Opening Read Validation Process

When you give your opening read(s), the first thing that must happen is they are passed on for validation. This is a standard industry process. The opening reads you provide are checked against the information that the energy industry holds for your meters to make sure the reads are (roughly) inline with what they'd expect. Only once this has been completed are the reads sent on to your previous supplier.

The whole process usually takes around 2-4 weeks from the point at which you send your reads, to your previous supplier receiving them.

Gas and electricity opening reads are validated individually and by separate industry regulated companies, therefore it’s not uncommon for your previous supplier to receive these at slightly different times.

The validation process

This is carried out by an independent meter validation company. They check whether your opening read is valid or not by generating an estimated opening read of their own (based on the information the energy industry has on your meter) and then comparing the read you've provided against their estimate. If it's similar then it will pass validation, but, if it's either too high or below the last meter reading, then it'll fail. If the opening read you provided fails validation, the independent validation company will tell both suppliers to use their estimated read instead.

They generate this estimate by taking the last known read for your meter and adding an estimate of what they believe your usage may have been since your last read.

Last Read Value + Estimated Usage = Estimate Opening Read

The Estimated Usage component is calculated by taking both the time since the last read and your estimated annual consumption (EAC) into consideration. Your EAC is an industry calculated number which is managed within a centralised industry database see - How am I charged for my energy section for more information about how to find your EAC.

When the independent company compares your read against their own estimate to judge whether it is in-line or not, they do this by creating an upper and lower bound around their own estimate.

  • The lower bound is the last meter read received for that meter, this is pretty straight forward because no energy meter should ever run backwards so therefore your opening read should never be below a previous read (most reads that fail on the lower bound are because of an error made when submitting the read).
  • The upper bound is slightly more complicated. The way in which they judge whether a read is too high or not is by whether the read is more than 2.5x greater than what they think it should be.


Say for example a customer submits a read to their previous energy company on 1st October 2016 of 32,536. They switch over to us and have a supply start date of 1st December.

The validation company has decided that their estimated usage should have been 333 kWh between the 1st October and 1st December. This means that the upper bound would be 32,536 + 2.5 x 333 = 33,369 lower bound = 32,536. When we receive an opening read, if it is greater than 32,536 and below 33,369 then it will be validated. If it's outside of these then it will fail and we'll use their estimate of 32,536 + 333 = 32,869.

Once the validation process has been completed the opening read that is being used is then sent over to your previous supplier so they can use it to produce your final bill with them.

I have provided an opening read, why didn't you use it?

If the read you have given is outside the read 'bounds' it will fail validation and won't be used. That's not to say it isn't correct. The usual reason for this is that your previous supplier may not have had a recent read from you.

If you would like to use your read rather than an estimate, it is possible to dispute the estimated read used for you. Any final bill which may have already been generated will need to be changed if a new read is agreed (See My opening read is wrong for more details).

If the opening read provided is too high

Following on from the example above, if we received an opening read of 34,000 it would fail validation because its greater than the upper bound (33,369). A read of 32,869 would then be used to open their account.

If the opening read provided is too low

If we received an opening read of 32,300 it would also fail validation because it's lower than the previous read (lower bound 32,536). A read of 32,869 would then be used to open their account.

I gave my reads after the opening read window

If we haven’t received an opening read from you by 5 days after the date you have come on supply we'll automatically generate an estimated read for you. Unfortunately even if you give us these reads on the 6th day, the estimated read may have already been generated and sent off to your previous supplier to close your account with them.

That's not to say that we can't use the read that you have given us but there is a chance that you will have received a final bill based on an estimate rather than your read. If this has happened and you want to start your account on your own read we will follow the Disputed Read process (See - My opening read is wrong for more information) and we will try to get the change over read agreed with your previous supplier. You may also get a revised final bill from your previous supplier using your actual read rather than an estimate.

I didn't provide an opening read

If we haven’t received an opening read from you, we'll use the estimated opening read to start your account off with us and send the opening estimate over to your previous supplier so they can close your account with them at the same point.

If you have recently given your previous supplier a read, then the estimated read should be fairly accurate, so you shouldn't worry too much. It is still worth double checking that the opening estimate is roughly in line what your meter is displaying. If your previous supplier hasn't had a recent reading then there's a chance that this read isn’t quite right and we'll need to get this changed. If this is the case, please get in touch with us so we can get this looked into.

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