w plus a wifi and smart lighting hub another 15w with the remainder remote control sockets. The ethernet is used for TV streaming of Netflix, Prime and BBC iPlayer – wifi can’t support the bandwidth reliably – but the 1GB switches remain on continuously when not being used, 60w day and night.

An old poorly chosen fridge in the garage is the likely 140w guzzler plus the outdoor motion sensor lighting that’s permanently on standby drinking a few watts each.

Nag nag nag

One of the benefits of having a smart meter continuously displaying your home’s power consumption is the visibility it brings. 3.3Kw making a cup of tea, 1.6Kw defrosting some bread in the microwave, 1.2Kw as the underfloor heating comes on in the den. 2.65 Kw when the dishwasher kicks in. These power spikes from the quiescent become familiar and awareness of the cost of running home appliances makes you think.

Smart meter 2.68KW Weekly Budget Exceeded

You can choose various combinations of dashboard information on the smart meter. A combined view shows the total cost per day of gas and electricity with traffic light colours for low medium and high consumption.

Or you can focus on just electricity or just gas. Gas is not a concern as off means off. Our old Potterton gas boiler, that will soon be replaced, does not have a wasteful pilot light that is always on waiting for action.

It’s the electricity that’s tricky. Perhaps I should not complain. Replacing the old tungsten lighting with compact florescent and now LED has made a huge difference over the years. Our kitchen originally used five 60w reflector bulbs along with six 20w halogens for under cabinet lighting which consumed 420 watts. That reduced to around 160w with LED with over twice the lux.

UK Standby Power Costs £4bn?

After a few months of watching  the nagging smart meter and consciously switching off devices that we don’t use much to avoid the standby consumption the lowest reading showed 180w. It does not sound much but that’s around 60p per day or £220 per year. With 27.6m households in the UK assuming let’s say 150w standby power on average (a wild guess given we have a few more tech gadgets than most) and that’s costing the UK over £4bn in wasted power consumption. Yes 4 billion pounds and quite a lot of CO2.

Update January 2026

As it’s been over 5 years since writing this post a recent comment has prompted me to bring the story up to date. With today’s energy prices,  we’re now paying 26p/kWh and 47p/day standing charge for electricity.

Solar

Our energy costs, like many other households in the UK, have doubled since 2019. In late 2022 we installed a 4.2KW solar PV system using SolarEdge inverter and optimisers. Our south facing roof appeared an idea site for the 11 panels, generating an average of 3.5MWh / year. But we needed power optimisers due to tree shading which has a significant effect in winter months.

During the energy price hikes we’ve taken advantage of low cost electricity with self consumption. Battery storage offered too little ROI back in 2022 and although battery costs have fallen, payback for us exceeds the estimated 10 year battery life. So while there’s no compelling reason for us to install solar battery storage, those homes with PV that cannot self manage consumption may find a better use case.

Monthly PV generation kWh

With 3 years of solar data to hand I’ve found on average we’re consuming around 2.3MWh a year and exporting around 2.0MWh. So we have to pay 26p for around 300kWh a year – that’s £78. Without solar it would cost us £600. We get 15p / kWh on an export tariff, generating £300. So solar is saving us over £800/year and should pay for itself in 5 years if current energy prices remain.

Octopus Energy Smart Tariffs

One reason why battery technology offers so little gain for us is the Octopus Outgoing tariff. It pays us 15p/kWh for any surplus we generate so is in effect an Octopus battery. Although we can manage self consumption — running dishwasher and washing machines during sunny days when we generate most electricity — we just watch the smart meter showing Export power and think about it charging up the virtual battery.

IHD Solar Export

Octopus Energy, now the largest UK supplier, have put some effort into smart tariffs. We tried their Tracker tariff that tracks wholesale energy prices on a daily basis. Over a year it worked out about 15% cheaper but cost could and did spike with geopolitical events.

Standby Power

After a 2022 power audit I replaced the Zyxel network switches with TP-Link and reduced total load by 25w. Tapo remote control power monitoring sockets replaced the RF remote control sockets to save another 12 watts. Tapo’s P110 sockets allow real-time power monitoring which helps identify hungry, inefficient devices. We could switch these off over night to further reduce phantom load.

Of course all the new tech cost money. But each Zyxel switch cost around £11 year to run so they would pay for themselves in a couple of years. Waiting for Amazon Prime day special offers also helped kit updates to minimise cost. And selling the old kit on a eBay avoided e waste and reduced upgrade costs.

However, our night time consumption has risen to around 160w/h compared to 124w in 2019. This may seem strange given all the attention we’ve paid to lowering standby use. I think most of the extra watts are down to increased refrigeration following the kitchen refurb along with new underfloor heating pumps and control. While we splashed out on an efficient Liebherr fridge and separate freezer, the increased capacity consumes more power to run. It has meant we no longer need the smaller fridge in the garage but overall it’s a tad more to run.

Lessons learned

It requires discipline to switch off stuff – that’s why many people don’t bother. They just hit the standby button on the remote and pay for the convenience.

Inductive loads

Inductive loads, such as transformer powered vintage tech and electric motors are hungry. Power companies don’t like inductive loads so you pay for the privilege with the much misunderstood power factor. Smart meters often show power factors, hidden within the push button menu, and checking can help lower your running costs.

As you may see from posts here on Radio Retro, I like vintage technology and use it daily. This does come at a premium. Transformer based, our Beomaster 9000 draws nearly 30 watts on standby. If left plugged in that consumes nearly 3/4 kWh per day which sure adds up over the year! I’ve solved the problem by using a Tapo socket and switching it on only when we need it.

Don’t leave your technology plugged in on standby – switch it off when not in use! Especially vintage tech that uses a transformer power supply

Air Fryers

Although our air fryer has been far from trouble free – see Instant Pot Vortex Plus Close Basket Fault – running an air fryer is a great way to save money over a conventional electric oven. The air fryer costs around 70% less to run than our built-in Neff ovens. In fact our Neff combination microwave – see Neff Built-in Microwave Oven Faults – has not been used for a couple of years and is purely there for show!

Think twice before spending large sums on built in kitchen appliances!

Security

Security costs also mount up. Older CCTV systems which rely on a spinning hard drive and IR lighting can consume 40 watts during the nighttime hours.  Newer systems and cameras offer SSD or SD card storage which lowers power running costs. But watch out for cloud based set ups that require subscription services. So go ahead and replace the hard drive with an SSD where you can.

Hope this helps – leave a comment if you have similar data to share.