Confused about the price cap and energy consumption. Here's the thread for the physics and the maths to help you

[cakeorwine]

I've seen a lot of threads on here with people asking about their energy bills.

So a few basics here - and then I am sure people can add their own.

The price cap is an average expectation of what a household will pay. It's based on typical consumption and can vary between areas.

There is a daily standing charge and a cost per kilowatt hour.

There are figures available on typical energy consumption in a house.

According to Ofgem, the average household in the UK has 2.4 people living in it, and uses 2,900 kWh of electricity and 12,000 kWh of gas respectively. This works out as an average of 242 kWh of electricity, and 1,000 kWh of gas, per month

Electric devices have a power rating - in watts.
Devices that need a lot of power have a high power rating.

If you use a 1000 watt device for 1 hour, you have used 1 KWH of power (1000 watt hours)

That's 1 unit - about 28 pence with the new rating.

If you use the same 1000 watt device for 1/2 hour, that's 0.5 KWH - 0.5 units.

So if you use a 100 watt device for 10 hours, that's also 1 KWH (as it's low power but for a longer time)

Heaters are high users as they are on for a long time. As are immersion heaters.

Gas is different - you need to use a formula to change the volume of gas used from cubic metres into kilowatt hours.

A Smart meter will give you an indication of when there is a high energy demand, but don't forget that a low power device on for a long time will end up using a lot of energy.

So it's the kilowatt hours you need to look at whenever you question your bill.

boilj g water taps vs electric kettle vs kettle on gas hob

Specific heat capacity - my favourite!!

You need a certain amount of energy to raise the temperature of water - and that varies on the mass of water.

So let's say you have 1 litre of water = 1 kg of water

You are going to raise the temperature by say 82 degrees. From 18c to 100 c

SHC of water is 4200 J / Kg/ degree

So you need '1 4200 82 ' joules to boil it

That's 344,000 joules. A 2000 watt kettle can deliver 2000 joules per second - so it takes 344,000 / 2000 = 172 seconds to boil the kettle.

That's about 3 minutes or 1/20 of an hour. So you have used 2kw * 0.05 hrs = 0.1 units.

That's about 2.8 pence per litre of water.

Using gas to heat is cheaper in theory, but then you have to think about the efficiency of the system. How much of the gas energy is actually being used to boil the water? How much is being lost in the air as wasted energy?

Remember doing Sankey diagrams at school?

This is why maths and physics is useful

And as for boiling water taps - well, you are still having to boil the water at the start and then use it during the day.

Energy will be lost. I suppose it's a case of how much of the water you use during the day and how much of it you don't use. Imagine keeping a kettle permanently hot and just taking out what you need.

WHICH magazine has a good article. They are expensive to buy and you don't save much money

www.which.co.uk/news/2019/01/are-instant-hot-water-taps-really-cheaper-than-kettles/

I haven’t @cakeorwine but it’s clear I need to. Can’t do hourly because I’m at work not home but I can certainly do daily.

What really pees me off about the rises is the huge rise inn the standing charge for electricity.

It penalises the those all ready struggling - as usual.
No matter how careful people are with electricity, everyone will be paying over £70 per year for the privilege of having electricity on tap. I cannot understand why the standing charge has to increase so much. It means as well, that the person living in a one room bedsit with limited access to electrical items is paying the same standing charge as people in 20 room mansions.

Gas and electric standing charges were pretty similar - now the electric standing charge has almost doubled.

I think, but I don't know for sure, that the hike in standard charges for electricity absorbs the almost £70 that everyone is paying to cover the cost of the failed power companies.

Yes, that bugs me too, especially for gas, as our distributed system had a massive standing charge that was per flat, not per person. There was little incentive to cut your heating use because it made little difference to the bill, as most of it was standing charge.

I'm with E.on for electricity, and they say that their electricity is 100% renewables. I thought the reason electricity prices were also going up so much is that 1/3 of the UK electricity comes from gas - but if theirs is 100% renewable, then surely that shouldn't apply to them, and their prices should be going up as much! And I wonder what the standing charge really has to do with the fact that wholesale prices have gone up - or is it just another way for them to make profit. It's not costing them more to provide the service now, just the actual power.

The companies explain the price caps in a way that makes it seem like they have no choice but to put their prices up to that level, when presumably they do. I can understand them putting up the price of the power itself, if they have to pay more for wholesale (though do they, if it's renewable?) but the standing charge they must have some control over.

Because most "green energy" deals are just an exercise in off-setting and other bollocks.

www.theguardian.com/money/2022/jan/22/energy-bills-i-got-a-green-deal-so-why-am-i-paying-eye-watering-sums

It will be interesting when the price cap goes - to see what different deals are out there.

For low electricity users, there might be better deals than for high electricity users.

that's depressing about the Green tariffs, isn't it!

I figured something wasn't quite as it seemed, but I didn't know if it was that the companies were charging more when the didn't need to, or whether they were describing green tariffs as green when they weren't. Both kind of depressing!

there is green energy and green energy...

we chose an electricity supplier with the highest renewable without off-setting.
tbh that's sometimes not easy to find out. imo greenwashing should be illegal.

@xXwhenwillitendXx

Suppose it's better to not have it in at all and just invest in thermals and blankets.

Also if you don’t have it on your house may become damp fairly quickly. Then that leads to health issues and expense sorting it out.

It's definitely true that there are better deals for low electricity use. I got a fix deal in Nov and mine only went from 49 to 62 dual fuel as my average electricity bill was 27 per month.

The fact of the matter is that you will be rewarded in the future for using less.

Rewarded? Not if you end up with a damp mouldy home that triggers poor health. There's no medal in the post for that.

@Nohypocrate

It's definitely true that there are better deals for low electricity use. I got a fix deal in Nov and mine only went from 49 to 62 dual fuel as my average electricity bill was 27 per month.

That's something that maybe people who use little of 1 type of fuel could look at in the future.

The maths gets complex though as you get dual fuel discounts if you go with the same company for both.

@Nohypocrate

The fact of the matter is that you will be rewarded in the future for using less.

That is irrelevant if you are unable to cover costs today

am tomorrow doesn't cut it

What I was trying to say is people who are running loads of appliances and devices constantly.
Use the washing machine, dishwasher and tumble drier daily. If you want lower bills then you have got to cut down consumption.
Also houses with 3 kids all playing x boxes for hours and on tablets and phones.

check out the manyals of your most use appliances.
washing machine & diswasher eco cycles take (a lot) longer but tend to use both less water& electricity.
buy clothes that don't need ironing.
use solar panels to charge phones/powerbanks/tablets on a sunny day

use solar panels to charge phones/powerbanks/tablets on a sunny day

Expensive to buy for the energy you get in a charge.

If you want lower bills then you have got to cut down consumption

Indeed. And society needs to find a way to make electrical items as efficient as possible so you don't use more energy than is needed to complete the task (as long as the cost of the item doesn't outweigh the energy saved)

It's no good having an incredibly energy efficient vacuum if it costs 10 times more than a regular vacuum.

CakeorWine this thread has been so helpful and interesting. Thank you for sharing your knowledge with all of us and answering questions!

Do you (or anyone) know whether it is better to leave a 5 metre strip of LEDs on, or eg 4 LED spot/downlights? I am torn because the strips have probably 100 tiny LEDs in them, versus the spotlights in the ceiling which seem brighter, but there is only one light in each (I think)?

It would be good if mini solar panels with a battery, and plugs sockets were invented cheaply for residential use, so people could charge it up during the day then run (eg) an electric heated thrown/blanket or electric heater off it.

Do you (or anyone) know whether it is better to leave a 5 metre strip of LEDs on, or eg 4 LED spot/downlights? I am torn because the strips have probably 100 tiny LEDs in them, versus the spotlights in the ceiling which seem brighter, but there is only one light in each (I think

LED lights are very low power - 6 watts for a strip - so they are not costing much to run at all.

The ceiling light I have just seen is 18 watts.

Again - that's not really a lot. If you ran it for 50 hours, it would cost 28 p.

@PearPickingPorky

It would be good if mini solar panels with a battery, and plugs sockets were invented cheaply for residential use, so people could charge it up during the day then run (eg) an electric heated thrown/blanket or electric heater off it.

I do think that society needs to move towards ways of capturing energy when it's not needed (but is being produced) and storing it for when it's needed.

During sunny days, we could capture a lot of solar energy and somehow store it for when we need energy.

Definitely an interesting future in this.