Smart control is all you need, this could be a smart plug, BMS that control heating and/or hot water can be asked to help.

I would be happy for my fridge and/or freezer to switched off for a few hours, even four hours by my supplier by means of a smart plug.

I don’t presently charge my electric car during peak periods but see no reason why that facility was removed or blocked and re energised late evening.

None of the above is available via my energy supplier

I don't see the need for any active 'demand-side management' for the stated applications of dishwasher, washing machine and immersion. Washing machines tend to have timers built in, so we typically run ours in the early morning. Immersions [should] all have timers too so again, just run them overnight. Our dishwasher doesn't have a timer but we don't use it that often, but I'd say that simply running it outside the evening peak period would gain most benefits, or perhaps start it as you go to bed.

I wouldn't be happy to see our fridge-freezer disconnected for anything other than a short time at the times that matter. The freezer will only keep things frozen if it isn't opened, and we often need to open it during peak hours. Overnight and at other unused periods it should be minimising its own consumption anyway, so I doubt there's much benefit from cutting its power.

Your existing setup sounds good, so the improvements you make might not save enough to pay for any fancy kit.

Haven't had chance to try it but this looks promising
https://shop.pimoroni.com/products/pi-mote-control-starter-kit-with-2-sockets?variant=1066571265¤cy=GBP

Freezer: having grown up somewhere with regular power cuts, IME a freezer doesn't defrost within a few hours of no power and neither does the stuff in the fridge spoil. So a simple timeswitch on the plug should do the job to knock it off during evening peak. However the hourly power consumption of a domestic fridge or freezer isn't actually very much, so might not be worthwhile delaying it, it's more relevant for industrial scale.

When I looked at UK variable electricity tariffs there was no way it was going to be worth it unless your heating and water were electric.

there are some very cheap wifi plugs around - the Sonoff wifi plugs are well made and you can pick them up for as little as £8 each. Bare wire relay switches (rather than plug/socket) are even cheaper. Their standby power consumption was impressively low when I measured it and you can set schedules using their own smartphone app (or use Nest/Google Home/Alexa type things).

Unusual for dishwashers and washing machines not to have built in delay start though.

Surely not worth switching off fridge/freezer - it's not a constant load, only cuts in when required and if it's not being opened will run fairly infrequently. I really don't want my fridge letting stuff warm up if I am using it.

When I looked at this there really wasn't much at all that was ever going to pay back the upfront outlay. Standby consumption of any modern appliance is low now. Most impactful stuff is probably wifi/modems, computers, printers, TV set top box (our sky box is fairly high consumptions but needs to be if it's going to work as a recorder)

Posted By: tonyreducing peak demand nationally is a problem that this could help with

+1

also your earlier comment about hundreds of thousands doing it...

Of course, such savings will happen IN ANY CASE, once smart meters become compulsory like in France...

then the savings will go *a small way* to alleviating the massive additional load of the data centers & other infrastructure necessitated by the smart-meter network in the first place...namely around 0.44 terawatthours per year, equal to the usage of a city of 250,000 inhabitants...

"what you loses on the rounbdabouts, you loses also on the swings"

gg

We are all rather niche on here - most people I know would think nothing of putting a discretionary load on in the evening peak.

Once we get to electric car charging if there isn't an incentive the first thing many people will do when they get home is put their electric car on a fast charge.

Out of curiosity, I unplugged our freezer over the evening peak period, and measured the temperature inside.

Before I unplugged it, the stuff inside was at -20 degC and it had 'warmed' up to -14degC after being turned off for 4.5 hours. Nothing had defrosted at all and I'm totally happy with the food safety.

It's a fairly average under-the-counter freezer about 5 years old.

When I plugged it back in, the motor ran continuously for at while, as it chilled back down again. Presumably using about the same electricity as it would normally have done over 4.5hrs.

From carbonintensity.org.uk, the grid was around 310gCO2/kWh during the evening peak, and had fallen to 295gCO2/kWh by the time I put it back on.

The freezer uses about 0.5kWh each day which is 20W on average.

So the experiment deferred 20W X 4.5h = 0.09kWh of consumption from 310 to 295g/kWh. So saved (310-295)*0.09 = 1.4g of CO2

Multiplying our average consumption (10kWh/d) by yesterday's average intensity (285) suggests we accounted for about 3000g of CO2 yesterday from electric (maybe more as I don't have per-hour electric readings yet, and accepted that the marginal intensity is more than the average intensity)

So the freezer experiment reduced our CO2 by 1.4/3000 = 0.05%

We have a flat rate tariff so saved no money.


Now every little helps, but as expected the CO2 saving from this experiment made negligible difference. Not enough to be worthwhile doing it again, or to be worth buying an intelligent freezer or a plug gizmo that could do it automatically.

Absolutely!

During that peak period on Thursday the grid delivered 45000MW, so the nation's freezers (say 26m households @ 20W) accounted for 20*26/45000 = about 1% of load - so not really enough to change the grid stability game if they were all switched off.

If say half the UK households were using immersions to heat say 200l of water every day, 200l * 40deg * 4200J/kgC / 24 /3600 = 400W daily average per household. The nation's immersions would come to 26/2*400 = 5200MW, so more than 10% of peak grid flow and worth interrupting... that's maybe where to focus your efforts JMS?

But if there had been 5 million car chargers @ 5kW that would be 5*5000 = 25000MW which is an extra 55% more on top of the 45000MW that was delivered on Thursday. Can't see how that much extra load could be added to the existing grid without demand time management.

>> simply require that all tariffs include a somewhat higher price for electricity during the evening spike?

Yes, good plan, and I think that implementing that would require everyone to have a smart meter (sorry, Gyrogear!). I don't think most people have a time switch on their immersion (just my observation, not seen any figures) so we'll all require to fit one of those as well.

Actually the first wave of smart meter tariffs with hour-by-hour pricing, might be the start of a solution. If the rollout of EV charging does increase the evening peak demand, you'd also expect the price premium for evening electricity to become even more expensive than 3am electricity. That would give everyone a bigger £ incentive to run their immersions and chargers and ashps in the wee small hours.

Hopefully everyone investing in home PV storage and diverters will be able to update them to store at night time instead, the electricity price differential would make it worthwhile.

The direction of travel from CCC roadmap Treasury, dev govt is to kill off gas boilers and move more people to electric heating and hot water as well as electric mobility.

As an example, on the Octopus Agile tariff the peak (4--7pm) unit cost is typically ~25p, vs ~10p at other times.

https://www.energy-stats.uk/octopus-agile/

I would not be astonished if the unit cost of an all-day (non-ToU) tariff ended up 2--4 times that of typical units on the most dynamic ToU tariff. Not everyone will be able to move their consumption away from peak time and/or towards times when there is lots of renewable generation (and many of those people will be comparatively poor or otherwise unable to choose, so we have to be careful), but there will be significant payoff for people who can.

And that payoff will exist because flexibility will be valuable to the power system. It is already so, and that value will increase.

Rgds

Damon

Posted By: tonyI don’t think smart meters are needed

+1: say no to corporate control of private lives

gg

Posted By: tonyI don’t think smart meters are needed, all you need a controller on the car charger, internet or radio control, even a simple timer

But theres no incentive for the majority to do any of those things. Without a big hike in non ToU energy costs and the installation of the smart meters needed to avoid those charges, very little will change.

Posted By: WillInAberdeenI don't think most people have a time switch on their immersion (just my observation, not seen any figures)

Indeed. Last time I had an immersion I installed one. The issue is nearly always forgetting to turn it off.

My (Alzheimers impaired) Mother got an obsession with the immersion heater the other year and every time I visited I found it turned on despite the gas heating working perfectly. I wired a 'one hour delay' timer to ensure she could use it if necessary but couldn't leave it on.

It should be a building regs requirement to have a timer controlling Immersion heaters where fitted (in the same way as zoned heating is now required). Would add less then £20 to the system install costs.

Posted By: WillInAberdeenThat would give everyone a bigger £ incentive to run their immersions

I'm not sure. How well insulated are most domestic hot water tanks? I'm guessing if people are using their immersion at peak it's because that's when they want to use hot water. Heating the tank overnight in order to use it the following evening is unlikely to be satisfactory.

Posted By: djhBTW, the same technique should be applied more urgently to water meters. It baffles me that they're still not compulsory, but gradually increasing the price paid for unmetered supplies whilst offering free meter installation would seem to be the easiest soltion to the problem.

I seem to remember a load of newspaper scare stories when water meters were proposed but in my experience for anyone who isn't putting a sprinkler on their lawn a few times a week in summer having a meter reduces costs charges significantly.

Posted By: gyrogear+1: say no to corporate control of private lives

Why shouldn't a private company require you to have supply equipment that minimises their costs of supplying you a service (by getting readings automatically) or charging different rates at different times to encourage efficient use? Put your tinfoil hat back on and go off-grid.

I've long advocated combi or instant water heaters as greener (and cheaper) than immersion/cylinders. However I have just inherited a cylinder with the house we bought.

We use about 10kWh of hot water each day and the cylinder loses 1.5kWh each day with the insulation that it came with - 15% losses - equivalent to the tank cooling 6degC in 24h. I guess most people wouldn't notice that, if they heated water overnight for use the next day.

Most people can happily leave their immersion on 24/7, as it has an internal thermostat, it will only switch itself on when hot water is drawn from the tank and replaced by cold. So most people don't currently need a time switch.

Most hot water is drawn out to be used for washing people, in the morning or late evening, out of peak electric times, much less is used for dishes at teatime.

If the tank stats are set correctly, the immersion will only switch on if the gas hasn't heated the water sufficiently, as the immersion is usually higher up the tank than the boiler coil.

Overall I see few problems with people heating water out of peak period, but currently there's not much incentive for people to pay attention. It needs a 'Nest' type gadget that could just do it for you.


Damon, Octopus also do an hour-by-hour export tariff that pays much more for exports at 5pm than in the daytime. It looks like it would be worthwhile to buy electric at 3am into your battery and sell it back at 5pm if you hadn't used it all. That would be great for CO2. Have you looked into this? https://octopus.energy/blog/outgoing/

@WillInAberdeen: at the moment I'm sticking with Ecotricity. I'm much more interested in working out what may reduce carbon the most rather than actually playing the energy markets for income. That's why I'm also looking at this:

http://www.earth.org.uk/note-on-solar-DHW-for-16WW-UniQ-and-PV-diversion.html

and I have set my Enphase AC Battery to pretend that I have a ToU charge like Agile's:

http://www.earth.org.uk/Enphase-AC-Battery-REVIEW.html#ToU

However we manage to start to fit demand to generation rather than the other way round, we will help increase renewables and thus help tackle climate change.

Local storage (which also has the potential to to reduce grid flows and thus losses, and also reduce the need for re-inforcement) is one way of acheiving DDSM. People pooh-poohing it without looking at the numbers is quite annoying, since it can happily work alongside all the other sorts of (distributed) storage in the grids (from pumped hydro to gas linepack).

Actually I did try the load-up-at-night idea but currently on the Enphase that doesn't seem to work very well for me, as you'll see if you read down my page. Night loading *is* potentially more applicable for space heat, only needed in winter when there just isn't much local microgeneration to be had.

There also isn't much ability for me to export at 5pm when it's most needed (in winter), but minimising imports is now happening. I even have the heating forced off between 4 and 7 to minimise gas imports and the electricity to run the boiler itself during those times, ie Radbot's calls for heat are ignored and we coast on thermal storage. (Note that I'm currently *forbidden* from re-exporting since I have an export meter with FiTs.)

Rgds

Damon

PS. Note that quite a chunk of households in the UK are not on the gas grid, and use something like (very very roughly) 1/3 of all domestic electricity (Ogfem's "class 2" TDCV profile I think), some of which will be going to DHW as well as space heat. I've certainly stayed in places with immersion being the only DHW input.