Click picture for a two-year-old story about Smart fridges in the UK. But who's smarter? The fridge, or the cat?


While washing up after my last Clever House instalment I started thinking or all the things I might also want my clever house to do. Okay – so the list did start with ‘washing up’, but I know you can already get machines that can do that for you. So should I get one?

You can also get Smart fridges – it was after seeing one of these, and feeling inadequate that my fridge didn’t have a ‘party mode’, that I thought how a clever house could operate in a similar way (Party mode, Eco mode, Max Profit mode).

The Smart fridges that are currently being trialled can do a little of what I would like my clever home to do. They look at the Hz rate on the mains (you know – mains electricity in the UK alternates between positive and negative 50 times a second, so is said to be at 50Hz).

Now, it happens that, when there is slightly more demand than supply in the national grid, the extra strain slows the power station generators down slightly. This means that sometimes electricity comes to our houses at slightly less than 50Hz, maybe 49.8 Hz. There might also be times when there is a little too much power in the grid, and the generators start to spin up to the heady heights of 50.2Hz or so. (Look for yourself) 

Vary the Hz rate too much and things start to break – so the Hz rate for the national grid is constrained within legally binding limits. To guarantee this, at any one time a number of power stations are run at part throttle against Hz rate. This means should the rate drop a little, a steam valve in the power station instantly opens a little and more power is released onto the grid.

The problem with running power stations at part throttle is that – like any machine – they are at their most efficient at full throttle, so the part-throttle running has a carbon penalty. It’s hard to work out what this is, but the figure the industry seems to have settled on is around 2.2 million tonnes of CO2 a year. If you imagine that a single average house is responsible for about five tonnes of CO2  a year, this is the equivalent of 440 thousand houses.  Wow!

Here we come back to Smart fridges. Because the idea with the Smart fridges is that, instead of running all the nation’s power stations against Hz rate, we run the fridges against it.

The fridges in the trial constantly monitor the Hz rate (which is the same at any point on the national grid, including at the fridge’s plug). If it dips down, and the fridge is cold enough and on, it will switch off. Likewise if the Hz rate goes up, and the fridge is not too cold already and off, the fridge will turn on. Simple! Well it is slightly more complicated than that, but you get the idea.

So if we all had these fridges, we wouldn’t notice any difference to the temperature of our beer, but we could save the nation 440,000 household’s-worth of carbon.

So back to washing up – urh…

… But couldn’t a dishwasher do the same as a smart fridge? In fact, couldn’t a smart dishwasher do even more than that – not just working against Hz rate (though it could do that as well of course) – could it work against a variable tariff?

Well, there is no reason why your new-generation domestic appliance should not be able to communicate with your clever house’s brain to ask whether it should come on now, or communicate back to the clever house that you have put it on ‘Party Mode’ and it doesn’t care what the tariff is because it’s got to get the washing up done ‘right here – right now’.

Which reminds me… think party mode and finish the washing up!

But how can doing the washing up be party mode, I hear you ask? It’s because, during a party, your clever appliance assumes you’ll be needing to use it  more – washing up the worst of the dishes, or opening the fridge door a lot to get beer out, for example. The Smart fridge’s party mode cools the fridge down to its minimum temperature to compensate for the heat lost with  door-opening. (Conversely, Eco mode keeps the fridge just below its maximum safe temperature.)

Next: clever heat storage.