Some of us with old, ineffective night storage heaters may have decided that, the price of electricity being what it is, there are better ways of keeping warm. If the heaters aren't being used, or used as much as they once were, it may be that the higher unit rate for peak-time usage means that an Economy 7 tariff may be more expensive overall than a single-rate plan. This post may help you decide.
You will need to know how your current electricity consumption is split between peak and offpeak periods. The last six months usage should give a fairly good indication, so now in February:
- Find your bill for last August, or look it up online. Make a note of the peak and offpeak meter readings for the beginning of the period, e.g. 1 August.
- Find the same figures on your bill for last month (January), this time taking the readings for the end of the period.
- Subtract the peak reading for August from the one for January to find the peak-time consumption for the whole period. Similarly, subtract the offpeak reading for August from that for January to find the offpeak consumption.
- Add these two figures together to get the total consumption for the period.
- Divide the offpeak figure by the total to find the proportion of consumption attributable to offpeak usage. This should be a number between, say, 0.10 and 0.90, but will in most cases be closer to 0.30. We'll call it P.
Now find the two tariffs you want to compare. Visit Our plans & prices to see all those available for your location, meter type (multi-rate) and payment method. You should see some Economy 7 plans where one is the one you're already on, and another under the same heading (e.g. Simpler Energy - 01/01/2024) where the Unit rate (peak) and Night unit rate (offpeak) are the same. Make a note of the three rates. We'll call them a, b and c, where a and b are the different peak and offpeak rates while c is the single rate. We'll ignore the difference in standing charges for now, because it's probably immaterial.
Back to your calculator: work out (a-c)/(a-b). The result should be somewhere between 0.30 and 0.45. We'll call this number Q.
If P is less than Q, Economy 7 isn't right for you. If P is bigger than Q, Economy 7 is saving you money.
If P is only slightly less than Q, you might be able to save by shifting more consumption to the offpeak period. This could be running power-hungry appliances like tumble dryers, dishwashers and washing machines overnight. You could use cheap clockwork time switches (e.g. these ones at £15 for 3) to start them half an hour after the offpeak rate kicks in, or if you know how long they run for, to make sure they're finished before peak rate starts.
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An example from my own figures:
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| Readings: 1 August        Peak        6977  Peak usage 7492 - 6977 = 515  Rates: a = Unit rate                27.46  I'm right on the limit, so it makes little difference in my case. This means, though, that I should keep a careful eye on the next price change (due 31 March) and do the comparison again. If it's changed in my favour, well and good. If it's gone the other way, I should consider asking for my plan to be changed to single rate. |
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UPDATE 26/04/2024: This NB is apparently no longer true:
[NB Sadly, if anyone has done this (changed from Economy 7 to single rate), it's irreversible. The only way to go back to Economy 7 currently is to have a new meter installed, and if that's possible, it may not be free.]
See this post:
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[If anything isn't clear, please reply to explain what.]
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