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.

@cakeorwine I bought 5 spare halogen bulbs just before they stopped selling them so I could kick the driver change can a few years down the road!

I just checked and they are energy rating B so slap bang in the middle of the scale.

I meant to add the halogens are 35w so does that mean they cost 4 times as much to run as a 9w?

@Choux

I meant to add the halogens are 35w so does that mean they cost 4 times as much to run as a 9w?

Yes.

Without 'techsplaining' too much...

35 watts means that 35 joules of energy is being used every second.

So a 1000 watt device uses 1000 joules of energy every second, or 3,600,000 joules per hour.

3,600,000 joules is a unit of energy (the amount of energy a 1000 watt device uses in an hour) = 1 KWH

In the old days, we had 100 watt bulbs. However, 90% of the energy was wasted as heat energy and only 10 % went to light energy.

Luckily things have improved.

Just wondering if anyone has got their monitoring device and noticed anything interesting about their devices?

I think LED bulbs are cold to the touch? I've been round and checked all ours and found a couple of ceiling lights that burnt my finger so will replace ASAP.

I've started only putting the heating on in the morning and early evening, and I'm now running a low energy dehumidifier for half an hour morning and night in the room where I dry the washing, it's cutting the gas usage (£1.60/£2 a day instead of £4 according to the smart meter) and the house feels warmer as it is less humid, will this stop any damp issues from turning the heating down? I'm going to check the dehumidifier electricity usage.

Hello. Popping in to let you know that we're doing a Q&A with fuel poverty charity National Energy Action about these energy price hikes on Wednesday 23rd Feb at 12 noon. The thread is now open for questions here.

Thanks

Hello!

I've read through some of the pages but not all 9. I'm quite anxious about increases and it seems our electric is above average (would an electric oven be enough to explain this?) and want to reduce.

• Is it true that leaving plugs pugged in/ tv on standby /microwave clock on etc takes minimal electricity so not worth unplugging everything at night?

• How much does it cost to use my kettle. I'm aware its heating and cooling in general that are biggest electricity gobblers and I drink a lot of tea...

• Are the biggest things washing machines/ dishwashers/cooking/ showers/tumble dryers. Most of these are things we already cut down on :(

I'm not too sure why our bill is so high!

Just resurrecting this thread.

I don't know all the answers - but can offer some advice. And people can of course add their own experiences and tips

@DaisyTheUnicorn

Hello!

I've read through some of the pages but not all 9. I'm quite anxious about increases and it seems our electric is above average (would an electric oven be enough to explain this?) and want to reduce.

• Is it true that leaving plugs pugged in/ tv on standby /microwave clock on etc takes minimal electricity so not worth unplugging everything at night?

• How much does it cost to use my kettle. I'm aware its heating and cooling in general that are biggest electricity gobblers and I drink a lot of tea...

• Are the biggest things washing machines/ dishwashers/cooking/ showers/tumble dryers. Most of these are things we already cut down on :(

I'm not too sure why our bill is so high!

A kettle is about 2000 watts - so it delivers 2000 joules of energy per second. Water needs a certain amount of energy (joules) to change its temperature - and that of course varies on the temperature of water and the volume of water.

If a kettle takes 3 minutes to boil, it will use 2000 * 1/20 watt hours of energy - so about 100 watt hrs - about 0.1 units so 3p

That's a full kettle.

Standby power uses very little. I have measured our 'background' power in the house and it's about 70 watts.

Showers use a lot - an 9000 watt shower can use 150 watts in a minute - about 4.5p

Other devices - you can use a power monitor in a plug socket to see the power it uses - my washing machine uses 0.5 KWH on a 40 C cycle - about 14p

What we’ve found useful is telling the smart meter to send half hourly readings to our energy provider. We can now see a breakdown in the shell energy app of what we’ve used each day and when it’s used. It adds costs as well a week or so behind having the data available

It gives us a good idea of what is using energy. This Tuesday for electric it was microwave and oven to make jacket potatoes for lunch/cleaner hoovering in middle of day and then a wash put on and oven for tea early evening/TV and drier later around 8-9:30pm. Gas is mainly heating but there is a random late peak for OH showering before bed and an afternoon one from me boosting heating early by accident when trying to sort out the thermostat

@whatkatydid2013

It gives us a good idea of what is using energy. This Tuesday for electric it was microwave and oven to make jacket potatoes for lunch/cleaner hoovering in middle of day and then a wash put on and oven for tea early evening/TV and drier later around 8-9:30pm. Gas is mainly heating but there is a random late peak for OH showering before bed and an afternoon one from me boosting heating early by accident when trying to sort out the thermostat

DS is off school at the moment. I can see a spike at about 11.30 am when he decided to have a long shower.

This is a brilliantly helpful thread. Thank you

Enough water in a kettle for a large mug of tea is 2.5p to heat on todays rates.
My husband was berating my constant tea drinking so I worked out what it cost per drink.

I bought an energy monitor the other day, been going around the house measuring things. The Xbox is using 9w on standby, so £15 a year on my current 20p an hour rate. DH rolled his eyes, but had agreed to keep it unplugged when not in use - the DCs already unplug theirs at night, but I will be getting more strict with this.

The next calculation I need to work on is whether it costs more to dry my hair before work each day than it would to use dry shampoo and a heated straightener brush every other day instead (I can't air dry my hair as it's wavy in a not nice way and I have a bob!). I don't know how long each can of dry shampoo lasts though...

I think I've worked it out as 6p for 10 minutes hair dryer use. That's not too bad actually, I'd rather dry my hair than buy cans of dry shampoo as that's just waste and chemicals I don't need. Though I suppose I should add the cost of the water and heating that, but I don't use a lot.