Save up to 33% on the cost of electricity

[Deleted User]

One thing we can all do easily to save up to 33% on the cost of electricity is to use your heavy consumption appliances such as the oven, vacuum cleaner, toaster, microwave, washing machine and dishwasher etc at the same time you would normally use gas central heating rather than when you are not heating the house.

Assuming 15p for gas, 50p for single rate elec and using gas central heating with 90% efficiency (therefore 17p/kWh output) and thermostatic controls are in use.

• 100% of the energy that your electric appliances use is converted to heat. Usually, all of that is released into your home - exceptions are things like vented tumble driers that release some of the heat outdoors and the heated water that goes down the drain from a dishwasher/washing machine. But an electric oven is a great example of 100% retention in the house.
  
  
• So if your electric appliance uses 1kWh of electricity then your home gains 1kWh of heat
  
  
• Therefore, your central heating will need to produce 1kWh less heat energy to reach the same temperature set by the thermostat.
  
  
• Your gas central heating will cost 17p per kWh so the 1kWh heat from the electric appliance will offset this and you will save 17p but spend 50p on the electricity - a net cost of 33p for that 1 kWh of heat.
  
  
• Let's say your gas CH output is 30kWh of energy to heat your house on a particularly cold day so the cost is £5.10. Let's say you now use 3kWh of electricity whilst your heating is on, cost is £1.50 but you will now only use 27 kWh of gas and therefore £4.60 of gas + £1.50 of elec = £6.10
  
  
• So it has only cost you £1 extra compared to running those appliances when the heating is off which would cost £1.50 because the heat is wasted because you didn't want to use it - 50p difference.
  
  
• 50p / £1.50 = 33% saving
  
  
• If you use electric heating then the savings could be even higher, depending on if you are using night rate elec or day rate etc.
  
  
• If you use gas for cooking - your savings will be even higher, essentially "free" to use your gas hob/oven when the heating is already on.

But, the electrical heat must be released into the house in such a way that it influences either the main thermostat or thermostatic valves on the radiators in the room the electrical energy is used, little benefit from doing the above in an unheated utility room for example, other than a slight reduction in heat transfer from the rest of the house. 

Also, some electric appliance heat is released slowly, eg oven/dishwasher feels warm for about half an hour after use so make sure that half hour is within the heating on period.

Although I used high consumption appliances in the example, it applies to nearly all electrical appliances such as TV's, computers, lights, etc, as said, the only exception is where some of the heat is released outdoors / down the drain.

In fairness a lot of people will probably use things like the oven in the evening when the heating is on anyway already, but useful for people who might put their dishwasher on an overnight timer or leave a slow cooker on during unheated hours. Also gives awareness that once your heating period is over, minimise all other electrical use. Even delaying your cup of tea/coffee until your heating comes on will result in that 33% saving from your kettle, vacuum cleaning when the heating is on etc.

pochase

15p gas against 52p electricity is 29% and not 33%.

You list 

heavy consumption appliances such as the oven, vacuum cleaner, washing machine and dishwasher

to say later it does not work for washing machine and dishwasher?

A vacuum cleaner uses 0.8KWh for per hour of which only a part will generate heat.

Mstty

pochase said:

15p gas against 52p electricity is 29% and not 33%.

He did qualify that although maybe not as accurately as some may like to 51.8p and 14.8p as an average. (Close enough and I like his enthusiasm)

Assuming 15p for gas, 50p for single rate elec and using gas central heating with 90% efficiency (therefore 17p/kWh output) and thermostatic controls are in use.

[Deleted User]

Yes, just rounded the figures for ease but if you want to do it at 14.8p and 51.8p then 31.7% is the correct figure - big assumption though is the 90% gas boiler efficiency, not sure how accurate that is but doubt it is higher.

Mstty

Because I have separate thermostats for every room should I move the kettle to the room not up to the set temperature for maximum efficiency?

I may get some strange looks from the Mrs when I take the microwave to the downstairs toilet because the temps already met in the kitchen to heat up my leftover curry🤣🤣

pochase

Only your heading is wrong, you save exactly 0% on the electricity cost.

What you mean is that some of the electricity you use generates heat, that does not need to be generated by gas. 

So for 1KWh generated heat from electricity you need less gas, which will save gas cost, but not electricity cost.

Cardew

pochase said:

15p gas against 52p electricity is 29% and not 33%.

You list 

heavy consumption appliances such as the oven, vacuum cleaner, washing machine and dishwasher

to say later it does not work for washing machine and dishwasher?

A vacuum cleaner uses 0.8KWh for per hour of which only a part will generate heat.

If 0.8kWh is used by the vacuum cleaner it will ALL generate heat. (0.8KWh for per hour is incorrect)

The washing Machine and Dishwasher also convert all of the energy used into heat. However as the OP stated some of that heat will be wasted as the hot water it produces goes down the drain.

If you used the vacuum outside in the garden that heat would be wasted!!

Petriix

That's some pretty imaginative mental gymnastics. Yes, electricity consumption generates heat. But you'd save much more money by simply reducing your use of those high powered appliances and turning your heating down. 

The principle of avoiding wasting heat is sound, but you should really focus on targeting the heat you do generate being derived from the lowest cost sources.

It's an entirely reasonable suggestion to camp out in one room with the kettle and microwave so that you retain the heat in that room and reduce the need for heat. However, it's objectively cheaper to simply drink less tea. 

QrizB

Cardew said:

If you used the vacuum outside in the garden that heat would be wasted!!

Thanks, you've reminded me that my car needs a clean

GingerTim

QrizB said:

Cardew said:

If you used the vacuum outside in the garden that heat would be wasted!!

Thanks, you've reminded me that my car needs a clean

Bring your car into the house when you do to make sure you don't waste any heat!

FreeBear

Cardew said:

pochase said:

15p gas against 52p electricity is 29% and not 33%.

You list 

heavy consumption appliances such as the oven, vacuum cleaner, washing machine and dishwasher

to say later it does not work for washing machine and dishwasher?

A vacuum cleaner uses 0.8KWh for per hour of which only a part will generate heat.

If 0.8kWh is used by the vacuum cleaner it will ALL generate heat. (0.8KWh for per hour is incorrect)

The washing Machine and Dishwasher also convert all of the energy used into heat. However as the OP stated some of that heat will be wasted as the hot water it produces goes down the drain.

Um, nope.

An electric motor (as found in a vacuum cleaner or washing machine) converts electricity in to mechanical movement. Any heat generated by the motor is caused by losses within. If all the energy were to be converted to heat, the motor wouldn't spin. So no suck (for a vacuum cleaner) and no spin (for a washing machine).

Duffer's guide - https://en.wikipedia.org/wiki/Electric_motor