useless at maths % saving

st999

If I used 3900 kW last year what is the % saving if I use 3400 kW this year?

bsms1147

((3900-3400)/3900)*100 =

matelodave

I'll finish the sum for you = 12.82%

System

Forgive me, but the above calculation is far too simplistic if the OP is looking for overall savings then a 12.82% saving on energy used will not translate to a 12.82% saving on the bill because of the daily (fixed) standing charge.

st999

Hengus wrote: »

Forgive me, but the above calculation is far too simplistic if the OP is looking for overall savings then a 12.82% saving on energy used will not translate to a 12.82% saving on the bill because of the daily (fixed) standing charge.

That's what I was forgetting about.


Thanks.

System

I am with OVO. A quick look at my electricity tariff comes up with £586.99 (inc VAT) for 3900kWhs of electricity and £525.20 for 3400kWhs. This equates to a saving of £61.79 or 10.53%.

matelodave

Yes, but's not what he asked

Belenus

st999 wrote: »

If I used 3900 kW last year what is the % saving if I use 3400 kW this year?

If you post an image of your bill, with personal details blanked out, showing your standing charges, usage charges etc, your saving can be calculated.

Without knowing your fixed charges and any variation in unit charges based on consumption etc, it is not possible to give an accurate saving figure.

Alternatively, if your meter was read for each bill, add up all your bills for this year, add them up for last year and work out the percentage difference. That won't work if you had estimated readings that were different to actual readings.

Why do you want know?

Nada666

matelodave wrote: »

Yes, but's not what he asked

Actually, in context, that is what he asked.

Maths questions includes real world complications and considerations and assumptions. He did not ask you to work out an abstract numerical percentage calculation.

True, there is ambiguity - it is possible his only concern what a percentage change in usage rather than cost.

Anyway, if he is spending £4.8 MILLION* pounds per year then give or take a £95 standing charge is insignificant.

* (That is, if, as he wrote, he used a continuous load of 3,900 kW 24 hours per day for a year (rather than 3,900 kWH) )

tronator

matelodave wrote: »

Yes, but's not what he asked

Nada666 wrote: »

Actually, in context, that is what he asked.

What context? The OP asked the simple question how much energy he saved.

If he wanted something else calculated, then he should have said so and include the price per kWh and the daily standing charge.